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X86: Hyper-V: APIC enlightenments

PATCH Superseded [email protected] 6 participants 28 messages Apr 25, 2018 – Apr 27, 2018

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#0 lore raw

cover X86: Hyper-V: APIC enlightenments

From: "K. Y. Srinivasan" <[email protected]>

Implement APIC related enlightenments.

K. Y. Srinivasan (5):
X86: Hyper-V: Enlighten APIC access
X86: Hyper-V: Enable IPI enlightenments
X86: Hyper-V: Enhanced IPI enlightenment
X86: Hyper-V: Consolidate code for converting cpumask to vpset
X86: Hyper-V: Consolidate the allocation of the hypercall input page

 arch/x86/hyperv/Makefile           |   2 +-
 arch/x86/hyperv/hv_apic.c          | 268 +++++++++++++++++++++++++++++++++++++
 arch/x86/hyperv/hv_init.c          |  22 ++-
 arch/x86/hyperv/mmu.c              |  78 ++---------
 arch/x86/include/asm/hyperv-tlfs.h |  12 +-
 arch/x86/include/asm/mshyperv.h    |  47 ++++++-
 6 files changed, 356 insertions(+), 73 deletions(-)
 create mode 100644 arch/x86/hyperv/hv_apic.c
Signature · 1 line
2.15.1
#1 lore raw

PATCH 1/5 X86: Hyper-V: Enlighten APIC access

From: "K. Y. Srinivasan" <[email protected]>

Hyper-V supports MSR based APIC access; implement
the enlightenment.

---
 arch/x86/hyperv/Makefile        |  2 +-
 arch/x86/hyperv/hv_apic.c       | 98 +++++++++++++++++++++++++++++++++++++++++
 arch/x86/hyperv/hv_init.c       |  5 ++-
 arch/x86/include/asm/mshyperv.h |  6 ++-
 4 files changed, 107 insertions(+), 4 deletions(-)
 create mode 100644 arch/x86/hyperv/hv_apic.c
arch/x86/hyperv/Makefile +1 -1
index 367a8203cfcf..00ce4df01a09 100644
@@ -1 +1 @@
-obj-y		:= hv_init.o mmu.o
+obj-y		:= hv_init.o mmu.o hv_apic.o
arch/x86/hyperv/hv_apic.c new file +98 -0

98 lines not on this page · raw message

arch/x86/hyperv/hv_init.c +4 -1
index cfecc2272f2d..71e50fc2b7ef 100644
@@ -242,8 +242,9 @@ static int hv_cpu_die(unsigned int cpu)
  *
  * 1. Setup the hypercall page.
  * 2. Register Hyper-V specific clocksource.
+ * 3. Setup Hyper-V specific APIC entry points.
  */
-void hyperv_init(void)
+void __init hyperv_init(void)
 {
 	u64 guest_id, required_msrs;
 	union hv_x64_msr_hypercall_contents hypercall_msr;
@@ -298,6 +299,8 @@ void hyperv_init(void)
 
 	hyper_alloc_mmu();
 
+	hv_apic_init();
+
 	/*
 	 * Register Hyper-V specific clocksource.
 	 */
arch/x86/include/asm/mshyperv.h +4 -2
index b90e79610cf7..bcced50037c1 100644
@@ -258,7 +258,7 @@ static inline int hv_cpu_number_to_vp_number(int cpu_number)
 	return hv_vp_index[cpu_number];
 }
 
-void hyperv_init(void);
+void __init hyperv_init(void);
 void hyperv_setup_mmu_ops(void);
 void hyper_alloc_mmu(void);
 void hyperv_report_panic(struct pt_regs *regs, long err);
@@ -269,14 +269,16 @@ void hyperv_reenlightenment_intr(struct pt_regs *regs);
 void set_hv_tscchange_cb(void (*cb)(void));
 void clear_hv_tscchange_cb(void);
 void hyperv_stop_tsc_emulation(void);
+void hv_apic_init(void);
 #else /* CONFIG_HYPERV */
-static inline void hyperv_init(void) {}
+static __init  inline void hyperv_init(void) {}
 static inline bool hv_is_hyperv_initialized(void) { return false; }
 static inline void hyperv_cleanup(void) {}
 static inline void hyperv_setup_mmu_ops(void) {}
 static inline void set_hv_tscchange_cb(void (*cb)(void)) {}
 static inline void clear_hv_tscchange_cb(void) {}
 static inline void hyperv_stop_tsc_emulation(void) {};
+static inline void hv_apic_init(void) {}
 static inline struct hv_vp_assist_page *hv_get_vp_assist_page(unsigned int cpu)
 {
 	return NULL;
Signature · 6 lines
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#2 lore raw

PATCH 2/5 X86: Hyper-V: Enable IPI enlightenments

From: "K. Y. Srinivasan" <[email protected]>

Hyper-V supports hypercalls to implement IPI; use them.

---
 arch/x86/hyperv/hv_apic.c          | 125 +++++++++++++++++++++++++++++++++++++
 arch/x86/hyperv/hv_init.c          |  17 +++++
 arch/x86/include/asm/hyperv-tlfs.h |   9 +++
 arch/x86/include/asm/mshyperv.h    |   1 +
 4 files changed, 152 insertions(+)
arch/x86/hyperv/hv_apic.c +125 -0
index e0a5b36208fc..7f3322ecfb01 100644
@@ -30,6 +30,14 @@
 #include <linux/slab.h>
 #include <linux/cpuhotplug.h>
 
+struct ipi_arg_non_ex {
+	u32 vector;
+	u32 reserved;
+	u64 cpu_mask;
+};
+
+static struct apic orig_apic;
+
 static u64 hv_apic_icr_read(void)
 {
 	u64 reg_val;
@@ -85,8 +93,125 @@ static void hv_apic_eoi_write(u32 reg, u32 val)
 	wrmsr(HV_X64_MSR_EOI, val, 0);
 }
 
+/*
+ * IPI implementation on Hyper-V.
+ */
+
+static int __send_ipi_mask(const struct cpumask *mask, int vector)
+{
+	int cur_cpu, vcpu;
+	struct ipi_arg_non_ex **arg;
+	struct ipi_arg_non_ex *ipi_arg;
+	int ret = 1;
+	unsigned long flags;
+
+	if (cpumask_empty(mask))
+		return 0;
+
+	if (!hv_hypercall_pg)
+		return ret;
+
+	if ((vector < HV_IPI_LOW_VECTOR) || (vector > HV_IPI_HIGH_VECTOR))
+		return ret;
+
+	local_irq_save(flags);
+	arg = (struct ipi_arg_non_ex **)this_cpu_ptr(hyperv_pcpu_input_arg);
+
+	ipi_arg = *arg;
+	if (unlikely(!ipi_arg))
+		goto ipi_mask_done;
+
+
+	ipi_arg->vector = vector;
+	ipi_arg->reserved = 0;
+	ipi_arg->cpu_mask = 0;
+
+	for_each_cpu(cur_cpu, mask) {
+		vcpu = hv_cpu_number_to_vp_number(cur_cpu);
+		if (vcpu >= 64)
+			goto ipi_mask_done;
+
+		__set_bit(vcpu, (unsigned long *)&ipi_arg->cpu_mask);
+	}
+
+	ret = hv_do_hypercall(HVCALL_SEND_IPI, ipi_arg, NULL);
+
+ipi_mask_done:
+	local_irq_restore(flags);
+	return ret;
+}
+
+static int __send_ipi_one(int cpu, int vector)
+{
+	struct cpumask mask = CPU_MASK_NONE;
+
+	cpumask_set_cpu(cpu, &mask);
+	return __send_ipi_mask(&mask, vector);
+}
+
+static void hv_send_ipi(int cpu, int vector)
+{
+	if (__send_ipi_one(cpu, vector))
+		orig_apic.send_IPI(cpu, vector);
+}
+
+static void hv_send_ipi_mask(const struct cpumask *mask, int vector)
+{
+	if (__send_ipi_mask(mask, vector))
+		orig_apic.send_IPI_mask(mask, vector);
+}
+
+static void hv_send_ipi_mask_allbutself(const struct cpumask *mask, int vector)
+{
+	unsigned int this_cpu = smp_processor_id();
+	struct cpumask new_mask;
+	const struct cpumask *local_mask;
+
+	cpumask_copy(&new_mask, mask);
+	cpumask_clear_cpu(this_cpu, &new_mask);
+	local_mask = &new_mask;
+	if (__send_ipi_mask(local_mask, vector))
+		orig_apic.send_IPI_mask_allbutself(mask, vector);
+}
+
+static void hv_send_ipi_allbutself(int vector)
+{
+	hv_send_ipi_mask_allbutself(cpu_online_mask, vector);
+}
+
+static void hv_send_ipi_all(int vector)
+{
+	if (__send_ipi_mask(cpu_online_mask, vector))
+		orig_apic.send_IPI_all(vector);
+}
+
+static void hv_send_ipi_self(int vector)
+{
+	if (__send_ipi_one(smp_processor_id(), vector))
+		orig_apic.send_IPI_self(vector);
+}
+
 void __init hv_apic_init(void)
 {
+	if (ms_hyperv.hints & HV_X64_CLUSTER_IPI_RECOMMENDED) {
+		if (hyperv_pcpu_input_arg == NULL)
+			goto msr_based_access;
+
+		pr_info("Hyper-V: Using IPI hypercalls\n");
+		/*
+		 * Set the IPI entry points.
+		 */
+		orig_apic = *apic;
+
+		apic->send_IPI = hv_send_ipi;
+		apic->send_IPI_mask = hv_send_ipi_mask;
+		apic->send_IPI_mask_allbutself = hv_send_ipi_mask_allbutself;
+		apic->send_IPI_allbutself = hv_send_ipi_allbutself;
+		apic->send_IPI_all = hv_send_ipi_all;
+		apic->send_IPI_self = hv_send_ipi_self;
+	}
+
+msr_based_access:
 	if (ms_hyperv.hints & HV_X64_APIC_ACCESS_RECOMMENDED) {
 		pr_info("Hyper-V: Using MSR ased APIC access\n");
 		apic_set_eoi_write(hv_apic_eoi_write);
arch/x86/hyperv/hv_init.c +17 -0
index 71e50fc2b7ef..a895662b6b4c 100644
@@ -91,12 +91,19 @@ EXPORT_SYMBOL_GPL(hv_vp_index);
 struct hv_vp_assist_page **hv_vp_assist_page;
 EXPORT_SYMBOL_GPL(hv_vp_assist_page);
 
+void  __percpu **hyperv_pcpu_input_arg;
+EXPORT_SYMBOL_GPL(hyperv_pcpu_input_arg);
+
 u32 hv_max_vp_index;
 
 static int hv_cpu_init(unsigned int cpu)
 {
 	u64 msr_vp_index;
 	struct hv_vp_assist_page **hvp = &hv_vp_assist_page[smp_processor_id()];
+	void **input_arg;
+
+	input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
+	*input_arg = page_address(alloc_page(GFP_ATOMIC));
 
 	hv_get_vp_index(msr_vp_index);
 
@@ -217,6 +224,10 @@ static int hv_cpu_die(unsigned int cpu)
 {
 	struct hv_reenlightenment_control re_ctrl;
 	unsigned int new_cpu;
+	void **input_arg;
+
+	input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
+	free_page((unsigned long)*input_arg);
 
 	if (hv_vp_assist_page && hv_vp_assist_page[cpu])
 		wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, 0);
@@ -260,6 +271,12 @@ void __init hyperv_init(void)
 	if ((ms_hyperv.features & required_msrs) != required_msrs)
 		return;
 
+	/* Allocate the per-CPU state for the hypercall input arg */
+	hyperv_pcpu_input_arg = alloc_percpu(void  *);
+
+	if (hyperv_pcpu_input_arg == NULL)
+		return;
+
 	/* Allocate percpu VP index */
 	hv_vp_index = kmalloc_array(num_possible_cpus(), sizeof(*hv_vp_index),
 				    GFP_KERNEL);
arch/x86/include/asm/hyperv-tlfs.h +9 -0
index 416cb0e0c496..646cf2ca2aaa 100644
@@ -164,6 +164,11 @@
  */
 #define HV_X64_DEPRECATING_AEOI_RECOMMENDED	(1 << 9)
 
+/*
+ * Recommend using cluster IPI hypercalls.
+ */
+#define HV_X64_CLUSTER_IPI_RECOMMENDED         (1 << 10)
+
 /* Recommend using the newer ExProcessorMasks interface */
 #define HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED	(1 << 11)
 
@@ -329,10 +334,14 @@ struct hv_tsc_emulation_status {
 #define HV_X64_MSR_HYPERCALL_PAGE_ADDRESS_MASK	\
 		(~((1ull << HV_X64_MSR_HYPERCALL_PAGE_ADDRESS_SHIFT) - 1))
 
+#define HV_IPI_LOW_VECTOR	0x10
+#define HV_IPI_HIGH_VECTOR	0xff
+
 /* Declare the various hypercall operations. */
 #define HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE	0x0002
 #define HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST	0x0003
 #define HVCALL_NOTIFY_LONG_SPIN_WAIT		0x0008
+#define HVCALL_SEND_IPI				0x000b
 #define HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX  0x0013
 #define HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX   0x0014
 #define HVCALL_POST_MESSAGE			0x005c
arch/x86/include/asm/mshyperv.h +1 -0
index bcced50037c1..f6045f3611de 100644
@@ -122,6 +122,7 @@ static inline void hv_disable_stimer0_percpu_irq(int irq) {}
 #if IS_ENABLED(CONFIG_HYPERV)
 extern struct clocksource *hyperv_cs;
 extern void *hv_hypercall_pg;
+extern void  __percpu  **hyperv_pcpu_input_arg;
 
 static inline u64 hv_do_hypercall(u64 control, void *input, void *output)
 {
Signature · 1 line
2.15.1
#3 lore raw

Re: [PATCH 2/5] X86: Hyper-V: Enable IPI enlightenments

arch/x86/hyperv/hv_apic.c static void hv_apic_eoi_write(u32 reg, u32 val) · line 105

Quoted 10 lines · On Wed, Apr 25, 2018 at 11:12:47AM -0700, [email protected] wrote:
arch/x86/hyperv/hv_apic.c +10 -0
+/*
+ * IPI implementation on Hyper-V.
+ */
+
+static int __send_ipi_mask(const struct cpumask *mask, int vector)
+{
+	int cur_cpu, vcpu;
+	struct ipi_arg_non_ex **arg;
+	struct ipi_arg_non_ex *ipi_arg;
+	int ret = 1;

Not specifically related to this patch, but hv code sometimes returns 1 on error or U64_MAX. It's slightly magical. Maybe HV_STATUS_INVALID_HYPERCALL_INPUT (3) would be more appropriate? Or we could make a new more generic error code:

#define HV_STATUS_INVALID 1

regards,
dan carpenter
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#4 lore raw

RE: [PATCH 2/5] X86: Hyper-V: Enable IPI enlightenments

Quoted 31 lines

-----Original Message-----
From: Dan Carpenter <[email protected]>
Sent: Thursday, April 26, 2018 2:32 PM
To: KY Srinivasan <[email protected]>
Cc: [email protected]; [email protected]; linux- [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; Stephen Hemminger <[email protected]>; Michael Kelley (EOSG) <[email protected]>; [email protected]
Subject: Re: [PATCH 2/5] X86: Hyper-V: Enable IPI enlightenments

arch/x86/hyperv/hv_apic.c static void hv_apic_eoi_write(u32 reg, u32 val) · line 105

Quoted 10 lines · On Wed, Apr 25, 2018 at 11:12:47AM -0700, [email protected] wrote:
arch/x86/hyperv/hv_apic.c +10 -0
+/*
+ * IPI implementation on Hyper-V.
+ */
+
+static int __send_ipi_mask(const struct cpumask *mask, int vector)
+{
+	int cur_cpu, vcpu;
+	struct ipi_arg_non_ex **arg;
+	struct ipi_arg_non_ex *ipi_arg;
+	int ret = 1;

Not specifically related to this patch, but hv code sometimes returns 1 on error or U64_MAX. It's slightly magical. Maybe HV_STATUS_INVALID_HYPERCALL_INPUT (3) would be more appropriate? Or we
could make a new more generic error code:

Quoted 1 line

#define HV_STATUS_INVALID 1

Good point. We will look at cleaning this up.

Regards,

K. Y
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#5 lore raw

Re: [PATCH 2/5] X86: Hyper-V: Enable IPI enlightenments

In reply to [email protected]

arch/x86/hyperv/hv_apic.c static void hv_apic_eoi_write(u32 reg, u32 val) · line 105

Quoted 6 lines · On Wed, 25 Apr 2018, [email protected] wrote:
arch/x86/hyperv/hv_apic.c +6 -0
+static int __send_ipi_mask(const struct cpumask *mask, int vector)
+{
+	int cur_cpu, vcpu;
+	struct ipi_arg_non_ex **arg;
+	struct ipi_arg_non_ex *ipi_arg;
+	int ret = 1;

So this indicates whether __send_ipi_mask() can send to @mask or not. So please make it a bool and let it return false when it does not work, true otherwise. If you had used -Exxxx then it would have been more obvious, but this is really a boolean decision.

Quoted 9 lines
arch/x86/hyperv/hv_apic.c +9 -0
+	unsigned long flags;
+
+	if (cpumask_empty(mask))
+		return 0;
+
+	if (!hv_hypercall_pg)
+		return ret;
+
+	if ((vector < HV_IPI_LOW_VECTOR) || (vector > HV_IPI_HIGH_VECTOR))

arch/x86/hyperv/hv_apic.c static void hv_apic_eoi_write(u32 reg, u32 val) · line 124

Quoted 10 lines
arch/x86/hyperv/hv_apic.c +10 -0
+		return ret;
+
+	local_irq_save(flags);
+	arg = (struct ipi_arg_non_ex **)this_cpu_ptr(hyperv_pcpu_input_arg);
+
+	ipi_arg = *arg;
+	if (unlikely(!ipi_arg))
+		goto ipi_mask_done;
+
+

Stray newline

arch/x86/hyperv/hv_apic.c static void hv_apic_eoi_write(u32 reg, u32 val) · line 132

Quoted 8 lines
arch/x86/hyperv/hv_apic.c +8 -0
+	ipi_arg->vector = vector;
+	ipi_arg->reserved = 0;
+	ipi_arg->cpu_mask = 0;
+
+	for_each_cpu(cur_cpu, mask) {
+		vcpu = hv_cpu_number_to_vp_number(cur_cpu);
+		if (vcpu >= 64)
+			goto ipi_mask_done;

This is completely magic and deserves a comment.

Quoted 10 lines
arch/x86/hyperv/hv_apic.c +10 -0
+
+		__set_bit(vcpu, (unsigned long *)&ipi_arg->cpu_mask);
+	}
+
+	ret = hv_do_hypercall(HVCALL_SEND_IPI, ipi_arg, NULL);
+
+ipi_mask_done:
+	local_irq_restore(flags);
+	return ret;
+}

....

arch/x86/hyperv/hv_init.c EXPORT_SYMBOL_GPL(hv_vp_index); · line 106

Quoted 8 lines

static int hv_cpu_init(unsigned int cpu)
{

arch/x86/hyperv/hv_init.c +4 -0
 	u64 msr_vp_index;
 	struct hv_vp_assist_page **hvp = &hv_vp_assist_page[smp_processor_id()];
+	void **input_arg;
+
+	input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
+	*input_arg = page_address(alloc_page(GFP_ATOMIC));

This is called from the cpu hotplug thread and there is no need for an atomic allocation. Please use GFP_KERNEL.

arch/x86/hyperv/hv_init.c static int hv_cpu_die(unsigned int cpu) · line 230

Quoted 10 lines
arch/x86/hyperv/hv_init.c +4 -0
 	hv_get_vp_index(msr_vp_index);
@@ -217,6 +224,10 @@ static int hv_cpu_die(unsigned int cpu)
 {
 	struct hv_reenlightenment_control re_ctrl;
 	unsigned int new_cpu;
+	void **input_arg;
+
+	input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
+	free_page((unsigned long)*input_arg);

Hrm. Again this is called from the CPU hotplug thread when the cou is about to go down. But you can be scheduled out after free() and before disabling the assist thing below and the pointer persist. There is no guarantee that nothing sends an IPI anymore after this point.

So you have two options here:

1) Disable interrupts, get the pointer, set the per cpu pointer to NULL, reenable interruots and free the page

2) Keep the page around and check for it in the CPU UP path and avoid the allocation when the CPU comes online again.

arch/x86/hyperv/hv_init.c void __init hyperv_init(void) · line 278

Quoted 11 lines
arch/x86/hyperv/hv_init.c +5 -0
 	if (hv_vp_assist_page && hv_vp_assist_page[cpu])
 		wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, 0);
@@ -260,6 +271,12 @@ void __init hyperv_init(void)
 	if ((ms_hyperv.features & required_msrs) != required_msrs)
 		return;
 
+	/* Allocate the per-CPU state for the hypercall input arg */
+	hyperv_pcpu_input_arg = alloc_percpu(void  *);
+
+	if (hyperv_pcpu_input_arg == NULL)
+		return;

Huch. When that allocation fails, you return and ignore the rest of the function which has been there before. Weird decision.

Thanks,

tglx
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#6 lore raw

RE: [PATCH 2/5] X86: Hyper-V: Enable IPI enlightenments

Quoted 14 lines

-----Original Message-----
From: Thomas Gleixner <[email protected]>
Sent: Thursday, April 26, 2018 3:09 PM
To: KY Srinivasan <[email protected]>
Cc: [email protected]; [email protected]; linux- [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; Stephen Hemminger <[email protected]>; Michael Kelley (EOSG) <[email protected]>; [email protected]
Subject: Re: [PATCH 2/5] X86: Hyper-V: Enable IPI enlightenments

On Wed, 25 Apr 2018, [email protected] wrote:

Quoted 12 lines

arch/x86/hyperv/hv_apic.c static void hv_apic_eoi_write(u32 reg, u32 val) · line 105

Quoted 6 lines
arch/x86/hyperv/hv_apic.c +6 -0
+static int __send_ipi_mask(const struct cpumask *mask, int vector)
+{
+	int cur_cpu, vcpu;
+	struct ipi_arg_non_ex **arg;
+	struct ipi_arg_non_ex *ipi_arg;
+	int ret = 1;

So this indicates whether __send_ipi_mask() can send to @mask or not. So please make it a bool and let it return false when it does not work, true otherwise. If you had used -Exxxx then it would have been more obvious, but
this is really a boolean decision.

Agreed.

Quoted 78 lines

arch/x86/hyperv/hv_apic.c static void hv_apic_eoi_write(u32 reg, u32 val)

Quoted 10 lines
arch/x86/hyperv/hv_apic.c +9 -0
+	unsigned long flags;
+
+	if (cpumask_empty(mask))
+		return 0;
+
+	if (!hv_hypercall_pg)
+		return ret;
+
+	if ((vector < HV_IPI_LOW_VECTOR) || (vector >

HV_IPI_HIGH_VECTOR))

arch/x86/hyperv/hv_apic.c static void hv_apic_eoi_write(u32 reg, u32 val)

Quoted 4 lines
arch/x86/hyperv/hv_apic.c +4 -0
+		return ret;
+
+	local_irq_save(flags);
+	arg = (struct ipi_arg_non_ex

**)this_cpu_ptr(hyperv_pcpu_input_arg);

arch/x86/hyperv/hv_apic.c static void hv_apic_eoi_write(u32 reg, u32 val) · line 124

Quoted 6 lines
arch/x86/hyperv/hv_apic.c +6 -0
+
+	ipi_arg = *arg;
+	if (unlikely(!ipi_arg))
+		goto ipi_mask_done;
+
+

Stray newline

arch/x86/hyperv/hv_apic.c static void hv_apic_eoi_write(u32 reg, u32 val) · line 132

Quoted 8 lines
arch/x86/hyperv/hv_apic.c +8 -0
+	ipi_arg->vector = vector;
+	ipi_arg->reserved = 0;
+	ipi_arg->cpu_mask = 0;
+
+	for_each_cpu(cur_cpu, mask) {
+		vcpu = hv_cpu_number_to_vp_number(cur_cpu);
+		if (vcpu >= 64)
+			goto ipi_mask_done;

This is completely magic and deserves a comment.

Quoted 10 lines
arch/x86/hyperv/hv_apic.c +10 -0
+
+		__set_bit(vcpu, (unsigned long *)&ipi_arg->cpu_mask);
+	}
+
+	ret = hv_do_hypercall(HVCALL_SEND_IPI, ipi_arg, NULL);
+
+ipi_mask_done:
+	local_irq_restore(flags);
+	return ret;
+}

....

Review

Quoted 4 lines

static int hv_cpu_init(unsigned int cpu)
{

(quoted diff) +0 -0
 	u64 msr_vp_index;
 	struct hv_vp_assist_page **hvp =

&hv_vp_assist_page[smp_processor_id()];

arch/x86/hyperv/hv_init.c EXPORT_SYMBOL_GPL(hv_vp_index); · line 106

Quoted 4 lines
arch/x86/hyperv/hv_init.c +4 -0
+	void **input_arg;
+
+	input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
+	*input_arg = page_address(alloc_page(GFP_ATOMIC));

This is called from the cpu hotplug thread and there is no need for an atomic allocation. Please use GFP_KERNEL.

arch/x86/hyperv/hv_init.c static int hv_cpu_die(unsigned int cpu) · line 230

Quoted 10 lines
arch/x86/hyperv/hv_init.c +4 -0
 	hv_get_vp_index(msr_vp_index);
@@ -217,6 +224,10 @@ static int hv_cpu_die(unsigned int cpu)
 {
 	struct hv_reenlightenment_control re_ctrl;
 	unsigned int new_cpu;
+	void **input_arg;
+
+	input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
+	free_page((unsigned long)*input_arg);

Hrm. Again this is called from the CPU hotplug thread when the cou is about to go down. But you can be scheduled out after free() and before disabling the assist thing below and the pointer persist. There is no guarantee that nothing sends an IPI anymore after this point.

Quoted 4 lines

So you have two options here:

1) Disable interrupts, get the pointer, set the per cpu pointer to NULL, reenable interruots and free the page

I will implement this approach.

Quoted 10 lines

2) Keep the page around and check for it in the CPU UP path and avoid the allocation when the CPU comes online again.

Quoted 6 lines
arch/x86/hyperv/hv_init.c +0 -0
 	if (hv_vp_assist_page && hv_vp_assist_page[cpu])
 		wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, 0);
@@ -260,6 +271,12 @@ void __init hyperv_init(void)
 	if ((ms_hyperv.features & required_msrs) != required_msrs)
 		return;
 
Quoted 8 lines

arch/x86/hyperv/hv_init.c void __init hyperv_init(void) · line 278

Quoted 5 lines
arch/x86/hyperv/hv_init.c +5 -0
+	/* Allocate the per-CPU state for the hypercall input arg */
+	hyperv_pcpu_input_arg = alloc_percpu(void  *);
+
+	if (hyperv_pcpu_input_arg == NULL)
+		return;

Huch. When that allocation fails, you return and ignore the rest of the function which has been there before. Weird decision.

I should have explained this. Failure of this allocation means that we would not have the per-cpu hypercall input page which in turn would mean that we would not be able to invoke any hypercalls.

Regards,

K. Y

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devel mailing list
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#7 lore raw

RE: [PATCH 2/5] X86: Hyper-V: Enable IPI enlightenments

In reply to [email protected]
Quoted 27 lines

-----Original Message-----
From: [email protected] <[email protected]>
Sent: Wednesday, April 25, 2018 11:13 AM
To: [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; Stephen Hemminger <[email protected]>; Michael Kelley (EOSG) <[email protected]>; [email protected]
Cc: KY Srinivasan <[email protected]>
Subject: [PATCH 2/5] X86: Hyper-V: Enable IPI enlightenments

From: "K. Y. Srinivasan" <[email protected]>

Hyper-V supports hypercalls to implement IPI; use them.

---
 arch/x86/hyperv/hv_apic.c          | 125 +++++++++++++++++++++++++++++++++++++
 arch/x86/hyperv/hv_init.c          |  17 +++++
 arch/x86/include/asm/hyperv-tlfs.h |   9 +++
 arch/x86/include/asm/mshyperv.h    |   1 +
 4 files changed, 152 insertions(+)
arch/x86/hyperv/hv_apic.c +0 -0
index e0a5b36208fc..7f3322ecfb01 100644

arch/x86/hyperv/hv_apic.c line 37

Quoted 8 lines
arch/x86/hyperv/hv_apic.c +5 -0
@@ -30,6 +30,14 @@
 #include <linux/slab.h>
 #include <linux/cpuhotplug.h>
 
+struct ipi_arg_non_ex {
+	u32 vector;
+	u32 reserved;
+	u64 cpu_mask;
+};

I think we'd like to put structures like this, which are defined in the Hyper-V Top Level Functional Spec, in hyperv-tlfs.h. Also, the 5.0b version of the TLFS, which is latest, shows this structure on page 100:

	u32 vector;
	u8  targetvtl;
	u8  reserved[3];
	u64 cpu_mask;
Quoted 225 lines
arch/x86/hyperv/hv_apic.c +120 -0
+
+static struct apic orig_apic;
+
 static u64 hv_apic_icr_read(void)
 {
 	u64 reg_val;
@@ -85,8 +93,125 @@ static void hv_apic_eoi_write(u32 reg, u32 val)
 	wrmsr(HV_X64_MSR_EOI, val, 0);
 }
 
+/*
+ * IPI implementation on Hyper-V.
+ */
+
+static int __send_ipi_mask(const struct cpumask *mask, int vector)
+{
+	int cur_cpu, vcpu;
+	struct ipi_arg_non_ex **arg;
+	struct ipi_arg_non_ex *ipi_arg;
+	int ret = 1;
+	unsigned long flags;
+
+	if (cpumask_empty(mask))
+		return 0;
+
+	if (!hv_hypercall_pg)
+		return ret;
+
+	if ((vector < HV_IPI_LOW_VECTOR) || (vector > HV_IPI_HIGH_VECTOR))
+		return ret;
+
+	local_irq_save(flags);
+	arg = (struct ipi_arg_non_ex **)this_cpu_ptr(hyperv_pcpu_input_arg);
+
+	ipi_arg = *arg;
+	if (unlikely(!ipi_arg))
+		goto ipi_mask_done;
+
+
+	ipi_arg->vector = vector;
+	ipi_arg->reserved = 0;
+	ipi_arg->cpu_mask = 0;
+
+	for_each_cpu(cur_cpu, mask) {
+		vcpu = hv_cpu_number_to_vp_number(cur_cpu);
+		if (vcpu >= 64)
+			goto ipi_mask_done;
+
+		__set_bit(vcpu, (unsigned long *)&ipi_arg->cpu_mask);
+	}
+
+	ret = hv_do_hypercall(HVCALL_SEND_IPI, ipi_arg, NULL);
+
+ipi_mask_done:
+	local_irq_restore(flags);
+	return ret;
+}
+
+static int __send_ipi_one(int cpu, int vector)
+{
+	struct cpumask mask = CPU_MASK_NONE;
+
+	cpumask_set_cpu(cpu, &mask);
+	return __send_ipi_mask(&mask, vector);
+}
+
+static void hv_send_ipi(int cpu, int vector)
+{
+	if (__send_ipi_one(cpu, vector))
+		orig_apic.send_IPI(cpu, vector);
+}
+
+static void hv_send_ipi_mask(const struct cpumask *mask, int vector)
+{
+	if (__send_ipi_mask(mask, vector))
+		orig_apic.send_IPI_mask(mask, vector);
+}
+
+static void hv_send_ipi_mask_allbutself(const struct cpumask *mask, int vector)
+{
+	unsigned int this_cpu = smp_processor_id();
+	struct cpumask new_mask;
+	const struct cpumask *local_mask;
+
+	cpumask_copy(&new_mask, mask);
+	cpumask_clear_cpu(this_cpu, &new_mask);
+	local_mask = &new_mask;
+	if (__send_ipi_mask(local_mask, vector))
+		orig_apic.send_IPI_mask_allbutself(mask, vector);
+}
+
+static void hv_send_ipi_allbutself(int vector)
+{
+	hv_send_ipi_mask_allbutself(cpu_online_mask, vector);
+}
+
+static void hv_send_ipi_all(int vector)
+{
+	if (__send_ipi_mask(cpu_online_mask, vector))
+		orig_apic.send_IPI_all(vector);
+}
+
+static void hv_send_ipi_self(int vector)
+{
+	if (__send_ipi_one(smp_processor_id(), vector))
+		orig_apic.send_IPI_self(vector);
+}
+
 void __init hv_apic_init(void)
 {
+	if (ms_hyperv.hints & HV_X64_CLUSTER_IPI_RECOMMENDED) {
+		if (hyperv_pcpu_input_arg == NULL)
+			goto msr_based_access;
+
+		pr_info("Hyper-V: Using IPI hypercalls\n");
+		/*
+		 * Set the IPI entry points.
+		 */
+		orig_apic = *apic;
+
+		apic->send_IPI = hv_send_ipi;
+		apic->send_IPI_mask = hv_send_ipi_mask;
+		apic->send_IPI_mask_allbutself = hv_send_ipi_mask_allbutself;
+		apic->send_IPI_allbutself = hv_send_ipi_allbutself;
+		apic->send_IPI_all = hv_send_ipi_all;
+		apic->send_IPI_self = hv_send_ipi_self;
+	}
+
+msr_based_access:
 	if (ms_hyperv.hints & HV_X64_APIC_ACCESS_RECOMMENDED) {
 		pr_info("Hyper-V: Using MSR ased APIC access\n");
 		apic_set_eoi_write(hv_apic_eoi_write);
arch/x86/hyperv/hv_init.c +17 -0
index 71e50fc2b7ef..a895662b6b4c 100644
@@ -91,12 +91,19 @@ EXPORT_SYMBOL_GPL(hv_vp_index);
 struct hv_vp_assist_page **hv_vp_assist_page;
 EXPORT_SYMBOL_GPL(hv_vp_assist_page);
 
+void  __percpu **hyperv_pcpu_input_arg;
+EXPORT_SYMBOL_GPL(hyperv_pcpu_input_arg);
+
 u32 hv_max_vp_index;
 
 static int hv_cpu_init(unsigned int cpu)
 {
 	u64 msr_vp_index;
 	struct hv_vp_assist_page **hvp = &hv_vp_assist_page[smp_processor_id()];
+	void **input_arg;
+
+	input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
+	*input_arg = page_address(alloc_page(GFP_ATOMIC));
 
 	hv_get_vp_index(msr_vp_index);
 
@@ -217,6 +224,10 @@ static int hv_cpu_die(unsigned int cpu)
 {
 	struct hv_reenlightenment_control re_ctrl;
 	unsigned int new_cpu;
+	void **input_arg;
+
+	input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
+	free_page((unsigned long)*input_arg);
 
 	if (hv_vp_assist_page && hv_vp_assist_page[cpu])
 		wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, 0);
@@ -260,6 +271,12 @@ void __init hyperv_init(void)
 	if ((ms_hyperv.features & required_msrs) != required_msrs)
 		return;
 
+	/* Allocate the per-CPU state for the hypercall input arg */
+	hyperv_pcpu_input_arg = alloc_percpu(void  *);
+
+	if (hyperv_pcpu_input_arg == NULL)
+		return;
+
 	/* Allocate percpu VP index */
 	hv_vp_index = kmalloc_array(num_possible_cpus(), sizeof(*hv_vp_index),
 				    GFP_KERNEL);
arch/x86/include/asm/hyperv-tlfs.h +9 -0
index 416cb0e0c496..646cf2ca2aaa 100644
@@ -164,6 +164,11 @@
  */
 #define HV_X64_DEPRECATING_AEOI_RECOMMENDED	(1 << 9)
 
+/*
+ * Recommend using cluster IPI hypercalls.
+ */
+#define HV_X64_CLUSTER_IPI_RECOMMENDED         (1 << 10)
+
 /* Recommend using the newer ExProcessorMasks interface */
 #define HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED	(1 << 11)
 
@@ -329,10 +334,14 @@ struct hv_tsc_emulation_status {
 #define HV_X64_MSR_HYPERCALL_PAGE_ADDRESS_MASK	\
 		(~((1ull << HV_X64_MSR_HYPERCALL_PAGE_ADDRESS_SHIFT) - 1))
 
+#define HV_IPI_LOW_VECTOR	0x10
+#define HV_IPI_HIGH_VECTOR	0xff
+
 /* Declare the various hypercall operations. */
 #define HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE	0x0002
 #define HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST	0x0003
 #define HVCALL_NOTIFY_LONG_SPIN_WAIT		0x0008
+#define HVCALL_SEND_IPI				0x000b
 #define HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX  0x0013
 #define HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX   0x0014
 #define HVCALL_POST_MESSAGE			0x005c
arch/x86/include/asm/mshyperv.h +1 -1
index bcced50037c1..f6045f3611de 100644
@@ -122,6 +122,7 @@ static inline void hv_disable_stimer0_percpu_irq(int irq) {}
 #if IS_ENABLED(CONFIG_HYPERV)
 extern struct clocksource *hyperv_cs;
 extern void *hv_hypercall_pg;
+extern void  __percpu  **hyperv_pcpu_input_arg;
 
 static inline u64 hv_do_hypercall(u64 control, void *input, void *output)
 {
--

2.15.1

#8 lore raw

RE: [PATCH 2/5] X86: Hyper-V: Enable IPI enlightenments

Quoted 57 lines

-----Original Message-----
From: Michael Kelley (EOSG)
Sent: Thursday, April 26, 2018 3:55 PM
To: KY Srinivasan <[email protected]>; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; Stephen Hemminger <[email protected]>; [email protected]
Subject: RE: [PATCH 2/5] X86: Hyper-V: Enable IPI enlightenments

Quoted 4 lines

-----Original Message-----
From: [email protected] <[email protected]>
Sent: Wednesday, April 25, 2018 11:13 AM
To: [email protected]; [email protected]; linux-

[email protected];

Quoted 1 line

[email protected]; [email protected]; [email protected];

[email protected];

Quoted 1 line

[email protected]; [email protected]; Stephen Hemminger

<[email protected]>;

Quoted 1 line

Michael Kelley (EOSG) <[email protected]>;

[email protected]

Quoted 10 lines

Cc: KY Srinivasan <[email protected]>
Subject: [PATCH 2/5] X86: Hyper-V: Enable IPI enlightenments

From: "K. Y. Srinivasan" <[email protected]>

Hyper-V supports hypercalls to implement IPI; use them.

---
 arch/x86/hyperv/hv_apic.c          | 125

+++++++++++++++++++++++++++++++++++++

Quoted 10 lines
 arch/x86/hyperv/hv_init.c          |  17 +++++
 arch/x86/include/asm/hyperv-tlfs.h |   9 +++
 arch/x86/include/asm/mshyperv.h    |   1 +
 4 files changed, 152 insertions(+)
arch/x86/hyperv/hv_apic.c +0 -0
index e0a5b36208fc..7f3322ecfb01 100644

arch/x86/hyperv/hv_apic.c line 37

Quoted 8 lines
arch/x86/hyperv/hv_apic.c +5 -0
@@ -30,6 +30,14 @@
 #include <linux/slab.h>
 #include <linux/cpuhotplug.h>
 
+struct ipi_arg_non_ex {
+	u32 vector;
+	u32 reserved;
+	u64 cpu_mask;
+};

I think we'd like to put structures like this, which are defined in the Hyper-V Top Level Functional Spec, in hyperv-tlfs.h. Also, the 5.0b version of the TLFS, which is latest, shows this structure on page 100:

Quoted 5 lines
	u32 vector;
	u8  targetvtl;
	u8  reserved[3];
	u64 cpu_mask;

Good point. I will make the necessary adjustments.

Regards,

K. Y
_______________________________________________
devel mailing list
[email protected]
http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel

#9 lore raw

Re: [PATCH 2/5] X86: Hyper-V: Enable IPI enlightenments

In reply to [email protected]
I love your patch! Yet something to improve:

Hi Srinivasan,

I love your patch! Yet something to improve:

[auto build test ERROR on v4.17-rc2]
[also build test ERROR on next-20180426]
[cannot apply to tip/x86/core]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url: https://github.com/0day-ci/linux/commits/kys-linuxonhyperv-com/X86-Hyper-V-APIC-enlightenments/20180427-114416
config: i386-randconfig-b0-04270034 (attached as .config)
compiler: gcc-4.9 (Debian 4.9.4-2) 4.9.4 reproduce:

        # save the attached .config to linux build tree
        make ARCH=i386 

All errors (new ones prefixed by >>):

arch/x86//hyperv/hv_apic.c: In function 'hv_apic_read':
arch/x86//hyperv/hv_apic.c:73:3: error: implicit declaration of function 'native_apic_mem_read' [-Werror=implicit-function-declaration]

      return native_apic_mem_read(reg);
      ^
   arch/x86//hyperv/hv_apic.c: In function 'hv_apic_write':
   arch/x86//hyperv/hv_apic.c:87:3: error: implicit declaration of function 'native_apic_mem_write' [-Werror=implicit-function-declaration]
      native_apic_mem_write(reg, val);
      ^
   arch/x86//hyperv/hv_apic.c: In function 'hv_send_ipi':
>> arch/x86//hyperv/hv_apic.c:155:3: error: invalid use of undefined type 'struct apic'
      orig_apic.send_IPI(cpu, vector);
      ^
   arch/x86//hyperv/hv_apic.c: In function 'hv_send_ipi_mask':
   arch/x86//hyperv/hv_apic.c:161:3: error: invalid use of undefined type 'struct apic'
      orig_apic.send_IPI_mask(mask, vector);
      ^
   arch/x86//hyperv/hv_apic.c: In function 'hv_send_ipi_mask_allbutself':
   arch/x86//hyperv/hv_apic.c:174:3: error: invalid use of undefined type 'struct apic'
      orig_apic.send_IPI_mask_allbutself(mask, vector);
      ^
   arch/x86//hyperv/hv_apic.c: In function 'hv_send_ipi_all':
   arch/x86//hyperv/hv_apic.c:185:3: error: invalid use of undefined type 'struct apic'
      orig_apic.send_IPI_all(vector);
      ^
   arch/x86//hyperv/hv_apic.c: In function 'hv_send_ipi_self':
   arch/x86//hyperv/hv_apic.c:191:3: error: invalid use of undefined type 'struct apic'
      orig_apic.send_IPI_self(vector);
      ^
   arch/x86//hyperv/hv_apic.c: In function 'hv_apic_init':
   arch/x86//hyperv/hv_apic.c:204:16: error: 'apic' undeclared (first use in this function)
      orig_apic = *apic;
                   ^
   arch/x86//hyperv/hv_apic.c:204:16: note: each undeclared identifier is reported only once for each function it appears in
>> arch/x86//hyperv/hv_apic.c:204:3: error: 'orig_apic' has an incomplete type
      orig_apic = *apic;
      ^
   arch/x86//hyperv/hv_apic.c:217:3: error: implicit declaration of function 'apic_set_eoi_write' [-Werror=implicit-function-declaration]
      apic_set_eoi_write(hv_apic_eoi_write);
      ^

cc1: some warnings being treated as errors

vim +/orig_apic +204 arch/x86//hyperv/hv_apic.c

    59	
    60	static u32 hv_apic_read(u32 reg)
    61	{
    62		u32 reg_val, hi;
    63	
    64		switch (reg) {
    65		case APIC_EOI:
    66			rdmsr(HV_X64_MSR_EOI, reg_val, hi);
    67			return reg_val;
    68		case APIC_TASKPRI:
    69			rdmsr(HV_X64_MSR_TPR, reg_val, hi);
    70			return reg_val;
    71	
    72		default:
  > 73			return native_apic_mem_read(reg);
    74		}
    75	}
    76	
    77	static void hv_apic_write(u32 reg, u32 val)
    78	{
    79		switch (reg) {
    80		case APIC_EOI:
    81			wrmsr(HV_X64_MSR_EOI, val, 0);
    82			break;
    83		case APIC_TASKPRI:
    84			wrmsr(HV_X64_MSR_TPR, val, 0);
    85			break;
    86		default:
    87			native_apic_mem_write(reg, val);
    88		}
    89	}
    90	
    91	static void hv_apic_eoi_write(u32 reg, u32 val)
    92	{
    93		wrmsr(HV_X64_MSR_EOI, val, 0);
    94	}
    95	
    96	/*
    97	 * IPI implementation on Hyper-V.
    98	 */
    99	
   100	static int __send_ipi_mask(const struct cpumask *mask, int vector)
   101	{
   102		int cur_cpu, vcpu;
   103		struct ipi_arg_non_ex **arg;
   104		struct ipi_arg_non_ex *ipi_arg;
   105		int ret = 1;
   106		unsigned long flags;
   107	
   108		if (cpumask_empty(mask))
   109			return 0;
   110	
   111		if (!hv_hypercall_pg)
   112			return ret;
   113	
   114		if ((vector < HV_IPI_LOW_VECTOR) || (vector > HV_IPI_HIGH_VECTOR))
   115			return ret;
   116	
   117		local_irq_save(flags);
   118		arg = (struct ipi_arg_non_ex **)this_cpu_ptr(hyperv_pcpu_input_arg);
   119	
   120		ipi_arg = *arg;
   121		if (unlikely(!ipi_arg))
   122			goto ipi_mask_done;
   123	
   124	
   125		ipi_arg->vector = vector;
   126		ipi_arg->reserved = 0;
   127		ipi_arg->cpu_mask = 0;
   128	
   129		for_each_cpu(cur_cpu, mask) {
   130			vcpu = hv_cpu_number_to_vp_number(cur_cpu);
   131			if (vcpu >= 64)
   132				goto ipi_mask_done;
   133	
   134			__set_bit(vcpu, (unsigned long *)&ipi_arg->cpu_mask);
   135		}
   136	
   137		ret = hv_do_hypercall(HVCALL_SEND_IPI, ipi_arg, NULL);
   138	
   139	ipi_mask_done:
   140		local_irq_restore(flags);
   141		return ret;
   142	}
   143	
   144	static int __send_ipi_one(int cpu, int vector)
   145	{
   146		struct cpumask mask = CPU_MASK_NONE;
   147	
   148		cpumask_set_cpu(cpu, &mask);
   149		return __send_ipi_mask(&mask, vector);
   150	}
   151	
   152	static void hv_send_ipi(int cpu, int vector)
   153	{
   154		if (__send_ipi_one(cpu, vector))
 > 155			orig_apic.send_IPI(cpu, vector);
   156	}
   157	
   158	static void hv_send_ipi_mask(const struct cpumask *mask, int vector)
   159	{
   160		if (__send_ipi_mask(mask, vector))
   161			orig_apic.send_IPI_mask(mask, vector);
   162	}
   163	
   164	static void hv_send_ipi_mask_allbutself(const struct cpumask *mask, int vector)
   165	{
   166		unsigned int this_cpu = smp_processor_id();
   167		struct cpumask new_mask;
   168		const struct cpumask *local_mask;
   169	
   170		cpumask_copy(&new_mask, mask);
   171		cpumask_clear_cpu(this_cpu, &new_mask);
   172		local_mask = &new_mask;
   173		if (__send_ipi_mask(local_mask, vector))
   174			orig_apic.send_IPI_mask_allbutself(mask, vector);
   175	}
   176	
   177	static void hv_send_ipi_allbutself(int vector)
   178	{
   179		hv_send_ipi_mask_allbutself(cpu_online_mask, vector);
   180	}
   181	
   182	static void hv_send_ipi_all(int vector)
   183	{
   184		if (__send_ipi_mask(cpu_online_mask, vector))
   185			orig_apic.send_IPI_all(vector);
   186	}
   187	
   188	static void hv_send_ipi_self(int vector)
   189	{
   190		if (__send_ipi_one(smp_processor_id(), vector))
 > 191			orig_apic.send_IPI_self(vector);
   192	}
   193	
   194	void __init hv_apic_init(void)
   195	{
   196		if (ms_hyperv.hints & HV_X64_CLUSTER_IPI_RECOMMENDED) {
   197			if (hyperv_pcpu_input_arg == NULL)
   198				goto msr_based_access;
   199	
   200			pr_info("Hyper-V: Using IPI hypercalls\n");
   201			/*
   202			 * Set the IPI entry points.
   203			 */
 > 204			orig_apic = *apic;

---
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#10 lore raw

Re: [PATCH 2/5] X86: Hyper-V: Enable IPI enlightenments

In reply to [email protected]
I love your patch! Perhaps something to improve:

Hi Srinivasan,

I love your patch! Perhaps something to improve:

[auto build test WARNING on v4.17-rc2]
[also build test WARNING on next-20180426]
[cannot apply to tip/x86/core]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url: https://github.com/0day-ci/linux/commits/kys-linuxonhyperv-com/X86-Hyper-V-APIC-enlightenments/20180427-114416
reproduce:

        # apt-get install sparse
        make ARCH=x86_64 allmodconfig
        make C=1 CF=-D__CHECK_ENDIAN__

sparse warnings: (new ones prefixed by >>)

>> arch/x86/hyperv/hv_init.c:105:30: sparse: incorrect type in initializer (different address spaces) @@    expected void const [noderef] <asn:3>*__vpp_verify @@    got const [noderef] <asn:3>*__vpp_verify @@
   arch/x86/hyperv/hv_init.c:105:30:    expected void const [noderef] <asn:3>*__vpp_verify
   arch/x86/hyperv/hv_init.c:105:30:    got void [noderef] <asn:3>**<noident>
   arch/x86/hyperv/hv_init.c:229:30: sparse: incorrect type in initializer (different address spaces) @@    expected void const [noderef] <asn:3>*__vpp_verify @@    got const [noderef] <asn:3>*__vpp_verify @@
   arch/x86/hyperv/hv_init.c:229:30:    expected void const [noderef] <asn:3>*__vpp_verify
   arch/x86/hyperv/hv_init.c:229:30:    got void [noderef] <asn:3>**<noident>
>> arch/x86/hyperv/hv_init.c:275:31: sparse: incorrect type in assignment (different address spaces) @@    expected void [noderef] <asn:3>**extern [addressable] [toplevel] hyperv_pcpu_input_arg @@    got addressable] [toplevel] hyperv_pcpu_input_arg @@

arch/x86/hyperv/hv_init.c:275:31: expected void [noderef] <asn:3>**extern [addressable] [toplevel] hyperv_pcpu_input_arg
arch/x86/hyperv/hv_init.c:275:31: got void *[noderef] <asn:3>*<noident>
arch/x86/include/asm/paravirt.h:150:9: sparse: cast truncates bits from constant value (8000000000000000 becomes 0)
--

>> arch/x86/hyperv/hv_apic.c:118:41: sparse: incorrect type in initializer (different address spaces) @@    expected void const [noderef] <asn:3>*__vpp_verify @@    got const [noderef] <asn:3>*__vpp_verify @@

arch/x86/hyperv/hv_apic.c:118:41: expected void const [noderef] <asn:3>*__vpp_verify
arch/x86/hyperv/hv_apic.c:118:41: got void [noderef] <asn:3>**<noident>

vim +105 arch/x86/hyperv/hv_init.c

98
99 static int hv_cpu_init(unsigned int cpu)
100 {
101 u64 msr_vp_index;
102 struct hv_vp_assist_page **hvp = &hv_vp_assist_page[smp_processor_id()];
103 void **input_arg;
104

 > 105		input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
   106		*input_arg = page_address(alloc_page(GFP_ATOMIC));
   107	
   108		hv_get_vp_index(msr_vp_index);
   109	
   110		hv_vp_index[smp_processor_id()] = msr_vp_index;
   111	
   112		if (msr_vp_index > hv_max_vp_index)
   113			hv_max_vp_index = msr_vp_index;
   114	
   115		if (!hv_vp_assist_page)
   116			return 0;
   117	
   118		if (!*hvp)
   119			*hvp = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL);
   120	
   121		if (*hvp) {
   122			u64 val;
   123	
   124			val = vmalloc_to_pfn(*hvp);
   125			val = (val << HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_SHIFT) |
   126				HV_X64_MSR_VP_ASSIST_PAGE_ENABLE;
   127	
   128			wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, val);
   129		}
   130	
   131		return 0;
   132	}
   133	
   134	static void (*hv_reenlightenment_cb)(void);
   135	
   136	static void hv_reenlightenment_notify(struct work_struct *dummy)
   137	{
   138		struct hv_tsc_emulation_status emu_status;
   139	
   140		rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
   141	
   142		/* Don't issue the callback if TSC accesses are not emulated */
   143		if (hv_reenlightenment_cb && emu_status.inprogress)
   144			hv_reenlightenment_cb();
   145	}
   146	static DECLARE_DELAYED_WORK(hv_reenlightenment_work, hv_reenlightenment_notify);
   147	
   148	void hyperv_stop_tsc_emulation(void)
   149	{
   150		u64 freq;
   151		struct hv_tsc_emulation_status emu_status;
   152	
   153		rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
   154		emu_status.inprogress = 0;
   155		wrmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
   156	
   157		rdmsrl(HV_X64_MSR_TSC_FREQUENCY, freq);
   158		tsc_khz = div64_u64(freq, 1000);
   159	}
   160	EXPORT_SYMBOL_GPL(hyperv_stop_tsc_emulation);
   161	
   162	static inline bool hv_reenlightenment_available(void)
   163	{
   164		/*
   165		 * Check for required features and priviliges to make TSC frequency
   166		 * change notifications work.
   167		 */
   168		return ms_hyperv.features & HV_X64_ACCESS_FREQUENCY_MSRS &&
   169			ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE &&
   170			ms_hyperv.features & HV_X64_ACCESS_REENLIGHTENMENT;
   171	}
   172	
   173	__visible void __irq_entry hyperv_reenlightenment_intr(struct pt_regs *regs)
   174	{
   175		entering_ack_irq();
   176	
   177		inc_irq_stat(irq_hv_reenlightenment_count);
   178	
   179		schedule_delayed_work(&hv_reenlightenment_work, HZ/10);
   180	
   181		exiting_irq();
   182	}
   183	
   184	void set_hv_tscchange_cb(void (*cb)(void))
   185	{
   186		struct hv_reenlightenment_control re_ctrl = {
   187			.vector = HYPERV_REENLIGHTENMENT_VECTOR,
   188			.enabled = 1,
   189			.target_vp = hv_vp_index[smp_processor_id()]
   190		};
   191		struct hv_tsc_emulation_control emu_ctrl = {.enabled = 1};
   192	
   193		if (!hv_reenlightenment_available()) {
   194			pr_warn("Hyper-V: reenlightenment support is unavailable\n");
   195			return;
   196		}
   197	
   198		hv_reenlightenment_cb = cb;
   199	
   200		/* Make sure callback is registered before we write to MSRs */
   201		wmb();
   202	
   203		wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
   204		wrmsrl(HV_X64_MSR_TSC_EMULATION_CONTROL, *((u64 *)&emu_ctrl));
   205	}
   206	EXPORT_SYMBOL_GPL(set_hv_tscchange_cb);
   207	
   208	void clear_hv_tscchange_cb(void)
   209	{
   210		struct hv_reenlightenment_control re_ctrl;
   211	
   212		if (!hv_reenlightenment_available())
   213			return;
   214	
   215		rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
   216		re_ctrl.enabled = 0;
   217		wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
   218	
   219		hv_reenlightenment_cb = NULL;
   220	}
   221	EXPORT_SYMBOL_GPL(clear_hv_tscchange_cb);
   222	
   223	static int hv_cpu_die(unsigned int cpu)
   224	{
   225		struct hv_reenlightenment_control re_ctrl;
   226		unsigned int new_cpu;
   227		void **input_arg;
   228	
   229		input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
   230		free_page((unsigned long)*input_arg);
   231	
   232		if (hv_vp_assist_page && hv_vp_assist_page[cpu])
   233			wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, 0);
   234	
   235		if (hv_reenlightenment_cb == NULL)
   236			return 0;
   237	
   238		rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
   239		if (re_ctrl.target_vp == hv_vp_index[cpu]) {
   240			/* Reassign to some other online CPU */
   241			new_cpu = cpumask_any_but(cpu_online_mask, cpu);
   242	
   243			re_ctrl.target_vp = hv_vp_index[new_cpu];
   244			wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
   245		}
   246	
   247		return 0;
   248	}
   249	
   250	/*
   251	 * This function is to be invoked early in the boot sequence after the
   252	 * hypervisor has been detected.
   253	 *
   254	 * 1. Setup the hypercall page.
   255	 * 2. Register Hyper-V specific clocksource.
   256	 * 3. Setup Hyper-V specific APIC entry points.
   257	 */
   258	void __init hyperv_init(void)
   259	{
   260		u64 guest_id, required_msrs;
   261		union hv_x64_msr_hypercall_contents hypercall_msr;
   262		int cpuhp;
   263	
   264		if (x86_hyper_type != X86_HYPER_MS_HYPERV)
   265			return;
   266	
   267		/* Absolutely required MSRs */
   268		required_msrs = HV_X64_MSR_HYPERCALL_AVAILABLE |
   269			HV_X64_MSR_VP_INDEX_AVAILABLE;
   270	
   271		if ((ms_hyperv.features & required_msrs) != required_msrs)
   272			return;
   273	
   274		/* Allocate the per-CPU state for the hypercall input arg */
 > 275		hyperv_pcpu_input_arg = alloc_percpu(void  *);

276
277 if (hyperv_pcpu_input_arg == NULL)
278 return;
279
280 /* Allocate percpu VP index */
281 hv_vp_index = kmalloc_array(num_possible_cpus(), sizeof(*hv_vp_index),
282 GFP_KERNEL);
283 if (!hv_vp_index)
284 return;
285
286 hv_vp_assist_page = kcalloc(num_possible_cpus(),
287 sizeof(*hv_vp_assist_page), GFP_KERNEL);
288 if (!hv_vp_assist_page) {
289 ms_hyperv.hints &= ~HV_X64_ENLIGHTENED_VMCS_RECOMMENDED;
290 goto free_vp_index;
291 }
292
293 cpuhp = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/hyperv_init:online",
294 hv_cpu_init, hv_cpu_die);
295 if (cpuhp < 0)
296 goto free_vp_assist_page;
297
298 /*
299 * Setup the hypercall page and enable hypercalls.
300 * 1. Register the guest ID
301 * 2. Enable the hypercall and register the hypercall page
302 */
303 guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0);
304 wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
305
306 hv_hypercall_pg = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL_RX);
307 if (hv_hypercall_pg == NULL) {
308 wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
309 goto remove_cpuhp_state;
310 }
311
312 rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
313 hypercall_msr.enable = 1;
314 hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg);
315 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
316
317 hyper_alloc_mmu();
318
319 hv_apic_init();
320
321 /*
322 * Register Hyper-V specific clocksource.
323 */
324 #ifdef CONFIG_HYPERV_TSCPAGE
325 if (ms_hyperv.features & HV_X64_MSR_REFERENCE_TSC_AVAILABLE) {
326 union hv_x64_msr_hypercall_contents tsc_msr;
327
328 tsc_pg = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL);
329 if (!tsc_pg)
330 goto register_msr_cs;
331
332 hyperv_cs = &hyperv_cs_tsc;
333
334 rdmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
335
336 tsc_msr.enable = 1;
337 tsc_msr.guest_physical_address = vmalloc_to_pfn(tsc_pg);
338
339 wrmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
340
341 hyperv_cs_tsc.archdata.vclock_mode = VCLOCK_HVCLOCK;
342
343 clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100);
344 return;
345 }
346 register_msr_cs:
347 #endif
348 /*
349 * For 32 bit guests just use the MSR based mechanism for reading
350 * the partition counter.
351 */
352
353 hyperv_cs = &hyperv_cs_msr;
354 if (ms_hyperv.features & HV_X64_MSR_TIME_REF_COUNT_AVAILABLE)
355 clocksource_register_hz(&hyperv_cs_msr, NSEC_PER_SEC/100);
356
357 return;
358
359 remove_cpuhp_state:
360 cpuhp_remove_state(cpuhp);
361 free_vp_assist_page:
362 kfree(hv_vp_assist_page);
363 hv_vp_assist_page = NULL;
364 free_vp_index:
365 kfree(hv_vp_index);
366 hv_vp_index = NULL;
367 }
368

---
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#11 lore raw

Re: [PATCH 2/5] X86: Hyper-V: Enable IPI enlightenments

In reply to [email protected]
I love your patch! Yet something to improve:

Hi Srinivasan,

I love your patch! Yet something to improve:

[auto build test ERROR on v4.17-rc2]
[also build test ERROR on next-20180426]
[cannot apply to tip/x86/core]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url: https://github.com/0day-ci/linux/commits/kys-linuxonhyperv-com/X86-Hyper-V-APIC-enlightenments/20180427-114416
config: i386-randconfig-s1-04271426 (attached as .config)
compiler: gcc-6 (Debian 6.4.0-9) 6.4.0 20171026 reproduce:

        # save the attached .config to linux build tree
        make ARCH=i386 

All errors (new ones prefixed by >>):

arch/x86/hyperv/hv_apic.c: In function 'hv_apic_read':
arch/x86/hyperv/hv_apic.c:73:10: error: implicit declaration of function 'native_apic_mem_read' [-Werror=implicit-function-declaration]

      return native_apic_mem_read(reg);
             ^~~~~~~~~~~~~~~~~~~~
   arch/x86/hyperv/hv_apic.c: In function 'hv_apic_write':
   arch/x86/hyperv/hv_apic.c:87:3: error: implicit declaration of function 'native_apic_mem_write' [-Werror=implicit-function-declaration]
      native_apic_mem_write(reg, val);
      ^~~~~~~~~~~~~~~~~~~~~
   arch/x86/hyperv/hv_apic.c: In function 'hv_send_ipi':
   arch/x86/hyperv/hv_apic.c:155:3: error: invalid use of undefined type 'struct apic'
      orig_apic.send_IPI(cpu, vector);
      ^~~~~~~~~
   arch/x86/hyperv/hv_apic.c: In function 'hv_send_ipi_mask':
   arch/x86/hyperv/hv_apic.c:161:3: error: invalid use of undefined type 'struct apic'
      orig_apic.send_IPI_mask(mask, vector);
      ^~~~~~~~~
   arch/x86/hyperv/hv_apic.c: In function 'hv_send_ipi_mask_allbutself':
   arch/x86/hyperv/hv_apic.c:174:3: error: invalid use of undefined type 'struct apic'
      orig_apic.send_IPI_mask_allbutself(mask, vector);
      ^~~~~~~~~
   arch/x86/hyperv/hv_apic.c: In function 'hv_send_ipi_all':
   arch/x86/hyperv/hv_apic.c:185:3: error: invalid use of undefined type 'struct apic'
      orig_apic.send_IPI_all(vector);
      ^~~~~~~~~
   arch/x86/hyperv/hv_apic.c: In function 'hv_send_ipi_self':
   arch/x86/hyperv/hv_apic.c:191:3: error: invalid use of undefined type 'struct apic'
      orig_apic.send_IPI_self(vector);
      ^~~~~~~~~
   arch/x86/hyperv/hv_apic.c: In function 'hv_apic_init':
   arch/x86/hyperv/hv_apic.c:204:16: error: 'apic' undeclared (first use in this function)
      orig_apic = *apic;
                   ^~~~
   arch/x86/hyperv/hv_apic.c:204:16: note: each undeclared identifier is reported only once for each function it appears in
>> arch/x86/hyperv/hv_apic.c:204:3: error: 'orig_apic' has an incomplete type 'struct apic'
      orig_apic = *apic;
      ^~~~~~~~~
   arch/x86/hyperv/hv_apic.c:217:3: error: implicit declaration of function 'apic_set_eoi_write' [-Werror=implicit-function-declaration]
      apic_set_eoi_write(hv_apic_eoi_write);
      ^~~~~~~~~~~~~~~~~~
   arch/x86/hyperv/hv_apic.c: At top level:
>> arch/x86/hyperv/hv_apic.c:39:20: error: storage size of 'orig_apic' isn't known
    static struct apic orig_apic;
                       ^~~~~~~~~

cc1: some warnings being treated as errors

vim +204 arch/x86/hyperv/hv_apic.c

    38	
  > 39	static struct apic orig_apic;
    40	
    41	static u64 hv_apic_icr_read(void)
    42	{
    43		u64 reg_val;
    44	
    45		rdmsrl(HV_X64_MSR_ICR, reg_val);
    46		return reg_val;
    47	}
    48	
    49	static void hv_apic_icr_write(u32 low, u32 id)
    50	{
    51		u64 reg_val;
    52	
    53		reg_val = SET_APIC_DEST_FIELD(id);
    54		reg_val = reg_val << 32;
    55		reg_val |= low;
    56	
    57		wrmsrl(HV_X64_MSR_ICR, reg_val);
    58	}
    59	
    60	static u32 hv_apic_read(u32 reg)
    61	{
    62		u32 reg_val, hi;
    63	
    64		switch (reg) {
    65		case APIC_EOI:
    66			rdmsr(HV_X64_MSR_EOI, reg_val, hi);
    67			return reg_val;
    68		case APIC_TASKPRI:
    69			rdmsr(HV_X64_MSR_TPR, reg_val, hi);
    70			return reg_val;
    71	
    72		default:
    73			return native_apic_mem_read(reg);
    74		}
    75	}
    76	
    77	static void hv_apic_write(u32 reg, u32 val)
    78	{
    79		switch (reg) {
    80		case APIC_EOI:
    81			wrmsr(HV_X64_MSR_EOI, val, 0);
    82			break;
    83		case APIC_TASKPRI:
    84			wrmsr(HV_X64_MSR_TPR, val, 0);
    85			break;
    86		default:
    87			native_apic_mem_write(reg, val);
    88		}
    89	}
    90	
    91	static void hv_apic_eoi_write(u32 reg, u32 val)
    92	{
    93		wrmsr(HV_X64_MSR_EOI, val, 0);
    94	}
    95	
    96	/*
    97	 * IPI implementation on Hyper-V.
    98	 */
    99	
   100	static int __send_ipi_mask(const struct cpumask *mask, int vector)
   101	{
   102		int cur_cpu, vcpu;
   103		struct ipi_arg_non_ex **arg;
   104		struct ipi_arg_non_ex *ipi_arg;
   105		int ret = 1;
   106		unsigned long flags;
   107	
   108		if (cpumask_empty(mask))
   109			return 0;
   110	
   111		if (!hv_hypercall_pg)
   112			return ret;
   113	
   114		if ((vector < HV_IPI_LOW_VECTOR) || (vector > HV_IPI_HIGH_VECTOR))
   115			return ret;
   116	
   117		local_irq_save(flags);
   118		arg = (struct ipi_arg_non_ex **)this_cpu_ptr(hyperv_pcpu_input_arg);
   119	
   120		ipi_arg = *arg;
   121		if (unlikely(!ipi_arg))
   122			goto ipi_mask_done;
   123	
   124	
   125		ipi_arg->vector = vector;
   126		ipi_arg->reserved = 0;
   127		ipi_arg->cpu_mask = 0;
   128	
   129		for_each_cpu(cur_cpu, mask) {
   130			vcpu = hv_cpu_number_to_vp_number(cur_cpu);
   131			if (vcpu >= 64)
   132				goto ipi_mask_done;
   133	
   134			__set_bit(vcpu, (unsigned long *)&ipi_arg->cpu_mask);
   135		}
   136	
   137		ret = hv_do_hypercall(HVCALL_SEND_IPI, ipi_arg, NULL);
   138	
   139	ipi_mask_done:
   140		local_irq_restore(flags);
   141		return ret;
   142	}
   143	
   144	static int __send_ipi_one(int cpu, int vector)
   145	{
   146		struct cpumask mask = CPU_MASK_NONE;
   147	
   148		cpumask_set_cpu(cpu, &mask);
   149		return __send_ipi_mask(&mask, vector);
   150	}
   151	
   152	static void hv_send_ipi(int cpu, int vector)
   153	{
   154		if (__send_ipi_one(cpu, vector))
   155			orig_apic.send_IPI(cpu, vector);
   156	}
   157	
   158	static void hv_send_ipi_mask(const struct cpumask *mask, int vector)
   159	{
   160		if (__send_ipi_mask(mask, vector))
   161			orig_apic.send_IPI_mask(mask, vector);
   162	}
   163	
   164	static void hv_send_ipi_mask_allbutself(const struct cpumask *mask, int vector)
   165	{
   166		unsigned int this_cpu = smp_processor_id();
   167		struct cpumask new_mask;
   168		const struct cpumask *local_mask;
   169	
   170		cpumask_copy(&new_mask, mask);
   171		cpumask_clear_cpu(this_cpu, &new_mask);
   172		local_mask = &new_mask;
   173		if (__send_ipi_mask(local_mask, vector))
   174			orig_apic.send_IPI_mask_allbutself(mask, vector);
   175	}
   176	
   177	static void hv_send_ipi_allbutself(int vector)
   178	{
   179		hv_send_ipi_mask_allbutself(cpu_online_mask, vector);
   180	}
   181	
   182	static void hv_send_ipi_all(int vector)
   183	{
   184		if (__send_ipi_mask(cpu_online_mask, vector))
   185			orig_apic.send_IPI_all(vector);
   186	}
   187	
   188	static void hv_send_ipi_self(int vector)
   189	{
   190		if (__send_ipi_one(smp_processor_id(), vector))
 > 191			orig_apic.send_IPI_self(vector);
   192	}
   193	
   194	void __init hv_apic_init(void)
   195	{
   196		if (ms_hyperv.hints & HV_X64_CLUSTER_IPI_RECOMMENDED) {
   197			if (hyperv_pcpu_input_arg == NULL)
   198				goto msr_based_access;
   199	
   200			pr_info("Hyper-V: Using IPI hypercalls\n");
   201			/*
   202			 * Set the IPI entry points.
   203			 */
 > 204			orig_apic = *apic;

---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation

#12 lore raw

PATCH 3/5 X86: Hyper-V: Enhanced IPI enlightenment

In reply to [email protected]

From: "K. Y. Srinivasan" <[email protected]>

Support enhanced IPI enlightenments (to target more than 64 CPUs).

---
 arch/x86/hyperv/hv_apic.c          | 49 ++++++++++++++++++++++++++++++++++++--
 arch/x86/include/asm/hyperv-tlfs.h |  1 +
 arch/x86/include/asm/mshyperv.h    | 39 ++++++++++++++++++++++++++++++
 3 files changed, 87 insertions(+), 2 deletions(-)
arch/x86/hyperv/hv_apic.c +47 -2
index 7f3322ecfb01..fbb408b91e25 100644
@@ -36,6 +36,12 @@ struct ipi_arg_non_ex {
 	u64 cpu_mask;
 };
 
+struct ipi_arg_ex {
+	u32 vector;
+	u32  reserved;
+	struct hv_vpset vp_set;
+};
+
 static struct apic orig_apic;
 
 static u64 hv_apic_icr_read(void)
@@ -97,6 +103,40 @@ static void hv_apic_eoi_write(u32 reg, u32 val)
  * IPI implementation on Hyper-V.
  */
 
+static int __send_ipi_mask_ex(const struct cpumask *mask, int vector)
+{
+	int nr_bank = 0;
+	struct ipi_arg_ex **arg;
+	struct ipi_arg_ex *ipi_arg;
+	int ret = 1;
+	unsigned long flags;
+
+	local_irq_save(flags);
+	arg = (struct ipi_arg_ex **)this_cpu_ptr(hyperv_pcpu_input_arg);
+
+	ipi_arg = *arg;
+	if (unlikely(!ipi_arg))
+		goto ipi_mask_ex_done;
+
+	ipi_arg->vector = vector;
+	ipi_arg->reserved = 0;
+	ipi_arg->vp_set.valid_bank_mask = 0;
+
+	if (!cpumask_equal(mask, cpu_present_mask)) {
+		ipi_arg->vp_set.format = HV_GENERIC_SET_SPARCE_4K;
+		nr_bank = cpumask_to_vpset(&(ipi_arg->vp_set), mask);
+	}
+	if (!nr_bank)
+		ipi_arg->vp_set.format = HV_GENERIC_SET_ALL;
+
+	ret = hv_do_rep_hypercall(HVCALL_SEND_IPI_EX, 0, nr_bank,
+			      ipi_arg, NULL);
+
+ipi_mask_ex_done:
+	local_irq_restore(flags);
+	return ret;
+}
+
 static int __send_ipi_mask(const struct cpumask *mask, int vector)
 {
 	int cur_cpu, vcpu;
@@ -114,6 +154,9 @@ static int __send_ipi_mask(const struct cpumask *mask, int vector)
 	if ((vector < HV_IPI_LOW_VECTOR) || (vector > HV_IPI_HIGH_VECTOR))
 		return ret;
 
+	if ((ms_hyperv.hints & HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED))
+		return __send_ipi_mask_ex(mask, vector);
+
 	local_irq_save(flags);
 	arg = (struct ipi_arg_non_ex **)this_cpu_ptr(hyperv_pcpu_input_arg);
 
@@ -196,8 +239,10 @@ void __init hv_apic_init(void)
 	if (ms_hyperv.hints & HV_X64_CLUSTER_IPI_RECOMMENDED) {
 		if (hyperv_pcpu_input_arg == NULL)
 			goto msr_based_access;
-
-		pr_info("Hyper-V: Using IPI hypercalls\n");
+		if ((ms_hyperv.hints & HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED))
+			pr_info("Hyper-V: Using ext hypercalls for IPI\n");
+		else
+			pr_info("Hyper-V: Using IPI hypercalls\n");
 		/*
 		 * Set the IPI entry points.
 		 */
arch/x86/include/asm/hyperv-tlfs.h +1 -0
index 646cf2ca2aaa..53ea30d768d9 100644
@@ -344,6 +344,7 @@ struct hv_tsc_emulation_status {
 #define HVCALL_SEND_IPI				0x000b
 #define HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX  0x0013
 #define HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX   0x0014
+#define HVCALL_SEND_IPI_EX			0x0015
 #define HVCALL_POST_MESSAGE			0x005c
 #define HVCALL_SIGNAL_EVENT			0x005d
 
arch/x86/include/asm/mshyperv.h +39 -0
index f6045f3611de..956e8603bed2 100644
@@ -259,6 +259,45 @@ static inline int hv_cpu_number_to_vp_number(int cpu_number)
 	return hv_vp_index[cpu_number];
 }
 
+struct hv_vpset {
+	u64 format;
+	u64 valid_bank_mask;
+	u64 bank_contents[];
+};
+
+static inline int cpumask_to_vpset(struct hv_vpset *vpset,
+				    const struct cpumask *cpus)
+{
+	int cpu, vcpu, vcpu_bank, vcpu_offset, nr_bank = 1;
+
+	/* valid_bank_mask can represent up to 64 banks */
+	if (hv_max_vp_index / 64 >= 64)
+		return 0;
+
+	/*
+	 * Clear all banks up to the maximum possible bank as hv_flush_pcpu_ex
+	 * structs are not cleared between calls, we risk flushing unneeded
+	 * vCPUs otherwise.
+	 */
+	for (vcpu_bank = 0; vcpu_bank <= hv_max_vp_index / 64; vcpu_bank++)
+		vpset->bank_contents[vcpu_bank] = 0;
+
+	/*
+	 * Some banks may end up being empty but this is acceptable.
+	 */
+	for_each_cpu(cpu, cpus) {
+		vcpu = hv_cpu_number_to_vp_number(cpu);
+		vcpu_bank = vcpu / 64;
+		vcpu_offset = vcpu % 64;
+		__set_bit(vcpu_offset, (unsigned long *)
+			  &vpset->bank_contents[vcpu_bank]);
+		if (vcpu_bank >= nr_bank)
+			nr_bank = vcpu_bank + 1;
+	}
+	vpset->valid_bank_mask = GENMASK_ULL(nr_bank - 1, 0);
+	return nr_bank;
+}
+
 void __init hyperv_init(void);
 void hyperv_setup_mmu_ops(void);
 void hyper_alloc_mmu(void);
Signature · 1 line
2.15.1
#13 lore raw

Re: [PATCH 3/5] X86: Hyper-V: Enhanced IPI enlightenment

arch/x86/hyperv/hv_apic.c struct ipi_arg_non_ex { · line 42

Quoted 5 lines · On Wed, 25 Apr 2018, [email protected] wrote:
arch/x86/hyperv/hv_apic.c +4 -0
+struct ipi_arg_ex {
+	u32 vector;
+	u32  reserved;
+	struct hv_vpset vp_set;

Please align that in tabular fashion for easy of reading

	u32		vector;
	u32  		reserved;
	struct hv_vpset	vp_set;
Quoted 6 lines
arch/x86/hyperv/hv_apic.c +2 -0
+};
+
 static struct apic orig_apic;
 
 static u64 hv_apic_icr_read(void)

arch/x86/hyperv/hv_apic.c static void hv_apic_eoi_write(u32 reg, u32 val) · line 112

Quoted 10 lines
arch/x86/hyperv/hv_apic.c +7 -0
@@ -97,6 +103,40 @@ static void hv_apic_eoi_write(u32 reg, u32 val)
  * IPI implementation on Hyper-V.
  */
 
+static int __send_ipi_mask_ex(const struct cpumask *mask, int vector)
+{
+	int nr_bank = 0;
+	struct ipi_arg_ex **arg;
+	struct ipi_arg_ex *ipi_arg;
+	int ret = 1;
+	unsigned long flags;

This is really horrible to read.

	struct ipi_arg_ex *ipi_arg;
	struct ipi_arg_ex **arg;
	unsigned long flags;
	bool ret = false;
	int nr_bank = 0;

is really more conveniant for quick reading.

So the other more limited function has a lot more sanity checks vs. vector number and other things. Why are they not required here? Comment please.

Quoted 4 lines
arch/x86/hyperv/hv_apic.c +4 -0
+	local_irq_save(flags);
+	arg = (struct ipi_arg_ex **)this_cpu_ptr(hyperv_pcpu_input_arg);
+
+	ipi_arg = *arg;

arch/x86/hyperv/hv_apic.c static void hv_apic_eoi_write(u32 reg, u32 val) · line 127

Quoted 10 lines
arch/x86/hyperv/hv_apic.c +10 -0
+	if (unlikely(!ipi_arg))
+		goto ipi_mask_ex_done;
+
+	ipi_arg->vector = vector;
+	ipi_arg->reserved = 0;
+	ipi_arg->vp_set.valid_bank_mask = 0;
+
+	if (!cpumask_equal(mask, cpu_present_mask)) {
+		ipi_arg->vp_set.format = HV_GENERIC_SET_SPARCE_4K;
+		nr_bank = cpumask_to_vpset(&(ipi_arg->vp_set), mask);

nr_bank really confused me. bank_nr is what you mean, not number of banks, right?

arch/x86/hyperv/hv_apic.c static void hv_apic_eoi_write(u32 reg, u32 val) · line 138

Quoted 11 lines
arch/x86/hyperv/hv_apic.c +11 -0
+	}
+	if (!nr_bank)
+		ipi_arg->vp_set.format = HV_GENERIC_SET_ALL;
+
+	ret = hv_do_rep_hypercall(HVCALL_SEND_IPI_EX, 0, nr_bank,
+			      ipi_arg, NULL);
+
+ipi_mask_ex_done:
+	local_irq_restore(flags);
+	return ret;
+}

Thanks,

tglx
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devel mailing list
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http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel

#14 lore raw

RE: [PATCH 3/5] X86: Hyper-V: Enhanced IPI enlightenment

Quoted 51 lines

-----Original Message-----
From: Thomas Gleixner <[email protected]>
Sent: Thursday, April 26, 2018 3:17 PM
To: KY Srinivasan <[email protected]>
Cc: [email protected]; [email protected]; linux- [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; Stephen Hemminger <[email protected]>; Michael Kelley (EOSG) <[email protected]>; [email protected]
Subject: Re: [PATCH 3/5] X86: Hyper-V: Enhanced IPI enlightenment

arch/x86/hyperv/hv_apic.c struct ipi_arg_non_ex { · line 42

Quoted 5 lines · On Wed, 25 Apr 2018, [email protected] wrote:
arch/x86/hyperv/hv_apic.c +4 -0
+struct ipi_arg_ex {
+	u32 vector;
+	u32  reserved;
+	struct hv_vpset vp_set;

Please align that in tabular fashion for easy of reading

	u32		vector;
	u32  		reserved;
	struct hv_vpset	vp_set;
Quoted 6 lines
arch/x86/hyperv/hv_apic.c +2 -0
+};
+
 static struct apic orig_apic;
 
 static u64 hv_apic_icr_read(void)

arch/x86/hyperv/hv_apic.c static void hv_apic_eoi_write(u32 reg, u32 val) · line 112

Quoted 10 lines
arch/x86/hyperv/hv_apic.c +7 -0
@@ -97,6 +103,40 @@ static void hv_apic_eoi_write(u32 reg, u32 val)
  * IPI implementation on Hyper-V.
  */
 
+static int __send_ipi_mask_ex(const struct cpumask *mask, int vector)
+{
+	int nr_bank = 0;
+	struct ipi_arg_ex **arg;
+	struct ipi_arg_ex *ipi_arg;
+	int ret = 1;
+	unsigned long flags;

This is really horrible to read.

	struct ipi_arg_ex *ipi_arg;
	struct ipi_arg_ex **arg;
	unsigned long flags;
	bool ret = false;
	int nr_bank = 0;
Quoted 5 lines

is really more conveniant for quick reading.

So the other more limited function has a lot more sanity checks vs. vector number and other things. Why are they not required here? Comment please.

Yes, I will add the comments. This function is called from the other function after all the sanity checks have been done and hence are not replicated here.

Quoted 11 lines
Quoted 11 lines
arch/x86/hyperv/hv_apic.c +10 -0
+	local_irq_save(flags);
+	arg = (struct ipi_arg_ex **)this_cpu_ptr(hyperv_pcpu_input_arg);
+
+	ipi_arg = *arg;
+	if (unlikely(!ipi_arg))
+		goto ipi_mask_ex_done;
+
+	ipi_arg->vector = vector;
+	ipi_arg->reserved = 0;
+	ipi_arg->vp_set.valid_bank_mask = 0;
Quoted 8 lines

arch/x86/hyperv/hv_apic.c static void hv_apic_eoi_write(u32 reg, u32 val) · line 127

Quoted 4 lines
arch/x86/hyperv/hv_apic.c +4 -0
+
+	if (!cpumask_equal(mask, cpu_present_mask)) {
+		ipi_arg->vp_set.format = HV_GENERIC_SET_SPARCE_4K;
+		nr_bank = cpumask_to_vpset(&(ipi_arg->vp_set), mask);

nr_bank really confused me. bank_nr is what you mean, not number of banks,
right?

It is the number of banks. The hypercall used here is a variable length hypercall.

Regards,

K. Y
_______________________________________________
devel mailing list
[email protected]
http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel

#15 lore raw

RE: [PATCH 3/5] X86: Hyper-V: Enhanced IPI enlightenment

In reply to [email protected]

arch/x86/hyperv/hv_apic.c struct ipi_arg_non_ex { · line 43

Quoted 6 lines · KY Srinivasan
arch/x86/hyperv/hv_apic.c +5 -0
+struct ipi_arg_ex {
+	u32 vector;
+	u32  reserved;
+	struct hv_vpset vp_set;
+};

Again, suggest moving to hyperv-tlfs.h. And the 5.0b version of the TLFS has:

	u32		vector;
	u8		targetvtl;
	u8		reserved[3];
	struct hv_vpset	vp_set;

....

arch/x86/include/asm/mshyperv.h static inline int hv_cpu_number_to_vp_number(int cpu_number) · line 266

Quoted 6 lines
arch/x86/include/asm/mshyperv.h +5 -0
+struct hv_vpset {
+	u64 format;
+	u64 valid_bank_mask;
+	u64 bank_contents[];
+};

And this as well.

Michael
_______________________________________________
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http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel

#16 lore raw

PATCH 4/5 X86: Hyper-V: Consolidate code for converting cpumask to vpset

In reply to [email protected]

From: "K. Y. Srinivasan" <[email protected]>

Consolidate code for converting cpumask to vpset.

---
 arch/x86/hyperv/hv_apic.c          |  2 +-
 arch/x86/hyperv/mmu.c              | 45 +++-----------------------------------
 arch/x86/include/asm/hyperv-tlfs.h |  2 +-
 3 files changed, 5 insertions(+), 44 deletions(-)
arch/x86/hyperv/hv_apic.c +1 -1
index fbb408b91e25..508889c8499e 100644
@@ -123,7 +123,7 @@ static int __send_ipi_mask_ex(const struct cpumask *mask, int vector)
 	ipi_arg->vp_set.valid_bank_mask = 0;
 
 	if (!cpumask_equal(mask, cpu_present_mask)) {
-		ipi_arg->vp_set.format = HV_GENERIC_SET_SPARCE_4K;
+		ipi_arg->vp_set.format = HV_GENERIC_SET_SPARSE_4K;
 		nr_bank = cpumask_to_vpset(&(ipi_arg->vp_set), mask);
 	}
 	if (!nr_bank)
arch/x86/hyperv/mmu.c +3 -42

63 lines not on this page · raw message

arch/x86/include/asm/hyperv-tlfs.h +1 -1
index 53ea30d768d9..b32b87945538 100644
@@ -370,7 +370,7 @@ struct hv_tsc_emulation_status {
 #define HV_FLUSH_USE_EXTENDED_RANGE_FORMAT	BIT(3)
 
 enum HV_GENERIC_SET_FORMAT {
-	HV_GENERIC_SET_SPARCE_4K,
+	HV_GENERIC_SET_SPARSE_4K,
 	HV_GENERIC_SET_ALL,
 };
 
Signature · 1 line
2.15.1
#17 lore raw

Re: [PATCH 4/5] X86: Hyper-V: Consolidate code for converting cpumask to vpset

arch/x86/hyperv/hv_apic.c static int __send_ipi_mask_ex(const struct cpumask *mask, int vector) · line 126

Quoted 4 lines · On Wed, 25 Apr 2018, [email protected] wrote:
arch/x86/hyperv/hv_apic.c +1 -1
 	if (!cpumask_equal(mask, cpu_present_mask)) {
-		ipi_arg->vp_set.format = HV_GENERIC_SET_SPARCE_4K;
+		ipi_arg->vp_set.format = HV_GENERIC_SET_SPARSE_4K;

Please move this patch before the others, so you can use SPARSE in the new code right away.

Thanks,

tglx
_______________________________________________
devel mailing list
[email protected]
http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel

#18 lore raw

PATCH 5/5 X86: Hyper-V: Consolidate the allocation of the hypercall input page

In reply to [email protected]

From: "K. Y. Srinivasan" <[email protected]>

Consolidate the allocation of the hypercall input page.

---
 arch/x86/hyperv/hv_init.c       |  2 --
 arch/x86/hyperv/mmu.c           | 33 +++++++++------------------------
 arch/x86/include/asm/mshyperv.h |  1 -
 3 files changed, 9 insertions(+), 27 deletions(-)
arch/x86/hyperv/hv_init.c +0 -2
index a895662b6b4c..72befd0e2c35 100644
@@ -314,8 +314,6 @@ void __init hyperv_init(void)
 	hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg);
 	wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 
-	hyper_alloc_mmu();
-
 	hv_apic_init();
 
 	/*
arch/x86/hyperv/mmu.c +9 -24
index c9cd28f0bae4..c4466af72e77 100644
@@ -32,9 +32,6 @@ struct hv_flush_pcpu_ex {
 /* Each gva in gva_list encodes up to 4096 pages to flush */
 #define HV_TLB_FLUSH_UNIT (4096 * PAGE_SIZE)
 
-static struct hv_flush_pcpu __percpu **pcpu_flush;
-
-static struct hv_flush_pcpu_ex __percpu **pcpu_flush_ex;
 
 /*
  * Fills in gva_list starting from offset. Returns the number of items added.
@@ -77,7 +74,7 @@ static void hyperv_flush_tlb_others(const struct cpumask *cpus,
 
 	trace_hyperv_mmu_flush_tlb_others(cpus, info);
 
-	if (!pcpu_flush || !hv_hypercall_pg)
+	if (!hv_hypercall_pg)
 		goto do_native;
 
 	if (cpumask_empty(cpus))
@@ -85,10 +82,8 @@ static void hyperv_flush_tlb_others(const struct cpumask *cpus,
 
 	local_irq_save(flags);
 
-	flush_pcpu = this_cpu_ptr(pcpu_flush);
-
-	if (unlikely(!*flush_pcpu))
-		*flush_pcpu = page_address(alloc_page(GFP_ATOMIC));
+	flush_pcpu = (struct hv_flush_pcpu **)
+		     this_cpu_ptr(hyperv_pcpu_input_arg);
 
 	flush = *flush_pcpu;
 
@@ -164,7 +159,7 @@ static void hyperv_flush_tlb_others_ex(const struct cpumask *cpus,
 
 	trace_hyperv_mmu_flush_tlb_others(cpus, info);
 
-	if (!pcpu_flush_ex || !hv_hypercall_pg)
+	if (!hv_hypercall_pg)
 		goto do_native;
 
 	if (cpumask_empty(cpus))
@@ -172,10 +167,8 @@ static void hyperv_flush_tlb_others_ex(const struct cpumask *cpus,
 
 	local_irq_save(flags);
 
-	flush_pcpu = this_cpu_ptr(pcpu_flush_ex);
-
-	if (unlikely(!*flush_pcpu))
-		*flush_pcpu = page_address(alloc_page(GFP_ATOMIC));
+	flush_pcpu = (struct hv_flush_pcpu_ex **)
+		     this_cpu_ptr(hyperv_pcpu_input_arg);
 
 	flush = *flush_pcpu;
 
@@ -249,6 +242,9 @@ void hyperv_setup_mmu_ops(void)
 	if (!(ms_hyperv.hints & HV_X64_REMOTE_TLB_FLUSH_RECOMMENDED))
 		return;
 
+	if (hyperv_pcpu_input_arg == NULL)
+		return;
+
 	if (!(ms_hyperv.hints & HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED)) {
 		pr_info("Using hypercall for remote TLB flush\n");
 		pv_mmu_ops.flush_tlb_others = hyperv_flush_tlb_others;
@@ -257,14 +253,3 @@ void hyperv_setup_mmu_ops(void)
 		pv_mmu_ops.flush_tlb_others = hyperv_flush_tlb_others_ex;
 	}
 }
-
-void hyper_alloc_mmu(void)
-{
-	if (!(ms_hyperv.hints & HV_X64_REMOTE_TLB_FLUSH_RECOMMENDED))
-		return;
-
-	if (!(ms_hyperv.hints & HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED))
-		pcpu_flush = alloc_percpu(struct hv_flush_pcpu *);
-	else
-		pcpu_flush_ex = alloc_percpu(struct hv_flush_pcpu_ex *);
-}
arch/x86/include/asm/mshyperv.h +0 -1
index 956e8603bed2..9931f9908fe2 100644
@@ -300,7 +300,6 @@ static inline int cpumask_to_vpset(struct hv_vpset *vpset,
 
 void __init hyperv_init(void);
 void hyperv_setup_mmu_ops(void);
-void hyper_alloc_mmu(void);
 void hyperv_report_panic(struct pt_regs *regs, long err);
 bool hv_is_hyperv_initialized(void);
 void hyperv_cleanup(void);
Signature · 1 line
2.15.1
#19 lore raw

Re: [PATCH 5/5] X86: Hyper-V: Consolidate the allocation of the hypercall input page

Quoted 3 lines · On Wed, 25 Apr 2018, [email protected] wrote:

From: "K. Y. Srinivasan" <[email protected]>

Consolidate the allocation of the hypercall input page.

Again. You can provide the new way of allocation first, then you don't have to add code first in order to remove it later again.

Thanks,

tglx
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#20 lore raw

RE: [PATCH 5/5] X86: Hyper-V: Consolidate the allocation of the hypercall input page

Quoted 14 lines

-----Original Message-----
From: Thomas Gleixner <[email protected]>
Sent: Thursday, April 26, 2018 3:24 PM
To: KY Srinivasan <[email protected]>
Cc: [email protected]; [email protected]; linux- [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; Stephen Hemminger <[email protected]>; Michael Kelley (EOSG) <[email protected]>; [email protected]
Subject: Re: [PATCH 5/5] X86: Hyper-V: Consolidate the allocation of the hypercall input page

Quoted 8 lines
Quoted 3 lines · On Wed, 25 Apr 2018, [email protected] wrote:

From: "K. Y. Srinivasan" <[email protected]>

Consolidate the allocation of the hypercall input page.

Again. You can provide the new way of allocation first, then you don't have to add code first in order to remove it later again.

I have implemented the new way upfront for the new code - the IPI code [PATCH 2/5] X86: Hyper-V: Enable IPI enlightenments.
What I am doing here using that infrastructure for the TLB flush enlightenments and getting rid of unnecessary code.

Regards,

K. Y
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#21 lore raw

RE: [PATCH 5/5] X86: Hyper-V: Consolidate the allocation of the hypercall input page

Quoted 20 lines · KY Srinivasan
Quoted 20 lines

-----Original Message-----
From: Thomas Gleixner <[email protected]>
Sent: Thursday, April 26, 2018 3:24 PM
To: KY Srinivasan <[email protected]>
Cc: [email protected]; [email protected]; linux- [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; Stephen Hemminger <[email protected]>; Michael Kelley (EOSG) <[email protected]>; [email protected]
Subject: Re: [PATCH 5/5] X86: Hyper-V: Consolidate the allocation of the hypercall input page

Quoted 3 lines · On Wed, 25 Apr 2018, [email protected] wrote:

From: "K. Y. Srinivasan" <[email protected]>

Consolidate the allocation of the hypercall input page.

Quoted 7 lines
Quoted 2 lines

Again. You can provide the new way of allocation first, then you don't have to add code first in order to remove it later again.

I have implemented the new way upfront for the new code - the IPI code [PATCH 2/5] X86: Hyper-V: Enable IPI enlightenments.
What I am doing here using that infrastructure for the TLB flush enlightenments and getting rid of unnecessary code.

Ok. I maybe misread it, but a bit more elaborate change log might help to avoid that.

Thanks,

tglx

#22 lore raw

Re: [PATCH 5/5] X86: Hyper-V: Consolidate the allocation of the hypercall input page

In reply to [email protected]
I love your patch! Perhaps something to improve:

Hi Srinivasan,

I love your patch! Perhaps something to improve:

[auto build test WARNING on v4.17-rc2]
[also build test WARNING on next-20180426]
[cannot apply to tip/x86/core]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url: https://github.com/0day-ci/linux/commits/kys-linuxonhyperv-com/X86-Hyper-V-APIC-enlightenments/20180427-114416
reproduce:

        # apt-get install sparse
        make ARCH=x86_64 allmodconfig
        make C=1 CF=-D__CHECK_ENDIAN__

sparse warnings: (new ones prefixed by >>)

>> arch/x86/hyperv/mmu.c:86:22: sparse: incorrect type in initializer (different address spaces) @@    expected void const [noderef] <asn:3>*__vpp_verify @@    got const [noderef] <asn:3>*__vpp_verify @@

arch/x86/hyperv/mmu.c:86:22: expected void const [noderef] <asn:3>*__vpp_verify
arch/x86/hyperv/mmu.c:86:22: got void [noderef] <asn:3>**<noident>
arch/x86/hyperv/mmu.c:171:22: sparse: incorrect type in initializer (different address spaces) @@ expected void const [noderef] <asn:3>*__vpp_verify @@ got const [noderef] <asn:3>*__vpp_verify @@
arch/x86/hyperv/mmu.c:171:22: expected void const [noderef] <asn:3>*__vpp_verify
arch/x86/hyperv/mmu.c:171:22: got void [noderef] <asn:3>**<noident>

vim +86 arch/x86/hyperv/mmu.c

    65	
    66	static void hyperv_flush_tlb_others(const struct cpumask *cpus,
    67					    const struct flush_tlb_info *info)
    68	{
    69		int cpu, vcpu, gva_n, max_gvas;
    70		struct hv_flush_pcpu **flush_pcpu;
    71		struct hv_flush_pcpu *flush;
    72		u64 status = U64_MAX;
    73		unsigned long flags;
    74	
    75		trace_hyperv_mmu_flush_tlb_others(cpus, info);
    76	
    77		if (!hv_hypercall_pg)
    78			goto do_native;
    79	
    80		if (cpumask_empty(cpus))
    81			return;
    82	
    83		local_irq_save(flags);
    84	
    85		flush_pcpu = (struct hv_flush_pcpu **)
  > 86			     this_cpu_ptr(hyperv_pcpu_input_arg);
    87	
    88		flush = *flush_pcpu;
    89	
    90		if (unlikely(!flush)) {
    91			local_irq_restore(flags);
    92			goto do_native;
    93		}
    94	
    95		if (info->mm) {
    96			/*
    97			 * AddressSpace argument must match the CR3 with PCID bits
    98			 * stripped out.
    99			 */

100 flush->address_space = virt_to_phys(info->mm->pgd);
101 flush->address_space &= CR3_ADDR_MASK;
102 flush->flags = 0;
103 } else {
104 flush->address_space = 0;
105 flush->flags = HV_FLUSH_ALL_VIRTUAL_ADDRESS_SPACES;
106 }
107
108 flush->processor_mask = 0;
109 if (cpumask_equal(cpus, cpu_present_mask)) {
110 flush->flags |= HV_FLUSH_ALL_PROCESSORS;
111 } else {
112 for_each_cpu(cpu, cpus) {
113 vcpu = hv_cpu_number_to_vp_number(cpu);
114 if (vcpu >= 64)
115 goto do_native;
116
117 __set_bit(vcpu, (unsigned long *)
118 &flush->processor_mask);
119 }
120 }
121
122 /*
123 * We can flush not more than max_gvas with one hypercall. Flush the
124 * whole address space if we were asked to do more.
125 */
126 max_gvas = (PAGE_SIZE - sizeof(*flush)) / sizeof(flush->gva_list[0]);
127
128 if (info->end == TLB_FLUSH_ALL) {
129 flush->flags |= HV_FLUSH_NON_GLOBAL_MAPPINGS_ONLY;
130 status = hv_do_hypercall(HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE,
131 flush, NULL);
132 } else if (info->end &&
133 ((info->end - info->start)/HV_TLB_FLUSH_UNIT) > max_gvas) {
134 status = hv_do_hypercall(HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE,
135 flush, NULL);
136 } else {
137 gva_n = fill_gva_list(flush->gva_list, 0,
138 info->start, info->end);
139 status = hv_do_rep_hypercall(HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST,
140 gva_n, 0, flush, NULL);
141 }
142
143 local_irq_restore(flags);
144
145 if (!(status & HV_HYPERCALL_RESULT_MASK))
146 return;
147 do_native:
148 native_flush_tlb_others(cpus, info);
149 }
150

---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation

#23 lore raw

Re: [PATCH 1/5] X86: Hyper-V: Enlighten APIC access

In reply to [email protected]

arch/x86/hyperv/hv_apic.c line 1

Quoted 4 lines · On Wed, 25 Apr 2018, [email protected] wrote:
arch/x86/hyperv/hv_apic.c new file +1 -0
@@ -0,0 +1,98 @@
+// SPDX-License-Identifier: GPL-2.0

Thanks for putting the license identifier in.

arch/x86/hyperv/hv_apic.c line 8

Quoted 7 lines
arch/x86/hyperv/hv_apic.c new file +7 -0
+
+/*
+ * Hyper-V specific APIC code.
+ *
+ * Copyright (C) 2018, Microsoft, Inc.
+ *
+ * Author : K. Y. Srinivasan <[email protected]>

But can you please check with your lawyers whether you can avoid the pointless boilerplate? The SPDX identifier should cover it.

Quoted 12 lines
arch/x86/hyperv/hv_apic.c new file +12 -0
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ * NON INFRINGEMENT.  See the GNU General Public License for more
+ * details.
+ *
+ */
+

arch/x86/hyperv/hv_apic.c line 31

Quoted 10 lines
arch/x86/hyperv/hv_apic.c new file +10 -0
+#include <linux/types.h>
+#include <asm/hypervisor.h>
+#include <asm/mshyperv.h>
+#include <linux/version.h>
+#include <linux/vmalloc.h>
+#include <linux/mm.h>
+#include <linux/clockchips.h>
+#include <linux/hyperv.h>
+#include <linux/slab.h>
+#include <linux/cpuhotplug.h>

We usually order the includes

#include <linux/....>
...
#include <linux/....>

#include <asm/....>
#include <asm/....>

arch/x86/hyperv/hv_apic.c void hyperv_reenlightenment_intr(struct pt_regs *regs); · line 274

Quoted 13 lines
arch/x86/hyperv/hv_apic.c new file +3 -2
-void hyperv_init(void);
+void __init hyperv_init(void);
 void hyperv_setup_mmu_ops(void);
 void hyper_alloc_mmu(void);
 void hyperv_report_panic(struct pt_regs *regs, long err);
@@ -269,14 +269,16 @@ void hyperv_reenlightenment_intr(struct pt_regs *regs);
 void set_hv_tscchange_cb(void (*cb)(void));
 void clear_hv_tscchange_cb(void);
 void hyperv_stop_tsc_emulation(void);
+void hv_apic_init(void);
 #else /* CONFIG_HYPERV */
-static inline void hyperv_init(void) {}
+static __init  inline void hyperv_init(void) {}

The __init on the empty inline function is pointless.

Other than the few nits. This looks well done!

Thanks,

tglx
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#24 lore raw

RE: [PATCH 1/5] X86: Hyper-V: Enlighten APIC access

Quoted 21 lines

-----Original Message-----
From: Thomas Gleixner <[email protected]>
Sent: Thursday, April 26, 2018 2:49 PM
To: KY Srinivasan <[email protected]>
Cc: [email protected]; [email protected]; linux- [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; Stephen Hemminger <[email protected]>; Michael Kelley (EOSG) <[email protected]>; [email protected]
Subject: Re: [PATCH 1/5] X86: Hyper-V: Enlighten APIC access

arch/x86/hyperv/hv_apic.c line 1

Quoted 4 lines · On Wed, 25 Apr 2018, [email protected] wrote:
arch/x86/hyperv/hv_apic.c new file +1 -0
@@ -0,0 +1,98 @@
+// SPDX-License-Identifier: GPL-2.0

Thanks for putting the license identifier in.

Quoted 10 lines

arch/x86/hyperv/hv_apic.c line 8

Quoted 7 lines
arch/x86/hyperv/hv_apic.c new file +7 -0
+
+/*
+ * Hyper-V specific APIC code.
+ *
+ * Copyright (C) 2018, Microsoft, Inc.
+ *
+ * Author : K. Y. Srinivasan <[email protected]>

But can you please check with your lawyers whether you can avoid the pointless boilerplate? The SPDX identifier should cover it.

I will consult with MSFT legal on this.

Quoted 53 lines

arch/x86/hyperv/hv_apic.c line 10

Quoted 3 lines
arch/x86/hyperv/hv_apic.c new file +2 -0
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as

published

arch/x86/hyperv/hv_apic.c

Quoted 5 lines
arch/x86/hyperv/hv_apic.c new file +5 -0
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD

TITLE or

Quoted 5 lines
arch/x86/hyperv/hv_apic.c new file +5 -0
+ * NON INFRINGEMENT.  See the GNU General Public License for more
+ * details.
+ *
+ */
+

arch/x86/hyperv/hv_apic.c line 31

Quoted 10 lines
arch/x86/hyperv/hv_apic.c new file +10 -0
+#include <linux/types.h>
+#include <asm/hypervisor.h>
+#include <asm/mshyperv.h>
+#include <linux/version.h>
+#include <linux/vmalloc.h>
+#include <linux/mm.h>
+#include <linux/clockchips.h>
+#include <linux/hyperv.h>
+#include <linux/slab.h>
+#include <linux/cpuhotplug.h>

We usually order the includes

#include <linux/....>
...
#include <linux/....>

#include <asm/....>
#include <asm/....>

arch/x86/hyperv/hv_apic.c void hyperv_reenlightenment_intr(struct pt_regs

Quoted 6 lines
arch/x86/hyperv/hv_apic.c new file +1 -1
-void hyperv_init(void);
+void __init hyperv_init(void);
 void hyperv_setup_mmu_ops(void);
 void hyper_alloc_mmu(void);
 void hyperv_report_panic(struct pt_regs *regs, long err);
@@ -269,14 +269,16 @@ void hyperv_reenlightenment_intr(struct pt_regs

*regs);

arch/x86/hyperv/hv_apic.c void hyperv_reenlightenment_intr(struct pt_regs · line 274

Quoted 7 lines
arch/x86/hyperv/hv_apic.c new file +2 -1
 void set_hv_tscchange_cb(void (*cb)(void));
 void clear_hv_tscchange_cb(void);
 void hyperv_stop_tsc_emulation(void);
+void hv_apic_init(void);
 #else /* CONFIG_HYPERV */
-static inline void hyperv_init(void) {}
+static __init  inline void hyperv_init(void) {}

The __init on the empty inline function is pointless.

Quoted 1 line

Other than the few nits. This looks well done!

Thanks Thomas. I will address all the issues you have brought up in the next version.

Regards,

K. Y
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#25 lore raw

RE: [PATCH 1/5] X86: Hyper-V: Enlighten APIC access

In reply to [email protected]
Quoted 118 lines

-----Original Message-----
From: [email protected] <[email protected]>
Sent: Wednesday, April 25, 2018 11:13 AM
To: [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; Stephen Hemminger <[email protected]>; Michael Kelley (EOSG) <[email protected]>; [email protected]
Cc: KY Srinivasan <[email protected]>
Subject: [PATCH 1/5] X86: Hyper-V: Enlighten APIC access

From: "K. Y. Srinivasan" <[email protected]>

Hyper-V supports MSR based APIC access; implement
the enlightenment.

---
 arch/x86/hyperv/Makefile        |  2 +-
 arch/x86/hyperv/hv_apic.c       | 98 +++++++++++++++++++++++++++++++++++++++++
 arch/x86/hyperv/hv_init.c       |  5 ++-
 arch/x86/include/asm/mshyperv.h |  6 ++-
 4 files changed, 107 insertions(+), 4 deletions(-)
 create mode 100644 arch/x86/hyperv/hv_apic.c
arch/x86/hyperv/Makefile +1 -1
index 367a8203cfcf..00ce4df01a09 100644
@@ -1 +1 @@
-obj-y		:= hv_init.o mmu.o
+obj-y		:= hv_init.o mmu.o hv_apic.o
arch/x86/hyperv/hv_apic.c new file +81 -0
new file mode 100644
index 000000000000..e0a5b36208fc
@@ -0,0 +1,98 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Hyper-V specific APIC code.
+ *
+ * Copyright (C) 2018, Microsoft, Inc.
+ *
+ * Author : K. Y. Srinivasan <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ * NON INFRINGEMENT.  See the GNU General Public License for more
+ * details.
+ *
+ */
+
+#include <linux/types.h>
+#include <asm/hypervisor.h>
+#include <asm/mshyperv.h>
+#include <linux/version.h>
+#include <linux/vmalloc.h>
+#include <linux/mm.h>
+#include <linux/clockchips.h>
+#include <linux/hyperv.h>
+#include <linux/slab.h>
+#include <linux/cpuhotplug.h>
+
+static u64 hv_apic_icr_read(void)
+{
+	u64 reg_val;
+
+	rdmsrl(HV_X64_MSR_ICR, reg_val);
+	return reg_val;
+}
+
+static void hv_apic_icr_write(u32 low, u32 id)
+{
+	u64 reg_val;
+
+	reg_val = SET_APIC_DEST_FIELD(id);
+	reg_val = reg_val << 32;
+	reg_val |= low;
+
+	wrmsrl(HV_X64_MSR_ICR, reg_val);
+}
+
+static u32 hv_apic_read(u32 reg)
+{
+	u32 reg_val, hi;
+
+	switch (reg) {
+	case APIC_EOI:
+		rdmsr(HV_X64_MSR_EOI, reg_val, hi);
+		return reg_val;
+	case APIC_TASKPRI:
+		rdmsr(HV_X64_MSR_TPR, reg_val, hi);
+		return reg_val;
+
+	default:
+		return native_apic_mem_read(reg);
+	}
+}
+
+static void hv_apic_write(u32 reg, u32 val)
+{
+	switch (reg) {
+	case APIC_EOI:
+		wrmsr(HV_X64_MSR_EOI, val, 0);
+		break;
+	case APIC_TASKPRI:
+		wrmsr(HV_X64_MSR_TPR, val, 0);
+		break;
+	default:
+		native_apic_mem_write(reg, val);
+	}
+}

arch/x86/hyperv/hv_apic.c line 91

Quoted 10 lines
arch/x86/hyperv/hv_apic.c new file +10 -0
+
+static void hv_apic_eoi_write(u32 reg, u32 val)
+{
+	wrmsr(HV_X64_MSR_EOI, val, 0);
+}
+
+void __init hv_apic_init(void)
+{
+	if (ms_hyperv.hints & HV_X64_APIC_ACCESS_RECOMMENDED) {
+		pr_info("Hyper-V: Using MSR ased APIC access\n");

Typo here. "ased" should be "based".

Quoted 63 lines
arch/x86/hyperv/hv_apic.c new file +7 -0
+		apic_set_eoi_write(hv_apic_eoi_write);
+		apic->read      = hv_apic_read;
+		apic->write     = hv_apic_write;
+		apic->icr_write = hv_apic_icr_write;
+		apic->icr_read  = hv_apic_icr_read;
+	}
+}
arch/x86/hyperv/hv_init.c +4 -1
index cfecc2272f2d..71e50fc2b7ef 100644
@@ -242,8 +242,9 @@ static int hv_cpu_die(unsigned int cpu)
  *
  * 1. Setup the hypercall page.
  * 2. Register Hyper-V specific clocksource.
+ * 3. Setup Hyper-V specific APIC entry points.
  */
-void hyperv_init(void)
+void __init hyperv_init(void)
 {
 	u64 guest_id, required_msrs;
 	union hv_x64_msr_hypercall_contents hypercall_msr;
@@ -298,6 +299,8 @@ void hyperv_init(void)
 
 	hyper_alloc_mmu();
 
+	hv_apic_init();
+
 	/*
 	 * Register Hyper-V specific clocksource.
 	 */
arch/x86/include/asm/mshyperv.h +4 -3
index b90e79610cf7..bcced50037c1 100644
@@ -258,7 +258,7 @@ static inline int hv_cpu_number_to_vp_number(int cpu_number)
 	return hv_vp_index[cpu_number];
 }
 
-void hyperv_init(void);
+void __init hyperv_init(void);
 void hyperv_setup_mmu_ops(void);
 void hyper_alloc_mmu(void);
 void hyperv_report_panic(struct pt_regs *regs, long err);
@@ -269,14 +269,16 @@ void hyperv_reenlightenment_intr(struct pt_regs *regs);
 void set_hv_tscchange_cb(void (*cb)(void));
 void clear_hv_tscchange_cb(void);
 void hyperv_stop_tsc_emulation(void);
+void hv_apic_init(void);
 #else /* CONFIG_HYPERV */
-static inline void hyperv_init(void) {}
+static __init  inline void hyperv_init(void) {}
 static inline bool hv_is_hyperv_initialized(void) { return false; }
 static inline void hyperv_cleanup(void) {}
 static inline void hyperv_setup_mmu_ops(void) {}
 static inline void set_hv_tscchange_cb(void (*cb)(void)) {}
 static inline void clear_hv_tscchange_cb(void) {}
 static inline void hyperv_stop_tsc_emulation(void) {};
+static inline void hv_apic_init(void) {}
 static inline struct hv_vp_assist_page *hv_get_vp_assist_page(unsigned int cpu)
 {
 	return NULL;
--
Quoted 1 line

2.15.1

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#26 lore raw

RE: [PATCH 1/5] X86: Hyper-V: Enlighten APIC access

Michael,

Quoted 9 lines · Michael Kelley (EOSG)
Quoted 9 lines

-----Original Message-----
From: [email protected] <[email protected]>
Sent: Wednesday, April 25, 2018 11:13 AM
To: [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; Stephen Hemminger <[email protected]>; Michael Kelley (EOSG) <[email protected]>; [email protected]
Cc: KY Srinivasan <[email protected]>
Subject: [PATCH 1/5] X86: Hyper-V: Enlighten APIC access

Please fix your MUA not to pointlessly copy the whole mail header.

Quoted 6 lines

arch/x86/hyperv/hv_apic.c line 91

Quoted 4 lines
arch/x86/hyperv/hv_apic.c new file +4 -0
+void __init hv_apic_init(void)
+{
+	if (ms_hyperv.hints & HV_X64_APIC_ACCESS_RECOMMENDED) {
+		pr_info("Hyper-V: Using MSR ased APIC access\n");

Typo here. "ased" should be "based".

And please trim the reply to the relevant point. It's annoying to find that single line of review comment in the useless pile of quoted patch.

Thanks,

tglx

#27 lore raw

Re: [PATCH 1/5] X86: Hyper-V: Enlighten APIC access

In reply to [email protected]
I love your patch! Yet something to improve:

Hi Srinivasan,

I love your patch! Yet something to improve:

[auto build test ERROR on v4.17-rc2]
[also build test ERROR on next-20180426]
[cannot apply to tip/x86/core]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url: https://github.com/0day-ci/linux/commits/kys-linuxonhyperv-com/X86-Hyper-V-APIC-enlightenments/20180427-114416
config: i386-randconfig-b0-04270034 (attached as .config)
compiler: gcc-4.9 (Debian 4.9.4-2) 4.9.4 reproduce:

        # save the attached .config to linux build tree
        make ARCH=i386 

All errors (new ones prefixed by >>):

arch/x86/hyperv/hv_apic.c: In function 'hv_apic_read':

>> arch/x86/hyperv/hv_apic.c:65:3: error: implicit declaration of function 'native_apic_mem_read' [-Werror=implicit-function-declaration]
      return native_apic_mem_read(reg);
      ^
   arch/x86/hyperv/hv_apic.c: In function 'hv_apic_write':
>> arch/x86/hyperv/hv_apic.c:79:3: error: implicit declaration of function 'native_apic_mem_write' [-Werror=implicit-function-declaration]
      native_apic_mem_write(reg, val);
      ^
   arch/x86/hyperv/hv_apic.c: In function 'hv_apic_init':
>> arch/x86/hyperv/hv_apic.c:92:3: error: implicit declaration of function 'apic_set_eoi_write' [-Werror=implicit-function-declaration]
      apic_set_eoi_write(hv_apic_eoi_write);
      ^
>> arch/x86/hyperv/hv_apic.c:93:3: error: 'apic' undeclared (first use in this function)
      apic->read      = hv_apic_read;
      ^

arch/x86/hyperv/hv_apic.c:93:3: note: each undeclared identifier is reported only once for each function it appears in
cc1: some warnings being treated as errors

vim +/native_apic_mem_read +65 arch/x86/hyperv/hv_apic.c

    51	
    52	static u32 hv_apic_read(u32 reg)
    53	{
    54		u32 reg_val, hi;
    55	
    56		switch (reg) {
    57		case APIC_EOI:
    58			rdmsr(HV_X64_MSR_EOI, reg_val, hi);
    59			return reg_val;
    60		case APIC_TASKPRI:
    61			rdmsr(HV_X64_MSR_TPR, reg_val, hi);
    62			return reg_val;
    63	
    64		default:
  > 65			return native_apic_mem_read(reg);
    66		}
    67	}
    68	
    69	static void hv_apic_write(u32 reg, u32 val)
    70	{
    71		switch (reg) {
    72		case APIC_EOI:
    73			wrmsr(HV_X64_MSR_EOI, val, 0);
    74			break;
    75		case APIC_TASKPRI:
    76			wrmsr(HV_X64_MSR_TPR, val, 0);
    77			break;
    78		default:
  > 79			native_apic_mem_write(reg, val);
    80		}
    81	}
    82	
    83	static void hv_apic_eoi_write(u32 reg, u32 val)
    84	{
    85		wrmsr(HV_X64_MSR_EOI, val, 0);
    86	}
    87	
    88	void __init hv_apic_init(void)
    89	{
    90		if (ms_hyperv.hints & HV_X64_APIC_ACCESS_RECOMMENDED) {
    91			pr_info("Hyper-V: Using MSR ased APIC access\n");
  > 92			apic_set_eoi_write(hv_apic_eoi_write);
  > 93			apic->read      = hv_apic_read;

---
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