Hardware task switching support

RFC PATCH In review Izik Eidus 2 participants 2 messages Mar 13, 2008 – Mar 16, 2008

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Izik Eidus

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2008-03-13 00:43 UTC #0 lore raw

RFC PATCH 2/2 Hardware task switching support

Quoted 1 line

From 6a7207a0f3ee8af6ebafcec9d40a75b87f00a129 Mon Sep 17 00:00:00 2001

From: Izik Eidus <[email protected]>
Date: Thu, 13 Mar 2008 02:34:21 +0200
Subject: [PATCH] KVM: hardware task switching support

Signed-off-by Izik Eidus <[email protected]>

---
 arch/x86/kvm/svm.c         |   11 +-
 arch/x86/kvm/tss_segment.h |   59 +++++++
 arch/x86/kvm/vmx.c         |   15 ++
 arch/x86/kvm/x86.c         |  385 ++++++++++++++++++++++++++++++++++++++++++++
 include/asm-x86/kvm_host.h |    2 +
 5 files changed, 469 insertions(+), 3 deletions(-)
 create mode 100644 arch/x86/kvm/tss_segment.h

arch/x86/kvm/svm.c +8 -3

index 4e1dd61..be78278 100644
@@ -1121,9 +1121,14 @@ static int invalid_op_interception(struct vcpu_svm *svm,
 static int task_switch_interception(struct vcpu_svm *svm,
 				    struct kvm_run *kvm_run)
 {
-	pr_unimpl(&svm->vcpu, "%s: task switch is unsupported\n", __func__);
-	kvm_run->exit_reason = KVM_EXIT_UNKNOWN;
-	return 0;
+	u16 tss_selector;
+
+	tss_selector = (u16)svm->vmcb->control.exit_info_1;
+	if(svm->vmcb->control.exit_info_2 & ((unsigned long)1 << 36))
+		return kvm_task_switch(&svm->vcpu, tss_selector, 1);
+	if(svm->vmcb->control.exit_info_2 & ((unsigned long)1 << 38))
+		return kvm_task_switch(&svm->vcpu, tss_selector, 2);
+	return kvm_task_switch(&svm->vcpu, tss_selector, 0);
 }
 
 static int cpuid_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run)

arch/x86/kvm/tss_segment.h new file +59 -0

59 lines not on this page · raw message

arch/x86/kvm/vmx.c +15 -0

index 459b0bd..e5fe09b 100644
@@ -2246,6 +2246,20 @@ static int handle_apic_access(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 	return 1;
 }
 
+static int handle_task_switch(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
+{
+	unsigned long exit_qualification;
+	u16 tss_selector;
+	int reason;
+	
+	exit_qualification = vmcs_readl(EXIT_QUALIFICATION);
+
+	reason = (u32)exit_qualification >> 30;
+	tss_selector = (u16)exit_qualification;
+
+	return kvm_task_switch(vcpu, tss_selector, reason);
+}
+
 /*
  * The exit handlers return 1 if the exit was handled fully and guest execution
  * may resume.  Otherwise they set the kvm_run parameter to indicate what needs

@@ -2268,6 +2282,7 @@ static int (*kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu,
 	[EXIT_REASON_TPR_BELOW_THRESHOLD]     = handle_tpr_below_threshold,
 	[EXIT_REASON_APIC_ACCESS]             = handle_apic_access,
 	[EXIT_REASON_WBINVD]                  = handle_wbinvd,
+	[EXIT_REASON_TASK_SWITCH]             = handle_task_switch,
 };
 
 static const int kvm_vmx_max_exit_handlers =

arch/x86/kvm/x86.c +385 -0

397 lines not on this page · raw message

include/asm-x86/kvm_host.h +2 -0

index d9806e2..7ca0462 100644
@@ -472,6 +472,8 @@ int emulator_get_dr(struct x86_emulate_ctxt *ctxt, int dr,
 int emulator_set_dr(struct x86_emulate_ctxt *ctxt, int dr,
 		    unsigned long value);
 
+int kvm_task_switch(struct kvm_vcpu *vcpu, u16 tss_selector, int reason);
+
 void kvm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0);
 void kvm_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr0);
 void kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr0);

Signature · 6 lines

1.5.3.6

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Avi Kivity

2008-03-16 14:18 UTC #1 lore raw

Quoted 25 lines · Izik Eidus

Quoted 1 line

From 6a7207a0f3ee8af6ebafcec9d40a75b87f00a129 Mon Sep 17 00:00:00 2001

From: Izik Eidus <[email protected]>
Date: Thu, 13 Mar 2008 02:34:21 +0200
Subject: [PATCH] KVM: hardware task switching support

Signed-off-by Izik Eidus <[email protected]>

---
 arch/x86/kvm/svm.c         |   11 +-
 arch/x86/kvm/tss_segment.h |   59 +++++++
 arch/x86/kvm/vmx.c         |   15 ++
 arch/x86/kvm/x86.c         |  385 ++++++++++++++++++++++++++++++++++++++++++++
 include/asm-x86/kvm_host.h |    2 +
 5 files changed, 469 insertions(+), 3 deletions(-)
 create mode 100644 arch/x86/kvm/tss_segment.h

arch/x86/kvm/svm.c +0 -2

index 4e1dd61..be78278 100644
@@ -1121,9 +1121,14 @@ static int invalid_op_interception(struct vcpu_svm *svm,
 static int task_switch_interception(struct vcpu_svm *svm,
 				    struct kvm_run *kvm_run)
 {
-	pr_unimpl(&svm->vcpu, "%s: task switch is unsupported\n", __func__);
-	kvm_run->exit_reason = KVM_EXIT_UNKNOWN;

arch/x86/kvm/svm.c static int invalid_op_interception(struct vcpu_svm *svm, · line 1132

Quoted 10 lines

arch/x86/kvm/svm.c +8 -1

-	return 0;
+	u16 tss_selector;
+
+	tss_selector = (u16)svm->vmcb->control.exit_info_1;
+	if(svm->vmcb->control.exit_info_2 & ((unsigned long)1 << 36))
+		return kvm_task_switch(&svm->vcpu, tss_selector, 1);
+	if(svm->vmcb->control.exit_info_2 & ((unsigned long)1 << 38))
+		return kvm_task_switch(&svm->vcpu, tss_selector, 2);
+	return kvm_task_switch(&svm->vcpu, tss_selector, 0);

space after if. Change the magic numbers (36, 38, 0, 1, 2) inuo constants in svm.h and kvm_host.h. (unsigned long)1 << 36 will break on i386 (needs 1ULL << 36).

arch/x86/kvm/tss_segment.h

Quoted 9 lines

arch/x86/kvm/svm.c +0 -0
 }
 
static int cpuid_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run)
arch/x86/kvm/tss_segment.h new file +0 -0
new file mode 100644
index 0000000..622aa10

"tss" already has "segment" in it. call it just tss.h.

Quoted 5 lines

arch/x86/kvm/tss_segment.h new file +4 -0

+
+/* allowed just for 8 bytes segments */
+static int load_guest_segment_descriptor(struct kvm_vcpu *vcpu, u16 selector,
+			      struct desc_struct *seg_desc)

arch/x86/kvm/tss_segment.h

Quoted 10 lines

arch/x86/kvm/tss_segment.h new file +10 -0

+{
+	struct descriptor_table gdt_ldt;
+	u16 index = selector >> 3;
+
+	if (selector & 1 << 2)
+		kvm_x86_ops->get_ldt(vcpu, &gdt_ldt);
+	else
+		kvm_x86_ops->get_gdt(vcpu, &gdt_ldt);
+	if (gdt_ldt.limit < index * 8 + 7)
+		return 1;

This part can be in a helper function shared with load_ and save_guest_segment_descriptor. Maybe rename to read_ and write_ to avoid confusion.

arch/x86/kvm/tss_segment.h

Quoted 11 lines

arch/x86/kvm/tss_segment.h new file +10 -0

+
+static int load_tss_segment32(struct kvm_vcpu *vcpu,
+			      struct desc_struct *seg_desc,
+			      struct tss_segment_32 *tss)
+{
+	u32 base_addr;
+
+	base_addr = seg_desc->base0;
+	base_addr |= (seg_desc->base1 << 16);
+	base_addr |= (seg_desc->base2 << 24);

A helper, again.

Quoted 10 lines

arch/x86/kvm/tss_segment.h new file +9 -0

+static void save_state_to_tss32(struct kvm_vcpu *vcpu,
+				struct tss_segment_32 *tss)
+{
+	struct kvm_segment kvm_seg;
+
+	tss->cr3 = vcpu->arch.cr3;
+	tss->eip = vcpu->arch.rip;
+	tss->eflags = kvm_x86_ops->get_rflags(vcpu);
+	tss->eax = vcpu->arch.regs[VCPU_REGS_RAX];

arch/x86/kvm/tss_segment.h

Quoted 10 lines

arch/x86/kvm/tss_segment.h new file +10 -0

+	tss->ecx = vcpu->arch.regs[VCPU_REGS_RCX];
+	tss->edx = vcpu->arch.regs[VCPU_REGS_RDX];
+	tss->ebx = vcpu->arch.regs[VCPU_REGS_RBX];
+	tss->esp = vcpu->arch.regs[VCPU_REGS_RSP];
+	tss->ebp = vcpu->arch.regs[VCPU_REGS_RBP];
+	tss->esi = vcpu->arch.regs[VCPU_REGS_RSI];
+	tss->edi = vcpu->arch.regs[VCPU_REGS_RDI];
+	
+	get_segment(vcpu, &kvm_seg, VCPU_SREG_ES);
+	tss->es = kvm_seg.selector;

tss->es = get_segment_selector(vcpu, VCPU_SREG_ES);

arch/x86/kvm/tss_segment.h

Quoted 13 lines

arch/x86/kvm/tss_segment.h new file +12 -0

+	load_guest_segment_descriptor(vcpu, tss->ldt_selector,
+				      &seg_desc);
+	seg_desct_to_kvm_desct(&seg_desc, tss->ldt_selector,
+			       &kvm_seg);
+	set_segment(vcpu, &kvm_seg, VCPU_SREG_LDTR);
+
+	load_guest_segment_descriptor(vcpu, tss->es, &seg_desc);
+	seg_desct_to_kvm_desct(&seg_desc, tss->es, &kvm_seg);
+	kvm_seg.type |= 1;
+	if (!kvm_seg.s)
+		kvm_seg.unusable = 1;
+	set_segment(vcpu, &kvm_seg, VCPU_SREG_ES);

Wrap these into a helper.

Signature · 7 lines

error compiling committee.c: too many arguments to function


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