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paravirt: clean up lazy mode handling

RFC PATCH In review Jeremy Fitzhardinge 1 participant 1 message Oct 9, 2007

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virtio core PARAVIRT_OPS interface
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Jeremy Fitzhardinge

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RFC PATCH 2/2 paravirt: clean up lazy mode handling

[ I think this is a straight repost this patch, which addresses all the previous comments. I'd like to submit this for .24 as the basis for a unified paravirt_ops. Any objections? ]

Currently, the set_lazy_mode pv_op is overloaded with 5 functions:
1. enter lazy cpu mode
2. leave lazy cpu mode
3. enter lazy mmu mode
4. leave lazy mmu mode
5. flush pending batched operations

This complicates each paravirt backend, since it needs to deal with all the possible state transitions, handling flushing, etc. In particular, flushing is quite distinct from the other 4 functions, and seems to just cause complication.

This patch removes the set_lazy_mode operation, and adds "enter" and "leave" lazy mode operations on mmu_ops and cpu_ops. All the logic associated with enter and leaving lazy states is now in common code (basically BUG_ONs to make sure that no mode is current when entering a lazy mode, and make sure that the mode is current when leaving). Also, flush is handled in a common way, by simply leaving and re-entering the lazy mode.

The result is that the Xen and VMI lazy mode implementations are much simpler; as would lguest's be.

Signed-off-by Jeremy Fitzhardinge <[email protected]>
Cc Andi Kleen <[email protected]>
Cc Zach Amsden <[email protected]>
Cc Rusty Russell <[email protected]>
Cc Avi Kivity <[email protected]>
Cc Anthony Liguory <[email protected]>
Cc "Glauber de Oliveira Costa" <[email protected]>
Cc "Nakajima, Jun" <[email protected]>
---
 arch/i386/kernel/paravirt.c |   58 +++++++++++++++++++++++++++++++++++++++----
 arch/i386/kernel/vmi.c      |   45 +++++++++++++++++++--------------
 arch/i386/xen/enlighten.c   |   44 ++++++++++----------------------
 arch/i386/xen/mmu.c         |    2 -
 arch/i386/xen/multicalls.h  |    2 -
 arch/i386/xen/xen-ops.h     |    7 -----
 include/asm-i386/paravirt.h |   52 ++++++++++++++++++++++++--------------
 7 files changed, 128 insertions(+), 82 deletions(-)

===================================================================

arch/i386/kernel/paravirt.c +53 -5
@@ -265,6 +265,49 @@ int paravirt_disable_iospace(void)
 	}
 
 	return ret;
+}
+
+static DEFINE_PER_CPU(enum paravirt_lazy_mode, paravirt_lazy_mode) = PARAVIRT_LAZY_NONE;
+
+static inline void enter_lazy(enum paravirt_lazy_mode mode)
+{
+	BUG_ON(x86_read_percpu(paravirt_lazy_mode) != PARAVIRT_LAZY_NONE);
+	BUG_ON(preemptible());
+
+	x86_write_percpu(paravirt_lazy_mode, mode);
+}
+
+void paravirt_leave_lazy(enum paravirt_lazy_mode mode)
+{
+	BUG_ON(x86_read_percpu(paravirt_lazy_mode) != mode);
+	BUG_ON(preemptible());
+
+	x86_write_percpu(paravirt_lazy_mode, PARAVIRT_LAZY_NONE);
+}
+
+void paravirt_enter_lazy_mmu(void)
+{
+	enter_lazy(PARAVIRT_LAZY_MMU);
+}
+
+void paravirt_leave_lazy_mmu(void)
+{
+	paravirt_leave_lazy(PARAVIRT_LAZY_MMU);
+}
+
+void paravirt_enter_lazy_cpu(void)
+{
+	enter_lazy(PARAVIRT_LAZY_CPU);
+}
+
+void paravirt_leave_lazy_cpu(void)
+{
+	paravirt_leave_lazy(PARAVIRT_LAZY_CPU);
+}
+
+enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
+{
+	return x86_read_percpu(paravirt_lazy_mode);
 }
 
 struct paravirt_ops paravirt_ops = {

@@ -333,6 +376,11 @@ struct paravirt_ops paravirt_ops = {
 
 		 .set_iopl_mask = native_set_iopl_mask,
 		 .io_delay = native_io_delay,
+
+		 .lazy_mode = {
+			 .enter = paravirt_nop,
+			 .leave = paravirt_nop,
+		 },
 	 },
 
 	.pv_apic_ops = {

@@ -346,10 +394,6 @@ struct paravirt_ops paravirt_ops = {
 #endif
 	 },
 
-	.pv_misc_ops = {
-		 .set_lazy_mode = paravirt_nop,
-	 },
-
 	.pv_mmu_ops = {
 		 .pagetable_setup_start = native_pagetable_setup_start,
 		 .pagetable_setup_done = native_pagetable_setup_done,

@@ -400,6 +444,11 @@ struct paravirt_ops paravirt_ops = {
 		 .dup_mmap = paravirt_nop,
 		 .exit_mmap = paravirt_nop,
 		 .activate_mm = paravirt_nop,
+
+		 .lazy_mode = {
+			 .enter = paravirt_nop,
+			 .leave = paravirt_nop,
+		 },
 	 },
 };
 

@@ -417,7 +466,6 @@ static void __init __used pv_aliases(voi
 
 	substructure(pv_info);
 	substructure(pv_init_ops);
-	substructure(pv_misc_ops);
 	substructure(pv_time_ops);
 	substructure(pv_cpu_ops);
 	substructure(pv_irq_ops);

===================================================================

arch/i386/kernel/vmi.c +26 -19

57 lines not on this page · raw message

===================================================================

arch/i386/xen/enlighten.c +14 -30

81 lines not on this page · raw message

===================================================================

arch/i386/xen/mmu.c +1 -1
@@ -154,7 +154,7 @@ void xen_set_pte_at(struct mm_struct *mm
 		    pte_t *ptep, pte_t pteval)
 {
 	if (mm == current->mm || mm == &init_mm) {
-		if (xen_get_lazy_mode() == PARAVIRT_LAZY_MMU) {
+		if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) {
 			struct multicall_space mcs;
 			mcs = xen_mc_entry(0);

===================================================================

arch/i386/xen/multicalls.h +1 -1
@@ -35,7 +35,7 @@ void xen_mc_flush(void);
 /* Issue a multicall if we're not in a lazy mode */
 static inline void xen_mc_issue(unsigned mode)
 {
-	if ((xen_get_lazy_mode() & mode) == 0)
+	if ((paravirt_get_lazy_mode() & mode) == 0)
 		xen_mc_flush();
 
 	/* restore flags saved in xen_mc_batch */

===================================================================

arch/i386/xen/xen-ops.h +0 -7
@@ -31,13 +31,6 @@ bool xen_vcpu_stolen(int vcpu);
 
 void xen_mark_init_mm_pinned(void);
 
-DECLARE_PER_CPU(enum paravirt_lazy_mode, xen_lazy_mode);
-
-static inline unsigned xen_get_lazy_mode(void)
-{
-	return x86_read_percpu(xen_lazy_mode);
-}
-
 void __init xen_fill_possible_map(void);
 
 void __init xen_setup_vcpu_info_placement(void);

===================================================================

include/asm-i386/paravirt.h +33 -19

120 lines not on this page · raw message