linux-kernel - Re: [PATCH] Bugfix for VMI paravirt ops

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Date:	Thu, 05 Apr 2007 17:52:17 -0700
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	Zachary Amsden <zach@...are.com>
CC:	Andi Kleen <ak@...e.de>, Andrew Morton <akpm@...l.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...l.org>
Subject: Re: [PATCH] Bugfix for VMI paravirt ops

Zachary Amsden wrote:
> Yes, thought about several solutions, and this seems the best.  But it
> requires a new paravirt-op.

Not with the power of multiplexing.  Something like this, perhaps?

    J

diff -r 5be4a5ff8e6b arch/i386/mm/highmem.c
--- a/arch/i386/mm/highmem.c	Thu Apr 05 17:04:04 2007 -0700
+++ b/arch/i386/mm/highmem.c	Thu Apr 05 17:50:46 2007 -0700
@@ -42,6 +42,8 @@ void *kmap_atomic_prot(struct page *page
 
 	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
 	set_pte(kmap_pte-idx, mk_pte(page, prot));
+
+	arch_flush_lazy_mmu_mode();
 
 	return (void*) vaddr;
 }
diff -r 5be4a5ff8e6b include/asm-generic/pgtable.h
--- a/include/asm-generic/pgtable.h	Thu Apr 05 17:04:04 2007 -0700
+++ b/include/asm-generic/pgtable.h	Thu Apr 05 17:50:46 2007 -0700
@@ -180,6 +180,7 @@ static inline void ptep_set_wrprotect(st
 #ifndef __HAVE_ARCH_ENTER_LAZY_MMU_MODE
 #define arch_enter_lazy_mmu_mode()	do {} while (0)
 #define arch_leave_lazy_mmu_mode()	do {} while (0)
+#define arch_flush_lazy_mmu_mode()	do {} while (0)
 #endif
 
 /*
@@ -193,6 +194,7 @@ static inline void ptep_set_wrprotect(st
 #ifndef __HAVE_ARCH_ENTER_LAZY_CPU_MODE
 #define arch_enter_lazy_cpu_mode()	do {} while (0)
 #define arch_leave_lazy_cpu_mode()	do {} while (0)
+#define arch_flush_lazy_cpu_mode()	do {} while (0)
 #endif
 
 /*
diff -r 5be4a5ff8e6b include/asm-i386/paravirt.h
--- a/include/asm-i386/paravirt.h	Thu Apr 05 17:04:04 2007 -0700
+++ b/include/asm-i386/paravirt.h	Thu Apr 05 17:50:46 2007 -0700
@@ -27,9 +27,10 @@ struct desc_struct;
 
 /* Lazy mode for batching updates / context switch */
 enum paravirt_lazy_mode {
-	PARAVIRT_LAZY_NONE = 0,
-	PARAVIRT_LAZY_MMU = 1,
-	PARAVIRT_LAZY_CPU = 2,
+	PARAVIRT_LAZY_NONE = 0,		/* exit lazy mode */
+	PARAVIRT_LAZY_MMU = 1,		/* lazy mmu updates */
+	PARAVIRT_LAZY_CPU = 2,		/* lazy cpu state updates */
+	PARAVIRT_LAZY_FLUSH = 3,	/* flush pending changes, if any */
 };
 
 struct paravirt_ops
@@ -1044,6 +1045,10 @@ static inline void arch_leave_lazy_cpu_m
 {
 	PVOP_VCALL1(set_lazy_mode, PARAVIRT_LAZY_NONE);
 }
+static inline void arch_flush_lazy_cpu_mode(void)
+{
+	PVOP_VCALL1(set_lazy_mode, PARAVIRT_LAZY_FLUSH);
+}
 
 #define  __HAVE_ARCH_ENTER_LAZY_MMU_MODE
 static inline void arch_enter_lazy_mmu_mode(void)
@@ -1053,6 +1058,10 @@ static inline void arch_leave_lazy_mmu_m
 static inline void arch_leave_lazy_mmu_mode(void)
 {
 	PVOP_VCALL1(set_lazy_mode, PARAVIRT_LAZY_NONE);
+}
+static inline void arch_flush_lazy_mmu_mode(void)
+{
+	PVOP_VCALL1(set_lazy_mode, PARAVIRT_LAZY_FLUSH);
 }
 
 void _paravirt_nop(void);

-
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