From 49f19710512c825aaea73b9207b3a848027cda1d Mon Sep 17 00:00:00 2001
From: Zachary Amsden <zach@vmware.com>
Date: Sun, 8 Apr 2007 16:04:01 -0700
Subject: [PATCH] [PATCH] Proper fix for highmem kmap_atomic functions for VMI
for 2.6.21
Since lazy MMU batching mode still allows interrupts to enter, it is
possible for interrupt handlers to try to use kmap_atomic, which fails when
lazy mode is active, since the PTE update to highmem will be delayed. The
best workaround is to issue an explicit flush in kmap_atomic_functions
case; this is the only way nested PTE updates can happen in the interrupt
handler.
Thanks to Jeremy Fitzhardinge for noting the bug and suggestions on a fix.
This patch gets reverted again when we start 2.6.22 and the bug gets fixed
differently.
Signed-off-by: Zachary Amsden <zach@vmware.com>
Cc: Andi Kleen <ak@muc.de>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
arch/i386/kernel/vmi.c | 23 ++++++++++++++++++++++-
arch/i386/mm/highmem.c | 2 ++
include/asm-generic/pgtable.h | 2 ++
include/asm-i386/paravirt.h | 3 +++
4 files changed, 29 insertions(+), 1 deletion(-)
diff --git a/arch/i386/kernel/vmi.c b/arch/i386/kernel/vmi.c
index fb07a1aad2250..edc339fa50382 100644
--- a/arch/i386/kernel/vmi.c
+++ b/arch/i386/kernel/vmi.c
@@ -69,6 +69,7 @@ struct {
void (*flush_tlb)(int);
void (*set_initial_ap_state)(int, int);
void (*halt)(void);
+ void (*set_lazy_mode)(int mode);
} vmi_ops;
/* XXX move this to alternative.h */
@@ -574,6 +575,26 @@ vmi_startup_ipi_hook(int phys_apicid, unsigned long start_eip,
}
#endif
+static void vmi_set_lazy_mode(int mode)
+{
+ static DEFINE_PER_CPU(int, lazy_mode);
+
+ if (!vmi_ops.set_lazy_mode)
+ return;
+
+ /* Modes should never nest or overlap */
+ BUG_ON(__get_cpu_var(lazy_mode) && !(mode == PARAVIRT_LAZY_NONE ||
+ mode == PARAVIRT_LAZY_FLUSH));
+
+ if (mode == PARAVIRT_LAZY_FLUSH) {
+ vmi_ops.set_lazy_mode(0);
+ vmi_ops.set_lazy_mode(__get_cpu_var(lazy_mode));
+ } else {
+ vmi_ops.set_lazy_mode(mode);
+ __get_cpu_var(lazy_mode) = mode;
+ }
+}
+
static inline int __init check_vmi_rom(struct vrom_header *rom)
{
struct pci_header *pci;
@@ -804,7 +825,7 @@ static inline int __init activate_vmi(void)
para_wrap(load_esp0, vmi_load_esp0, set_kernel_stack, UpdateKernelStack);
para_fill(set_iopl_mask, SetIOPLMask);
para_fill(io_delay, IODelay);
- para_fill(set_lazy_mode, SetLazyMode);
+ para_wrap(set_lazy_mode, vmi_set_lazy_mode, set_lazy_mode, SetLazyMode);
/* user and kernel flush are just handled with different flags to FlushTLB */
para_wrap(flush_tlb_user, vmi_flush_tlb_user, flush_tlb, FlushTLB);
diff --git a/arch/i386/mm/highmem.c b/arch/i386/mm/highmem.c
index bb2de1089add4..ac70d09df7ee5 100644
--- a/arch/i386/mm/highmem.c
+++ b/arch/i386/mm/highmem.c
@@ -42,6 +42,7 @@ void *kmap_atomic(struct page *page, enum km_type type)
vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
set_pte(kmap_pte-idx, mk_pte(page, kmap_prot));
+ arch_flush_lazy_mmu_mode();
return (void*) vaddr;
}
@@ -82,6 +83,7 @@ void *kmap_atomic_pfn(unsigned long pfn, enum km_type type)
idx = type + KM_TYPE_NR*smp_processor_id();
vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
set_pte(kmap_pte-idx, pfn_pte(pfn, kmap_prot));
+ arch_flush_lazy_mmu_mode();
return (void*) vaddr;
}
diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index 00c23433b39f2..6d7e279b14900 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -180,6 +180,7 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addres
#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(struct mm_struct *mm, unsigned long addres
#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 --git a/include/asm-i386/paravirt.h b/include/asm-i386/paravirt.h
index 46dc34ca887a8..e63f1e444fcf1 100644
--- a/include/asm-i386/paravirt.h
+++ b/include/asm-i386/paravirt.h
@@ -421,14 +421,17 @@ static inline void pmd_clear(pmd_t *pmdp)
#define PARAVIRT_LAZY_NONE 0
#define PARAVIRT_LAZY_MMU 1
#define PARAVIRT_LAZY_CPU 2
+#define PARAVIRT_LAZY_FLUSH 3
#define __HAVE_ARCH_ENTER_LAZY_CPU_MODE
#define arch_enter_lazy_cpu_mode() paravirt_ops.set_lazy_mode(PARAVIRT_LAZY_CPU)
#define arch_leave_lazy_cpu_mode() paravirt_ops.set_lazy_mode(PARAVIRT_LAZY_NONE)
+#define arch_flush_lazy_cpu_mode() paravirt_ops.set_lazy_mode(PARAVIRT_LAZY_FLUSH)
#define __HAVE_ARCH_ENTER_LAZY_MMU_MODE
#define arch_enter_lazy_mmu_mode() paravirt_ops.set_lazy_mode(PARAVIRT_LAZY_MMU)
#define arch_leave_lazy_mmu_mode() paravirt_ops.set_lazy_mode(PARAVIRT_LAZY_NONE)
+#define arch_flush_lazy_mmu_mode() paravirt_ops.set_lazy_mode(PARAVIRT_LAZY_FLUSH)
/* These all sit in the .parainstructions section to tell us what to patch. */
struct paravirt_patch {
--
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