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authorZachary Amsden <zach@vmware.com>2007-04-08 16:04:01 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-04-08 19:47:55 -0700
commit49f19710512c825aaea73b9207b3a848027cda1d (patch)
tree06da31bd9a84273e12aa43f536f90eb8146ff92e /arch
parenta5bfffac645a7b2d8119f8bbae34df5c94832799 (diff)
[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>
Diffstat (limited to 'arch')
-rw-r--r--arch/i386/kernel/vmi.c23
-rw-r--r--arch/i386/mm/highmem.c2
2 files changed, 24 insertions, 1 deletions
diff --git a/arch/i386/kernel/vmi.c b/arch/i386/kernel/vmi.c
index fb07a1aad22..edc339fa503 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 bb2de1089ad..ac70d09df7e 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;
}