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KVM: limit the number of pages per memory slot

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This patch limits the number of pages per memory slot to make
us free from extra care about type issues.

Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Takuya Yoshikawa 2010-04-13 22:47:24 +09:00 committed by Avi Kivity
parent 020df0794f
commit 660c22c425
2 changed files with 12 additions and 5 deletions
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6
include/linux/kvm_host.h
View File

@ -105,6 +105,12 @@ struct kvm_vcpu {
struct kvm_vcpu_arch arch; struct kvm_vcpu_arch arch;
}; };
/*
* Some of the bitops functions do not support too long bitmaps.
* This number must be determined not to exceed such limits.
*/
#define KVM_MEM_MAX_NR_PAGES ((1UL << 31) - 1)
struct kvm_memory_slot { struct kvm_memory_slot {
gfn_t base_gfn; gfn_t base_gfn;
unsigned long npages; unsigned long npages;

11
virt/kvm/kvm_main.c
View File

@ -557,6 +557,10 @@ int __kvm_set_memory_region(struct kvm *kvm,
base_gfn = mem->guest_phys_addr >> PAGE_SHIFT; base_gfn = mem->guest_phys_addr >> PAGE_SHIFT;
npages = mem->memory_size >> PAGE_SHIFT; npages = mem->memory_size >> PAGE_SHIFT;
r = -EINVAL;
if (npages > KVM_MEM_MAX_NR_PAGES)
goto out;
if (!npages) if (!npages)
mem->flags &= ~KVM_MEM_LOG_DIRTY_PAGES; mem->flags &= ~KVM_MEM_LOG_DIRTY_PAGES;
@ -1187,13 +1191,10 @@ void mark_page_dirty(struct kvm *kvm, gfn_t gfn)
memslot = gfn_to_memslot_unaliased(kvm, gfn); memslot = gfn_to_memslot_unaliased(kvm, gfn);
if (memslot && memslot->dirty_bitmap) { if (memslot && memslot->dirty_bitmap) {
unsigned long rel_gfn = gfn - memslot->base_gfn; unsigned long rel_gfn = gfn - memslot->base_gfn;
unsigned long *p = memslot->dirty_bitmap +
rel_gfn / BITS_PER_LONG;
int offset = rel_gfn % BITS_PER_LONG;
/* avoid RMW */ /* avoid RMW */
if (!generic_test_le_bit(offset, p)) if (!generic_test_le_bit(rel_gfn, memslot->dirty_bitmap))
generic___set_le_bit(offset, p); generic___set_le_bit(rel_gfn, memslot->dirty_bitmap);
} }
} }