From 87bf6e7de1134f48681fd2ce4b7c1ec45458cb6d Mon Sep 17 00:00:00 2001 From: Takuya Yoshikawa Date: Mon, 12 Apr 2010 19:35:35 +0900 Subject: [PATCH] KVM: fix the handling of dirty bitmaps to avoid overflows Int is not long enough to store the size of a dirty bitmap. This patch fixes this problem with the introduction of a wrapper function to calculate the sizes of dirty bitmaps. Note: in mark_page_dirty(), we have to consider the fact that __set_bit() takes the offset as int, not long. Signed-off-by: Takuya Yoshikawa Signed-off-by: Marcelo Tosatti --- arch/ia64/kvm/kvm-ia64.c | 9 +++++---- arch/powerpc/kvm/book3s.c | 5 +++-- arch/x86/kvm/x86.c | 5 +++-- include/linux/kvm_host.h | 5 +++++ virt/kvm/kvm_main.c | 13 ++++++++----- 5 files changed, 24 insertions(+), 13 deletions(-) diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c index 73c5c2b..7f3c0a2 100644 --- a/arch/ia64/kvm/kvm-ia64.c +++ b/arch/ia64/kvm/kvm-ia64.c @@ -1802,7 +1802,8 @@ static int kvm_ia64_sync_dirty_log(struct kvm *kvm, { struct kvm_memory_slot *memslot; int r, i; - long n, base; + long base; + unsigned long n; unsigned long *dirty_bitmap = (unsigned long *)(kvm->arch.vm_base + offsetof(struct kvm_vm_data, kvm_mem_dirty_log)); @@ -1815,7 +1816,7 @@ static int kvm_ia64_sync_dirty_log(struct kvm *kvm, if (!memslot->dirty_bitmap) goto out; - n = ALIGN(memslot->npages, BITS_PER_LONG) / 8; + n = kvm_dirty_bitmap_bytes(memslot); base = memslot->base_gfn / BITS_PER_LONG; for (i = 0; i < n/sizeof(long); ++i) { @@ -1831,7 +1832,7 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log) { int r; - int n; + unsigned long n; struct kvm_memory_slot *memslot; int is_dirty = 0; @@ -1850,7 +1851,7 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, if (is_dirty) { kvm_flush_remote_tlbs(kvm); memslot = &kvm->memslots->memslots[log->slot]; - n = ALIGN(memslot->npages, BITS_PER_LONG) / 8; + n = kvm_dirty_bitmap_bytes(memslot); memset(memslot->dirty_bitmap, 0, n); } r = 0; diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c index 25da07f..604af29 100644 --- a/arch/powerpc/kvm/book3s.c +++ b/arch/powerpc/kvm/book3s.c @@ -1004,7 +1004,8 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_vcpu *vcpu; ulong ga, ga_end; int is_dirty = 0; - int r, n; + int r; + unsigned long n; mutex_lock(&kvm->slots_lock); @@ -1022,7 +1023,7 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, kvm_for_each_vcpu(n, vcpu, kvm) kvmppc_mmu_pte_pflush(vcpu, ga, ga_end); - n = ALIGN(memslot->npages, BITS_PER_LONG) / 8; + n = kvm_dirty_bitmap_bytes(memslot); memset(memslot->dirty_bitmap, 0, n); } diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 9ad3d06..45aa90f 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2612,8 +2612,9 @@ static int kvm_vm_ioctl_reinject(struct kvm *kvm, int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log) { - int r, n, i; + int r, i; struct kvm_memory_slot *memslot; + unsigned long n; unsigned long is_dirty = 0; unsigned long *dirty_bitmap = NULL; @@ -2628,7 +2629,7 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, if (!memslot->dirty_bitmap) goto out; - n = ALIGN(memslot->npages, BITS_PER_LONG) / 8; + n = kvm_dirty_bitmap_bytes(memslot); r = -ENOMEM; dirty_bitmap = vmalloc(n); diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index a3fd0f9..9ad825e 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -119,6 +119,11 @@ struct kvm_memory_slot { int user_alloc; }; +static inline unsigned long kvm_dirty_bitmap_bytes(struct kvm_memory_slot *memslot) +{ + return ALIGN(memslot->npages, BITS_PER_LONG) / 8; +} + struct kvm_kernel_irq_routing_entry { u32 gsi; u32 type; diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 5a0cd19..364daac 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -648,7 +648,7 @@ skip_lpage: /* Allocate page dirty bitmap if needed */ if ((new.flags & KVM_MEM_LOG_DIRTY_PAGES) && !new.dirty_bitmap) { - unsigned dirty_bytes = ALIGN(npages, BITS_PER_LONG) / 8; + unsigned long dirty_bytes = kvm_dirty_bitmap_bytes(&new); new.dirty_bitmap = vmalloc(dirty_bytes); if (!new.dirty_bitmap) @@ -768,7 +768,7 @@ int kvm_get_dirty_log(struct kvm *kvm, { struct kvm_memory_slot *memslot; int r, i; - int n; + unsigned long n; unsigned long any = 0; r = -EINVAL; @@ -780,7 +780,7 @@ int kvm_get_dirty_log(struct kvm *kvm, if (!memslot->dirty_bitmap) goto out; - n = ALIGN(memslot->npages, BITS_PER_LONG) / 8; + n = kvm_dirty_bitmap_bytes(memslot); for (i = 0; !any && i < n/sizeof(long); ++i) any = memslot->dirty_bitmap[i]; @@ -1186,10 +1186,13 @@ void mark_page_dirty(struct kvm *kvm, gfn_t gfn) memslot = gfn_to_memslot_unaliased(kvm, gfn); if (memslot && memslot->dirty_bitmap) { 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 */ - if (!generic_test_le_bit(rel_gfn, memslot->dirty_bitmap)) - generic___set_le_bit(rel_gfn, memslot->dirty_bitmap); + if (!generic_test_le_bit(offset, p)) + generic___set_le_bit(offset, p); } } -- 1.8.2.3