Messages in this thread Patch in this message | | | From | Wanpeng Li <> | Subject | [PATCH v2] kvm: mmu: don't do memslot overflow check | Date | Wed, 15 Apr 2015 10:24:54 +0800 |
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As Andres pointed out:
| I don't understand the value of this check here. Are we looking for a | broken memslot? Shouldn't this be a BUG_ON? Is this the place to care | about these things? npages is capped to KVM_MEM_MAX_NR_PAGES, i.e. | 2^31. A 64 bit overflow would be caused by a gigantic gfn_start which | would be trouble in many other ways.
This patch drops the memslot overflow check to make the codes more simple.
Reviewed-by: Andres Lagar-Cavilla <andreslc@google.com> Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com> --- v1 -> v2: * Fix Andres's name * Add Andres's Reviewed-by
arch/x86/kvm/mmu.c | 12 ++---------- 1 file changed, 2 insertions(+), 10 deletions(-)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 2a0d77e..9265fda 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -4505,19 +4505,12 @@ void kvm_mmu_zap_collapsible_sptes(struct kvm *kvm, bool flush = false; unsigned long *rmapp; unsigned long last_index, index; - gfn_t gfn_start, gfn_end; spin_lock(&kvm->mmu_lock); - gfn_start = memslot->base_gfn; - gfn_end = memslot->base_gfn + memslot->npages - 1; - - if (gfn_start >= gfn_end) - goto out; - rmapp = memslot->arch.rmap[0]; - last_index = gfn_to_index(gfn_end, memslot->base_gfn, - PT_PAGE_TABLE_LEVEL); + last_index = gfn_to_index(memslot->base_gfn + memslot->npages - 1, + memslot->base_gfn, PT_PAGE_TABLE_LEVEL); for (index = 0; index <= last_index; ++index, ++rmapp) { if (*rmapp) @@ -4535,7 +4528,6 @@ void kvm_mmu_zap_collapsible_sptes(struct kvm *kvm, if (flush) kvm_flush_remote_tlbs(kvm); -out: spin_unlock(&kvm->mmu_lock); } -- 1.9.1
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