From: Wanpeng Li Date: Wed, 15 Apr 2015 02:24:54 +0000 (+0800) Subject: kvm: mmu: don't do memslot overflow check X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=130005231c9f2090b1b177e2cca9841b562c1784;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git kvm: mmu: don't do memslot overflow check 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 Signed-off-by: Wanpeng Li Message-Id: <1429064694-3072-1-git-send-email-wanpeng.li@linux.intel.com> Signed-off-by: Paolo Bonzini --- diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 146f295ee322..07bb22157338 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -4504,19 +4504,12 @@ 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) @@ -4534,7 +4527,6 @@ void kvm_mmu_zap_collapsible_sptes(struct kvm *kvm, if (flush) kvm_flush_remote_tlbs(kvm); -out: spin_unlock(&kvm->mmu_lock); }