From 6e7d035407dc402a313e466c4f7ccb21aaed0da2 Mon Sep 17 00:00:00 2001 From: Xiao Guangrong Date: Wed, 20 Jun 2012 15:58:33 +0800 Subject: [PATCH] KVM: MMU: fold tlb flush judgement into mmu_spte_update mmu_spte_update() is the common function, we can easily audit the path Signed-off-by: Xiao Guangrong Signed-off-by: Avi Kivity --- arch/x86/kvm/mmu.c | 33 ++++++++++++++++++++------------- 1 file changed, 20 insertions(+), 13 deletions(-) diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index ed9e96806082..a2fc65ba76a5 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -479,15 +479,24 @@ static void mmu_spte_set(u64 *sptep, u64 new_spte) /* Rules for using mmu_spte_update: * Update the state bits, it means the mapped pfn is not changged. + * + * Whenever we overwrite a writable spte with a read-only one we + * should flush remote TLBs. Otherwise rmap_write_protect + * will find a read-only spte, even though the writable spte + * might be cached on a CPU's TLB, the return value indicates this + * case. */ -static void mmu_spte_update(u64 *sptep, u64 new_spte) +static bool mmu_spte_update(u64 *sptep, u64 new_spte) { u64 mask, old_spte = *sptep; + bool ret = false; WARN_ON(!is_rmap_spte(new_spte)); - if (!is_shadow_present_pte(old_spte)) - return mmu_spte_set(sptep, new_spte); + if (!is_shadow_present_pte(old_spte)) { + mmu_spte_set(sptep, new_spte); + return ret; + } new_spte |= old_spte & shadow_dirty_mask; @@ -500,13 +509,18 @@ static void mmu_spte_update(u64 *sptep, u64 new_spte) else old_spte = __update_clear_spte_slow(sptep, new_spte); + if (is_writable_pte(old_spte) && !is_writable_pte(new_spte)) + ret = true; + if (!shadow_accessed_mask) - return; + return ret; if (spte_is_bit_cleared(old_spte, new_spte, shadow_accessed_mask)) kvm_set_pfn_accessed(spte_to_pfn(old_spte)); if (spte_is_bit_cleared(old_spte, new_spte, shadow_dirty_mask)) kvm_set_pfn_dirty(spte_to_pfn(old_spte)); + + return ret; } /* @@ -2268,7 +2282,7 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep, gfn_t gfn, pfn_t pfn, bool speculative, bool can_unsync, bool host_writable) { - u64 spte, entry = *sptep; + u64 spte; int ret = 0; if (set_mmio_spte(sptep, gfn, pfn, pte_access)) @@ -2346,14 +2360,7 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep, mark_page_dirty(vcpu->kvm, gfn); set_pte: - mmu_spte_update(sptep, spte); - /* - * If we overwrite a writable spte with a read-only one we - * should flush remote TLBs. Otherwise rmap_write_protect - * will find a read-only spte, even though the writable spte - * might be cached on a CPU's TLB. - */ - if (is_writable_pte(entry) && !is_writable_pte(*sptep)) + if (mmu_spte_update(sptep, spte)) kvm_flush_remote_tlbs(vcpu->kvm); done: return ret; -- 2.34.1