From 799a4190e7341b9bb24549245f2b8f7d11c65360 Mon Sep 17 00:00:00 2001 From: Ben Gardon Date: Wed, 14 Oct 2020 20:26:41 +0200 Subject: [PATCH] kvm: x86/mmu: Separate making SPTEs from set_spte Separate the functions for generating leaf page table entries from the function that inserts them into the paging structure. This refactoring will facilitate changes to the MMU sychronization model to use atomic compare / exchanges (which are not guaranteed to succeed) instead of a monolithic MMU lock. No functional change expected. Tested by running kvm-unit-tests and KVM selftests on an Intel Haswell machine. This commit introduced no new failures. This series can be viewed in Gerrit at: https://linux-review.googlesource.com/c/virt/kvm/kvm/+/2538 Signed-off-by: Ben Gardon Reviewed-by: Peter Shier Signed-off-by: Paolo Bonzini --- arch/x86/kvm/mmu/mmu.c | 49 ++++++++++++++++++++++++++++-------------- 1 file changed, 33 insertions(+), 16 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 60103fd07bd2..ef4a63af8fce 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -2996,20 +2996,15 @@ static bool kvm_is_mmio_pfn(kvm_pfn_t pfn) #define SET_SPTE_NEED_REMOTE_TLB_FLUSH BIT(1) #define SET_SPTE_SPURIOUS BIT(2) -static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep, - unsigned int pte_access, int level, - gfn_t gfn, kvm_pfn_t pfn, bool speculative, - bool can_unsync, bool host_writable) +static int make_spte(struct kvm_vcpu *vcpu, unsigned int pte_access, int level, + gfn_t gfn, kvm_pfn_t pfn, u64 old_spte, bool speculative, + bool can_unsync, bool host_writable, bool ad_disabled, + u64 *new_spte) { u64 spte = 0; int ret = 0; - struct kvm_mmu_page *sp; - if (set_mmio_spte(vcpu, sptep, gfn, pfn, pte_access)) - return 0; - - sp = sptep_to_sp(sptep); - if (sp_ad_disabled(sp)) + if (ad_disabled) spte |= SPTE_AD_DISABLED_MASK; else if (kvm_vcpu_ad_need_write_protect(vcpu)) spte |= SPTE_AD_WRPROT_ONLY_MASK; @@ -3062,8 +3057,8 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep, * is responsibility of mmu_get_page / kvm_sync_page. * Same reasoning can be applied to dirty page accounting. */ - if (!can_unsync && is_writable_pte(*sptep)) - goto set_pte; + if (!can_unsync && is_writable_pte(old_spte)) + goto out; if (mmu_need_write_protect(vcpu, gfn, can_unsync)) { pgprintk("%s: found shadow page for %llx, marking ro\n", @@ -3074,15 +3069,37 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep, } } - if (pte_access & ACC_WRITE_MASK) { - kvm_vcpu_mark_page_dirty(vcpu, gfn); + if (pte_access & ACC_WRITE_MASK) spte |= spte_shadow_dirty_mask(spte); - } if (speculative) spte = mark_spte_for_access_track(spte); -set_pte: +out: + *new_spte = spte; + return ret; +} + +static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep, + unsigned int pte_access, int level, + gfn_t gfn, kvm_pfn_t pfn, bool speculative, + bool can_unsync, bool host_writable) +{ + u64 spte; + struct kvm_mmu_page *sp; + int ret; + + if (set_mmio_spte(vcpu, sptep, gfn, pfn, pte_access)) + return 0; + + sp = sptep_to_sp(sptep); + + ret = make_spte(vcpu, pte_access, level, gfn, pfn, *sptep, speculative, + can_unsync, host_writable, sp_ad_disabled(sp), &spte); + + if (spte & PT_WRITABLE_MASK) + kvm_vcpu_mark_page_dirty(vcpu, gfn); + if (*sptep == spte) ret |= SET_SPTE_SPURIOUS; else if (mmu_spte_update(sptep, spte))