From d8fa2031faaba3332d9bc44671a14125f49823dd Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Mon, 22 Jan 2024 15:53:12 -0800 Subject: [PATCH] KVM: x86/mmu: Replace hardcoded value 0 for the initial value for SPTE The TDX support will need the "suppress #VE" bit (bit 63) set as the initial value for SPTE. To reduce code change size, introduce a new macro SHADOW_NONPRESENT_VALUE for the initial value for the shadow page table entry (SPTE) and replace hard-coded value 0 for it. Initialize shadow page tables with their value. The plan is to unconditionally set the "suppress #VE" bit for both AMD and Intel as: 1) AMD hardware uses the bit 63 as NX for present SPTE and ignored for non-present SPTE; 2) for conventional VMX guests, KVM never enables the "EPT-violation #VE" in VMCS control and "suppress #VE" bit is ignored by hardware. No functional change intended. Signed-off-by: Sean Christopherson Signed-off-by: Isaku Yamahata Message-Id: [Remove unnecessary CONFIG_X86_64 check. - Paolo] Reviewed-by: Xiaoyao Li Reviewed-by: Binbin Wu Signed-off-by: Paolo Bonzini --- arch/x86/kvm/mmu/mmu.c | 14 +++++++++----- arch/x86/kvm/mmu/paging_tmpl.h | 2 +- arch/x86/kvm/mmu/spte.h | 4 +++- arch/x86/kvm/mmu/tdp_mmu.c | 12 ++++++------ 4 files changed, 19 insertions(+), 13 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 08900a0563f9..fbfdc606f1f1 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -567,9 +567,9 @@ static u64 mmu_spte_clear_track_bits(struct kvm *kvm, u64 *sptep) if (!is_shadow_present_pte(old_spte) || !spte_has_volatile_bits(old_spte)) - __update_clear_spte_fast(sptep, 0ull); + __update_clear_spte_fast(sptep, SHADOW_NONPRESENT_VALUE); else - old_spte = __update_clear_spte_slow(sptep, 0ull); + old_spte = __update_clear_spte_slow(sptep, SHADOW_NONPRESENT_VALUE); if (!is_shadow_present_pte(old_spte)) return old_spte; @@ -603,7 +603,7 @@ static u64 mmu_spte_clear_track_bits(struct kvm *kvm, u64 *sptep) */ static void mmu_spte_clear_no_track(u64 *sptep) { - __update_clear_spte_fast(sptep, 0ull); + __update_clear_spte_fast(sptep, SHADOW_NONPRESENT_VALUE); } static u64 mmu_spte_get_lockless(u64 *sptep) @@ -1897,7 +1897,8 @@ static bool kvm_sync_page_check(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp) static int kvm_sync_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, int i) { - if (!sp->spt[i]) + /* sp->spt[i] has initial value of shadow page table allocation */ + if (sp->spt[i] == SHADOW_NONPRESENT_VALUE) return 0; return vcpu->arch.mmu->sync_spte(vcpu, sp, i); @@ -6120,7 +6121,10 @@ int kvm_mmu_create(struct kvm_vcpu *vcpu) vcpu->arch.mmu_page_header_cache.kmem_cache = mmu_page_header_cache; vcpu->arch.mmu_page_header_cache.gfp_zero = __GFP_ZERO; - vcpu->arch.mmu_shadow_page_cache.gfp_zero = __GFP_ZERO; + vcpu->arch.mmu_shadow_page_cache.init_value = + SHADOW_NONPRESENT_VALUE; + if (!vcpu->arch.mmu_shadow_page_cache.init_value) + vcpu->arch.mmu_shadow_page_cache.gfp_zero = __GFP_ZERO; vcpu->arch.mmu = &vcpu->arch.root_mmu; vcpu->arch.walk_mmu = &vcpu->arch.root_mmu; diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h index 4d4e98fe4f35..bebd73cd61bb 100644 --- a/arch/x86/kvm/mmu/paging_tmpl.h +++ b/arch/x86/kvm/mmu/paging_tmpl.h @@ -911,7 +911,7 @@ static int FNAME(sync_spte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, int gpa_t pte_gpa; gfn_t gfn; - if (WARN_ON_ONCE(!sp->spt[i])) + if (WARN_ON_ONCE(sp->spt[i] == SHADOW_NONPRESENT_VALUE)) return 0; first_pte_gpa = FNAME(get_level1_sp_gpa)(sp); diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h index f5c600c52f83..0f4ec2859474 100644 --- a/arch/x86/kvm/mmu/spte.h +++ b/arch/x86/kvm/mmu/spte.h @@ -149,6 +149,8 @@ static_assert(MMIO_SPTE_GEN_LOW_BITS == 8 && MMIO_SPTE_GEN_HIGH_BITS == 11); #define MMIO_SPTE_GEN_MASK GENMASK_ULL(MMIO_SPTE_GEN_LOW_BITS + MMIO_SPTE_GEN_HIGH_BITS - 1, 0) +#define SHADOW_NONPRESENT_VALUE 0ULL + extern u64 __read_mostly shadow_host_writable_mask; extern u64 __read_mostly shadow_mmu_writable_mask; extern u64 __read_mostly shadow_nx_mask; @@ -194,7 +196,7 @@ extern u64 __read_mostly shadow_nonpresent_or_rsvd_mask; * * Only used by the TDP MMU. */ -#define REMOVED_SPTE 0x5a0ULL +#define REMOVED_SPTE (SHADOW_NONPRESENT_VALUE | 0x5a0ULL) /* Removed SPTEs must not be misconstrued as shadow present PTEs. */ static_assert(!(REMOVED_SPTE & SPTE_MMU_PRESENT_MASK)); diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index c6192a52bd31..f5401967897a 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -603,7 +603,7 @@ static inline int tdp_mmu_zap_spte_atomic(struct kvm *kvm, * here since the SPTE is going from non-present to non-present. Use * the raw write helper to avoid an unnecessary check on volatile bits. */ - __kvm_tdp_mmu_write_spte(iter->sptep, 0); + __kvm_tdp_mmu_write_spte(iter->sptep, SHADOW_NONPRESENT_VALUE); return 0; } @@ -740,8 +740,8 @@ retry: continue; if (!shared) - tdp_mmu_iter_set_spte(kvm, &iter, 0); - else if (tdp_mmu_set_spte_atomic(kvm, &iter, 0)) + tdp_mmu_iter_set_spte(kvm, &iter, SHADOW_NONPRESENT_VALUE); + else if (tdp_mmu_set_spte_atomic(kvm, &iter, SHADOW_NONPRESENT_VALUE)) goto retry; } } @@ -808,8 +808,8 @@ bool kvm_tdp_mmu_zap_sp(struct kvm *kvm, struct kvm_mmu_page *sp) if (WARN_ON_ONCE(!is_shadow_present_pte(old_spte))) return false; - tdp_mmu_set_spte(kvm, kvm_mmu_page_as_id(sp), sp->ptep, old_spte, 0, - sp->gfn, sp->role.level + 1); + tdp_mmu_set_spte(kvm, kvm_mmu_page_as_id(sp), sp->ptep, old_spte, + SHADOW_NONPRESENT_VALUE, sp->gfn, sp->role.level + 1); return true; } @@ -843,7 +843,7 @@ static bool tdp_mmu_zap_leafs(struct kvm *kvm, struct kvm_mmu_page *root, !is_last_spte(iter.old_spte, iter.level)) continue; - tdp_mmu_iter_set_spte(kvm, &iter, 0); + tdp_mmu_iter_set_spte(kvm, &iter, SHADOW_NONPRESENT_VALUE); /* * Zappings SPTEs in invalid roots doesn't require a TLB flush, -- 2.25.1