From 36d9594dfbf22a59adb986d85e0543886ab898f2 Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov Date: Mon, 8 Oct 2018 21:28:10 +0200 Subject: [PATCH] x86/kvm/mmu: make space for source data caching in struct kvm_mmu In preparation to MMU reconfiguration avoidance we need a space to cache source data. As this partially intersects with kvm_mmu_page_role, create 64bit sized union kvm_mmu_role holding both base and extended data. No functional change. Signed-off-by: Vitaly Kuznetsov Reviewed-by: Sean Christopherson Signed-off-by: Paolo Bonzini --- arch/x86/include/asm/kvm_host.h | 16 ++++++++++++++-- arch/x86/kvm/mmu.c | 26 ++++++++++++++++++++------ arch/x86/kvm/vmx.c | 2 +- 3 files changed, 35 insertions(+), 9 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 992bc1058170..51ce635494b0 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -256,7 +256,7 @@ struct kvm_mmu_memory_cache { * @nxe, @cr0_wp, @smep_andnot_wp and @smap_andnot_wp. */ union kvm_mmu_page_role { - unsigned word; + u32 word; struct { unsigned level:4; unsigned cr4_pae:1; @@ -282,6 +282,18 @@ union kvm_mmu_page_role { }; }; +union kvm_mmu_extended_role { + u32 word; +}; + +union kvm_mmu_role { + u64 as_u64; + struct { + union kvm_mmu_page_role base; + union kvm_mmu_extended_role ext; + }; +}; + struct kvm_rmap_head { unsigned long val; }; @@ -369,7 +381,7 @@ struct kvm_mmu { void (*update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, u64 *spte, const void *pte); hpa_t root_hpa; - union kvm_mmu_page_role base_role; + union kvm_mmu_role mmu_role; u8 root_level; u8 shadow_root_level; u8 ept_ad; diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index dd147fa5b3f4..3301973527aa 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -2375,7 +2375,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, int collisions = 0; LIST_HEAD(invalid_list); - role = vcpu->arch.mmu->base_role; + role = vcpu->arch.mmu->mmu_role.base; role.level = level; role.direct = direct; if (role.direct) @@ -4423,7 +4423,8 @@ static void reset_rsvds_bits_mask_ept(struct kvm_vcpu *vcpu, void reset_shadow_zero_bits_mask(struct kvm_vcpu *vcpu, struct kvm_mmu *context) { - bool uses_nx = context->nx || context->base_role.smep_andnot_wp; + bool uses_nx = context->nx || + context->mmu_role.base.smep_andnot_wp; struct rsvd_bits_validate *shadow_zero_check; int i; @@ -4742,7 +4743,7 @@ static void init_kvm_tdp_mmu(struct kvm_vcpu *vcpu) { struct kvm_mmu *context = vcpu->arch.mmu; - context->base_role.word = mmu_base_role_mask.word & + context->mmu_role.base.word = mmu_base_role_mask.word & kvm_calc_tdp_mmu_root_page_role(vcpu).word; context->page_fault = tdp_page_fault; context->sync_page = nonpaging_sync_page; @@ -4823,7 +4824,7 @@ void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu) else paging32_init_context(vcpu, context); - context->base_role.word = mmu_base_role_mask.word & + context->mmu_role.base.word = mmu_base_role_mask.word & kvm_calc_shadow_mmu_root_page_role(vcpu).word; reset_shadow_zero_bits_mask(vcpu, context); } @@ -4865,7 +4866,8 @@ void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly, context->update_pte = ept_update_pte; context->root_level = PT64_ROOT_4LEVEL; context->direct_map = false; - context->base_role.word = root_page_role.word & mmu_base_role_mask.word; + context->mmu_role.base.word = + root_page_role.word & mmu_base_role_mask.word; update_permission_bitmask(vcpu, context, true); update_pkru_bitmask(vcpu, context, true); @@ -5179,10 +5181,12 @@ static void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, local_flush = true; while (npte--) { + u32 base_role = vcpu->arch.mmu->mmu_role.base.word; + entry = *spte; mmu_page_zap_pte(vcpu->kvm, sp, spte); if (gentry && - !((sp->role.word ^ vcpu->arch.mmu->base_role.word) + !((sp->role.word ^ base_role) & mmu_base_role_mask.word) && rmap_can_add(vcpu)) mmu_pte_write_new_pte(vcpu, sp, spte, &gentry); if (need_remote_flush(entry, *spte)) @@ -5879,6 +5883,16 @@ int kvm_mmu_module_init(void) { int ret = -ENOMEM; + /* + * MMU roles use union aliasing which is, generally speaking, an + * undefined behavior. However, we supposedly know how compilers behave + * and the current status quo is unlikely to change. Guardians below are + * supposed to let us know if the assumption becomes false. + */ + BUILD_BUG_ON(sizeof(union kvm_mmu_page_role) != sizeof(u32)); + BUILD_BUG_ON(sizeof(union kvm_mmu_extended_role) != sizeof(u32)); + BUILD_BUG_ON(sizeof(union kvm_mmu_role) != sizeof(u64)); + kvm_mmu_reset_all_pte_masks(); pte_list_desc_cache = kmem_cache_create("pte_list_desc", diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 02888031d038..6f44d3a63434 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -9263,7 +9263,7 @@ static int nested_vmx_eptp_switching(struct kvm_vcpu *vcpu, kvm_mmu_unload(vcpu); mmu->ept_ad = accessed_dirty; - mmu->base_role.ad_disabled = !accessed_dirty; + mmu->mmu_role.base.ad_disabled = !accessed_dirty; vmcs12->ept_pointer = address; /* * TODO: Check what's the correct approach in case -- 2.30.2