The sptes on the middle level should obey these rules: - they are always writable - they are not pointing to process's page, so that SPTE_HOST_WRITEABLE has no chance to be set
So we can check last spte by using PT_WRITABLE_MASK and SPTE_HOST_WRITEABLE that can be got from spte, then we can let is_last_spte() do not depend on the mapping level anymore This is important to implement lockless write-protection since only spte is available at that time Signed-off-by: Xiao Guangrong <[email protected]> --- arch/x86/kvm/mmu.c | 25 ++++++++++++------------- arch/x86/kvm/mmu_audit.c | 6 +++--- arch/x86/kvm/paging_tmpl.h | 6 ++---- 3 files changed, 17 insertions(+), 20 deletions(-) diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 5b42858..8b96d96 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -337,13 +337,13 @@ static int is_rmap_spte(u64 pte) return is_shadow_present_pte(pte); } -static int is_last_spte(u64 pte, int level) +static int is_last_spte(u64 pte) { - if (level == PT_PAGE_TABLE_LEVEL) - return 1; - if (is_large_pte(pte)) - return 1; - return 0; + /* + * All the sptes on the middle level are writable but + * SPTE_HOST_WRITEABLE is not set. + */ + return !(is_writable_pte(pte) && !(pte & SPTE_HOST_WRITEABLE)); } static pfn_t spte_to_pfn(u64 pte) @@ -2203,7 +2203,7 @@ static bool shadow_walk_okay(struct kvm_shadow_walk_iterator *iterator) static void __shadow_walk_next(struct kvm_shadow_walk_iterator *iterator, u64 spte) { - if (is_last_spte(spte, iterator->level)) { + if (is_last_spte(spte)) { iterator->level = 0; return; } @@ -2255,15 +2255,14 @@ static void validate_direct_spte(struct kvm_vcpu *vcpu, u64 *sptep, } } -static bool mmu_page_zap_pte(struct kvm *kvm, struct kvm_mmu_page *sp, - u64 *spte) +static bool mmu_page_zap_pte(struct kvm *kvm, u64 *spte) { u64 pte; struct kvm_mmu_page *child; pte = *spte; if (is_shadow_present_pte(pte)) { - if (is_last_spte(pte, sp->role.level)) { + if (is_last_spte(pte)) { drop_spte(kvm, spte); if (is_large_pte(pte)) --kvm->stat.lpages; @@ -2286,7 +2285,7 @@ static void kvm_mmu_page_unlink_children(struct kvm *kvm, unsigned i; for (i = 0; i < PT64_ENT_PER_PAGE; ++i) - mmu_page_zap_pte(kvm, sp, sp->spt + i); + mmu_page_zap_pte(kvm, sp->spt + i); } static void kvm_mmu_put_page(struct kvm_mmu_page *sp, u64 *parent_pte) @@ -3068,7 +3067,7 @@ static bool fast_page_fault(struct kvm_vcpu *vcpu, gva_t gva, int level, } sp = page_header(__pa(iterator.sptep)); - if (!is_last_spte(spte, sp->role.level)) + if (!is_last_spte(spte)) goto exit; /* @@ -4316,7 +4315,7 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, local_flush = true; while (npte--) { entry = *spte; - mmu_page_zap_pte(vcpu->kvm, sp, spte); + mmu_page_zap_pte(vcpu->kvm, spte); if (gentry && !((sp->role.word ^ vcpu->arch.mmu.base_role.word) & mask.word) && rmap_can_add(vcpu)) diff --git a/arch/x86/kvm/mmu_audit.c b/arch/x86/kvm/mmu_audit.c index daff69e..d54e2ad 100644 --- a/arch/x86/kvm/mmu_audit.c +++ b/arch/x86/kvm/mmu_audit.c @@ -45,7 +45,7 @@ static void __mmu_spte_walk(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, fn(vcpu, ent + i, level); if (is_shadow_present_pte(ent[i]) && - !is_last_spte(ent[i], level)) { + !is_last_spte(ent[i])) { struct kvm_mmu_page *child; child = page_header(ent[i] & PT64_BASE_ADDR_MASK); @@ -110,7 +110,7 @@ static void audit_mappings(struct kvm_vcpu *vcpu, u64 *sptep, int level) } } - if (!is_shadow_present_pte(*sptep) || !is_last_spte(*sptep, level)) + if (!is_shadow_present_pte(*sptep) || !is_last_spte(*sptep)) return; gfn = kvm_mmu_page_get_gfn(sp, sptep - sp->spt); @@ -158,7 +158,7 @@ static void inspect_spte_has_rmap(struct kvm *kvm, u64 *sptep) static void audit_sptes_have_rmaps(struct kvm_vcpu *vcpu, u64 *sptep, int level) { - if (is_shadow_present_pte(*sptep) && is_last_spte(*sptep, level)) + if (is_shadow_present_pte(*sptep) && is_last_spte(*sptep)) inspect_spte_has_rmap(vcpu->kvm, sptep); } diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h index ad75d77..33f0216 100644 --- a/arch/x86/kvm/paging_tmpl.h +++ b/arch/x86/kvm/paging_tmpl.h @@ -809,7 +809,6 @@ static void FNAME(invlpg)(struct kvm_vcpu *vcpu, gva_t gva) { struct kvm_shadow_walk_iterator iterator; struct kvm_mmu_page *sp; - int level; u64 *sptep; vcpu_clear_mmio_info(vcpu, gva); @@ -822,11 +821,10 @@ static void FNAME(invlpg)(struct kvm_vcpu *vcpu, gva_t gva) spin_lock(&vcpu->kvm->mmu_lock); for_each_shadow_entry(vcpu, gva, iterator) { - level = iterator.level; sptep = iterator.sptep; sp = page_header(__pa(sptep)); - if (is_last_spte(*sptep, level)) { + if (is_last_spte(*sptep)) { pt_element_t gpte; gpa_t pte_gpa; @@ -836,7 +834,7 @@ static void FNAME(invlpg)(struct kvm_vcpu *vcpu, gva_t gva) pte_gpa = FNAME(get_level1_sp_gpa)(sp); pte_gpa += (sptep - sp->spt) * sizeof(pt_element_t); - if (mmu_page_zap_pte(vcpu->kvm, sp, sptep)) + if (mmu_page_zap_pte(vcpu->kvm, sptep)) kvm_flush_remote_tlbs(vcpu->kvm); if (!rmap_can_add(vcpu)) -- 1.8.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
