From: Avi Kivity <[email protected]> Add a helper to verify that a direct shadow page is valid wrt the required access permissions; drop the page if it is not valid.
Reviewed-by: Xiao Guangrong <[email protected]> Signed-off-by: Avi Kivity <[email protected]> Signed-off-by: Marcelo Tosatti <[email protected]> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 747af72..d16efbe 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -1500,6 +1500,29 @@ static void drop_large_spte(struct kvm_vcpu *vcpu, u64 *sptep) } } +static void validate_direct_spte(struct kvm_vcpu *vcpu, u64 *sptep, + unsigned direct_access) +{ + if (is_shadow_present_pte(*sptep) && !is_large_pte(*sptep)) { + struct kvm_mmu_page *child; + + /* + * For the direct sp, if the guest pte's dirty bit + * changed form clean to dirty, it will corrupt the + * sp's access: allow writable in the read-only sp, + * so we should update the spte at this point to get + * a new sp with the correct access. + */ + child = page_header(*sptep & PT64_BASE_ADDR_MASK); + if (child->role.access == direct_access) + return; + + mmu_page_remove_parent_pte(child, sptep); + __set_spte(sptep, shadow_trap_nonpresent_pte); + kvm_flush_remote_tlbs(vcpu->kvm); + } +} + static void kvm_mmu_page_unlink_children(struct kvm *kvm, struct kvm_mmu_page *sp) { diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h index 69dcac0..893a75c 100644 --- a/arch/x86/kvm/paging_tmpl.h +++ b/arch/x86/kvm/paging_tmpl.h @@ -338,30 +338,15 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr, break; } - if (is_shadow_present_pte(*sptep) && !is_large_pte(*sptep)) { - struct kvm_mmu_page *child; - - if (level != gw->level) - continue; - - /* - * For the direct sp, if the guest pte's dirty bit - * changed form clean to dirty, it will corrupt the - * sp's access: allow writable in the read-only sp, - * so we should update the spte at this point to get - * a new sp with the correct access. - */ - child = page_header(*sptep & PT64_BASE_ADDR_MASK); - if (child->role.access == direct_access) - continue; - - mmu_page_remove_parent_pte(child, sptep); - __set_spte(sptep, shadow_trap_nonpresent_pte); - kvm_flush_remote_tlbs(vcpu->kvm); - } + if (is_shadow_present_pte(*sptep) && !is_large_pte(*sptep) + && level == gw->level) + validate_direct_spte(vcpu, sptep, direct_access); drop_large_spte(vcpu, sptep); + if (is_shadow_present_pte(*sptep)) + continue; + if (level <= gw->level) { direct = 1; access = direct_access; -- To unsubscribe from this list: send the line "unsubscribe kvm-commits" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
