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| author | Avi Kivity | 2010-07-13 13:27:07 +0200 |
|---|---|---|
| committer | Avi Kivity | 2010-08-02 05:40:43 +0200 |
| commit | a357bd229cdaf37a41798d238ab50b34c71dd0d6 (patch) | |
| tree | 0a2801b53c7df2c8494bc5c572574cb29ad4aeee /arch/x86/kvm/mmu.c | |
| parent | KVM: MMU: Add drop_large_spte() helper (diff) | |
| download | kernel-qcow2-linux-a357bd229cdaf37a41798d238ab50b34c71dd0d6.tar.gz kernel-qcow2-linux-a357bd229cdaf37a41798d238ab50b34c71dd0d6.tar.xz kernel-qcow2-linux-a357bd229cdaf37a41798d238ab50b34c71dd0d6.zip | |
KVM: MMU: Add validate_direct_spte() helper
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 <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Diffstat (limited to 'arch/x86/kvm/mmu.c')
| -rw-r--r-- | arch/x86/kvm/mmu.c | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index b75d6cb44ab6..36c62f33513f 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) { |