diff options
| author | Avi Kivity <avi@redhat.com> | 2011-06-06 16:11:54 +0300 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2011-07-12 13:16:26 +0300 |
| commit | 411c588dfb863feee78b721d5e7c86ac38921c49 (patch) | |
| tree | bb60c136f0392fbbd8f222fd2049f265746a7eae /arch/x86 | |
| parent | a01c8f9b4e266df1d7166d23216f2060648f862d (diff) | |
KVM: MMU: Adjust shadow paging to work when SMEP=1 and CR0.WP=0
When CR0.WP=0, we sometimes map user pages as kernel pages (to allow
the kernel to write to them). Unfortunately this also allows the kernel
to fetch from these pages, even if CR4.SMEP is set.
Adjust for this by also setting NX on the spte in these circumstances.
Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/include/asm/kvm_host.h | 1 | ||||
| -rw-r--r-- | arch/x86/kvm/mmu.c | 14 |
2 files changed, 14 insertions, 1 deletions
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 554be456f11e..da6bbee878ca 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -205,6 +205,7 @@ union kvm_mmu_page_role { unsigned invalid:1; unsigned nxe:1; unsigned cr0_wp:1; + unsigned smep_andnot_wp:1; }; }; diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 15afa1e1eaf9..da0f3b081076 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -1985,8 +1985,17 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep, spte |= PT_WRITABLE_MASK; if (!vcpu->arch.mmu.direct_map - && !(pte_access & ACC_WRITE_MASK)) + && !(pte_access & ACC_WRITE_MASK)) { spte &= ~PT_USER_MASK; + /* + * If we converted a user page to a kernel page, + * so that the kernel can write to it when cr0.wp=0, + * then we should prevent the kernel from executing it + * if SMEP is enabled. + */ + if (kvm_read_cr4_bits(vcpu, X86_CR4_SMEP)) + spte |= PT64_NX_MASK; + } /* * Optimization: for pte sync, if spte was writable the hash @@ -2955,6 +2964,7 @@ static int init_kvm_tdp_mmu(struct kvm_vcpu *vcpu) int kvm_init_shadow_mmu(struct kvm_vcpu *vcpu, struct kvm_mmu *context) { int r; + bool smep = kvm_read_cr4_bits(vcpu, X86_CR4_SMEP); ASSERT(vcpu); ASSERT(!VALID_PAGE(vcpu->arch.mmu.root_hpa)); @@ -2969,6 +2979,8 @@ int kvm_init_shadow_mmu(struct kvm_vcpu *vcpu, struct kvm_mmu *context) vcpu->arch.mmu.base_role.cr4_pae = !!is_pae(vcpu); vcpu->arch.mmu.base_role.cr0_wp = is_write_protection(vcpu); + vcpu->arch.mmu.base_role.smep_andnot_wp + = smep && !is_write_protection(vcpu); return r; } |