diff options
| author | Bandan Das <bsd@redhat.com> | 2016-07-12 18:18:51 -0400 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2016-07-14 09:03:50 +0200 |
| commit | d95c55687e11febe3ab1aacfe82b58b1822c52c4 (patch) | |
| tree | ef950c000f877fbbc19181bfcfa2f590cecc37ba /arch/x86/kvm/mmu.c | |
| parent | ffb128c89b77b44da18ccf51844a8e750e2c427a (diff) | |
kvm: mmu: track read permission explicitly for shadow EPT page tables
To support execute only mappings on behalf of L1 hypervisors,
reuse ACC_USER_MASK to signify if the L1 hypervisor has the R bit
set.
For the nested EPT case, we assumed that the U bit was always set
since there was no equivalent in EPT page tables. Strictly
speaking, this was not necessary because handle_ept_violation
never set PFERR_USER_MASK in the error code (uf=0 in the
parlance of update_permission_bitmask). We now have to set
both U and UF correctly, respectively in FNAME(gpte_access)
and in handle_ept_violation.
Also in handle_ept_violation bit 3 of the exit qualification is
not enough to detect a present PTE; all three bits 3-5 have to
be checked.
Signed-off-by: Bandan Das <bsd@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm/mmu.c')
| -rw-r--r-- | arch/x86/kvm/mmu.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index b8628e905806..3041902ec827 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -2522,6 +2522,12 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep, if (set_mmio_spte(vcpu, sptep, gfn, pfn, pte_access)) return 0; + /* + * For the EPT case, shadow_present_mask is 0 if hardware + * supports exec-only page table entries. In that case, + * ACC_USER_MASK and shadow_user_mask are used to represent + * read access. See FNAME(gpte_access) in paging_tmpl.h. + */ spte |= shadow_present_mask; if (!speculative) spte |= shadow_accessed_mask; @@ -3915,9 +3921,7 @@ static void update_permission_bitmask(struct kvm_vcpu *vcpu, * clearer. */ smap = cr4_smap && u && !uf && !ff; - } else - /* Not really needed: no U/S accesses on ept */ - u = 1; + } fault = (ff && !x) || (uf && !u) || (wf && !w) || (smapf && smap); |