diff options
| author | Sean Christopherson <seanjc@google.com> | 2021-09-06 20:25:46 +0800 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2021-10-01 03:44:52 -0400 |
| commit | b1a429fb18011505acad931f409415c8bb5b5c28 (patch) | |
| tree | 61e1f37eade608e021179df0e622d9b2756da70d /arch/x86/kvm/mmu | |
| parent | f0066d94c92dc5cf7f1a272a1bd324b0fc575292 (diff) | |
KVM: x86/mmu: Verify shadow walk doesn't terminate early in page faults
WARN and bail if the shadow walk for faulting in a SPTE terminates early,
i.e. doesn't reach the expected level because the walk encountered a
terminal SPTE. The shadow walks for page faults are subtle in that they
install non-leaf SPTEs (zapping leaf SPTEs if necessary!) in the loop
body, and consume the newly created non-leaf SPTE in the loop control,
e.g. __shadow_walk_next(). In other words, the walks guarantee that the
walk will stop if and only if the target level is reached by installing
non-leaf SPTEs to guarantee the walk remains valid.
Opportunistically use fault->goal-level instead of it.level in
FNAME(fetch) to further clarify that KVM always installs the leaf SPTE at
the target level.
Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Message-Id: <20210906122547.263316-1-jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm/mmu')
| -rw-r--r-- | arch/x86/kvm/mmu/mmu.c | 3 | ||||
| -rw-r--r-- | arch/x86/kvm/mmu/paging_tmpl.h | 7 |
2 files changed, 8 insertions, 2 deletions
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 5ba0a844f576..2ddbabad5bd2 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -3012,6 +3012,9 @@ static int __direct_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) account_huge_nx_page(vcpu->kvm, sp); } + if (WARN_ON_ONCE(it.level != fault->goal_level)) + return -EFAULT; + ret = mmu_set_spte(vcpu, it.sptep, ACC_ALL, fault->write, fault->goal_level, base_gfn, fault->pfn, fault->prefault, fault->map_writable); diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h index 6bc0dbc0baff..7a8a2d14a3c7 100644 --- a/arch/x86/kvm/mmu/paging_tmpl.h +++ b/arch/x86/kvm/mmu/paging_tmpl.h @@ -760,9 +760,12 @@ static int FNAME(fetch)(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault, } } + if (WARN_ON_ONCE(it.level != fault->goal_level)) + return -EFAULT; + ret = mmu_set_spte(vcpu, it.sptep, gw->pte_access, fault->write, - it.level, base_gfn, fault->pfn, fault->prefault, - fault->map_writable); + fault->goal_level, base_gfn, fault->pfn, + fault->prefault, fault->map_writable); if (ret == RET_PF_SPURIOUS) return ret; |