diff options
| author | Jim Mattson <jmattson@google.com> | 2021-06-04 10:26:06 -0700 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2021-06-17 13:09:31 -0400 |
| commit | 966eefb8965798478c2a6de3aa35ec180323792d (patch) | |
| tree | edca2b0535056e70c21acdc1cb91ab1c8faa4c2b | |
| parent | 0fe998b295a37234392072c23e22b8bba4774d0f (diff) | |
KVM: nVMX: Disable vmcs02 posted interrupts if vmcs12 PID isn't mappable
Don't allow posted interrupts to modify a stale posted interrupt
descriptor (including the initial value of 0).
Empirical tests on real hardware reveal that a posted interrupt
descriptor referencing an unbacked address has PCI bus error semantics
(reads as all 1's; writes are ignored). However, kvm can't distinguish
unbacked addresses from device-backed (MMIO) addresses, so it should
really ask userspace for an MMIO completion. That's overly
complicated, so just punt with KVM_INTERNAL_ERROR.
Don't return the error until the posted interrupt descriptor is
actually accessed. We don't want to break the existing kvm-unit-tests
that assume they can launch an L2 VM with a posted interrupt
descriptor that references MMIO space in L1.
Fixes: 6beb7bd52e48 ("kvm: nVMX: Refactor nested_get_vmcs12_pages()")
Signed-off-by: Jim Mattson <jmattson@google.com>
Message-Id: <20210604172611.281819-8-jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| -rw-r--r-- | arch/x86/kvm/vmx/nested.c | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index 4e545996440b..98b5f5f104da 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -3184,6 +3184,15 @@ static bool nested_get_vmcs12_pages(struct kvm_vcpu *vcpu) offset_in_page(vmcs12->posted_intr_desc_addr)); vmcs_write64(POSTED_INTR_DESC_ADDR, pfn_to_hpa(map->pfn) + offset_in_page(vmcs12->posted_intr_desc_addr)); + } else { + /* + * Defer the KVM_INTERNAL_EXIT until KVM tries to + * access the contents of the VMCS12 posted interrupt + * descriptor. (Note that KVM may do this when it + * should not, per the architectural specification.) + */ + vmx->nested.pi_desc = NULL; + pin_controls_clearbit(vmx, PIN_BASED_POSTED_INTR); } } if (nested_vmx_prepare_msr_bitmap(vcpu, vmcs12)) @@ -3696,10 +3705,14 @@ static int vmx_complete_nested_posted_interrupt(struct kvm_vcpu *vcpu) void *vapic_page; u16 status; - if (!vmx->nested.pi_desc || !vmx->nested.pi_pending) + if (!vmx->nested.pi_pending) return 0; + if (!vmx->nested.pi_desc) + goto mmio_needed; + vmx->nested.pi_pending = false; + if (!pi_test_and_clear_on(vmx->nested.pi_desc)) return 0; |