From: Jim Mattson <jmattson@google.com>
To: kvm@vger.kernel.org, pbonzini@redhat.com
Cc: Jim Mattson <jmattson@google.com>
Subject: [PATCH v2 07/12] KVM: nVMX: Disable vmcs02 posted interrupts if vmcs12 PID isn't mappable
Date: Fri, 4 Jun 2021 10:26:06 -0700 [thread overview]
Message-ID: <20210604172611.281819-8-jmattson@google.com> (raw)
In-Reply-To: <20210604172611.281819-1-jmattson@google.com>
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>
---
arch/x86/kvm/vmx/nested.c | 15 ++++++++++++++-
1 file changed, 14 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 706c31821362..632f0abfe154 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -3175,6 +3175,15 @@ 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))
@@ -3689,10 +3698,14 @@ 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;
--
2.32.0.rc1.229.g3e70b5a671-goog
next prev parent reply other threads:[~2021-06-04 17:26 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-04 17:25 [PATCH v2 00/12] KVM: nVMX: Fix vmcs02 PID use-after-free issue Jim Mattson
2021-06-04 17:26 ` [PATCH v2 01/12] KVM: x86: Remove guest mode check from kvm_check_nested_events Jim Mattson
2021-06-04 17:26 ` [PATCH v2 02/12] KVM: x86: Wake up a vCPU when kvm_check_nested_events fails Jim Mattson
2021-06-04 17:26 ` [PATCH v2 03/12] KVM: nVMX: Add a return code to vmx_complete_nested_posted_interrupt Jim Mattson
2021-06-04 17:26 ` [PATCH v2 04/12] KVM: x86: Add a return code to inject_pending_event Jim Mattson
2021-06-04 17:26 ` [PATCH v2 05/12] KVM: x86: Add a return code to kvm_apic_accept_events Jim Mattson
2021-06-04 17:26 ` [PATCH v2 06/12] KVM: nVMX: Fail on MMIO completion for nested posted interrupts Jim Mattson
2021-06-04 17:26 ` Jim Mattson [this message]
2021-06-04 17:26 ` [PATCH v2 08/12] KVM: selftests: Move APIC definitions into a separate file Jim Mattson
2021-06-04 17:26 ` [PATCH v2 09/12] KVM: selftests: Hoist APIC functions out of individual tests Jim Mattson
2021-06-04 17:26 ` [PATCH v2 10/12] KVM: selftests: Introduce x2APIC register manipulation functions Jim Mattson
2021-06-04 17:26 ` [PATCH v2 11/12] KVM: selftests: Introduce prepare_tpr_shadow Jim Mattson
2021-06-04 17:26 ` [PATCH v2 12/12] KVM: selftests: Add a test of an unbacked nested PI descriptor Jim Mattson
2021-06-10 11:55 ` [PATCH v2 00/12] KVM: nVMX: Fix vmcs02 PID use-after-free issue Paolo Bonzini
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