From: Sean Christopherson <seanjc@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Oliver Upton <oupton@google.com>, Peter Shier <pshier@google.com>
Subject: [PATCH 02/21] KVM: nVMX: Unconditionally purge queued/injected events on nested "exit"
Date: Fri, 11 Mar 2022 03:27:42 +0000 [thread overview]
Message-ID: <20220311032801.3467418-3-seanjc@google.com> (raw)
In-Reply-To: <20220311032801.3467418-1-seanjc@google.com>
Drop pending exceptions and events queued for re-injection when leaving
nested guest mode, even if the "exit" is due to VM-Fail, SMI, or forced
by host userspace. Failure to purge events could result in an event
belonging to L2 being injected into L1.
This _should_ never happen for VM-Fail as all events should be blocked by
nested_run_pending, but it's possible if KVM, not the L1 hypervisor, is
the source of VM-Fail when running vmcs02.
SMI is a nop (barring unknown bugs) as recognition of SMI and thus entry
to SMM is blocked by pending exceptions and re-injected events.
Forced exit is definitely buggy, but has likely gone unnoticed because
userspace probably follows the forced exit with KVM_SET_VCPU_EVENTS (or
some other ioctl() that purges the queue).
Fixes: 4f350c6dbcb9 ("kvm: nVMX: Handle deferred early VMLAUNCH/VMRESUME failure properly")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/vmx/nested.c | 19 +++++++++++--------
1 file changed, 11 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index f18744f7ff82..f09c6eff7af9 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -4233,14 +4233,6 @@ static void prepare_vmcs12(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
nested_vmx_abort(vcpu,
VMX_ABORT_SAVE_GUEST_MSR_FAIL);
}
-
- /*
- * Drop what we picked up for L2 via vmx_complete_interrupts. It is
- * preserved above and would only end up incorrectly in L1.
- */
- vcpu->arch.nmi_injected = false;
- kvm_clear_exception_queue(vcpu);
- kvm_clear_interrupt_queue(vcpu);
}
/*
@@ -4582,6 +4574,17 @@ void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 vm_exit_reason,
WARN_ON_ONCE(nested_early_check);
}
+ /*
+ * Drop events/exceptions that were queued for re-injection to L2
+ * (picked up via vmx_complete_interrupts()), as well as exceptions
+ * that were pending for L2. Note, this must NOT be hoisted above
+ * prepare_vmcs12(), events/exceptions queued for re-injection need to
+ * be captured in vmcs12 (see vmcs12_save_pending_event()).
+ */
+ vcpu->arch.nmi_injected = false;
+ kvm_clear_exception_queue(vcpu);
+ kvm_clear_interrupt_queue(vcpu);
+
vmx_switch_vmcs(vcpu, &vmx->vmcs01);
/* Update any VMCS fields that might have changed while L2 ran */
--
2.35.1.723.g4982287a31-goog
next prev parent reply other threads:[~2022-03-11 3:28 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-11 3:27 [PATCH 00/21] KVM: x86: Event/exception fixes and cleanups Sean Christopherson
2022-03-11 3:27 ` [PATCH 01/21] KVM: x86: Return immediately from x86_emulate_instruction() on code #DB Sean Christopherson
2022-03-11 3:27 ` Sean Christopherson [this message]
2022-03-11 3:27 ` [PATCH 03/21] KVM: VMX: Drop bits 31:16 when shoving exception error code into VMCS Sean Christopherson
2022-03-11 3:27 ` [PATCH 04/21] KVM: x86: Don't check for code breakpoints when emulating on exception Sean Christopherson
2022-03-11 3:27 ` [PATCH 05/21] KVM: nVMX: Treat General Detect #DB (DR7.GD=1) as fault-like Sean Christopherson
2022-03-11 3:27 ` [PATCH 06/21] KVM: nVMX: Prioritize TSS T-flag #DBs over Monitor Trap Flag Sean Christopherson
2022-03-11 3:27 ` [PATCH 07/21] KVM: x86: Treat #DBs from the emulator as fault-like (code and DR7.GD=1) Sean Christopherson
2022-03-11 3:27 ` [PATCH 08/21] KVM: x86: Use DR7_GD macro instead of open coding check in emulator Sean Christopherson
2022-03-11 3:27 ` [PATCH 09/21] KVM: nVMX: Ignore SIPI that arrives in L2 when vCPU is not in WFS Sean Christopherson
2022-03-11 3:27 ` [PATCH 10/21] KVM: nVMX: Unconditionally clear mtf_pending on nested VM-Exit Sean Christopherson
2022-03-11 3:27 ` [PATCH 11/21] KVM: VMX: Inject #PF on ENCLS as "emulated" #PF Sean Christopherson
2022-03-11 3:27 ` [PATCH 12/21] KVM: x86: Rename kvm_x86_ops.queue_exception to inject_exception Sean Christopherson
2022-03-11 3:27 ` [PATCH 13/21] KVM: x86: Make kvm_queued_exception a properly named, visible struct Sean Christopherson
2022-03-11 3:27 ` [PATCH 14/21] KVM: x86: Formalize blocking of nested pending exceptions Sean Christopherson
2022-03-11 3:27 ` [PATCH 15/21] KVM: x86: Use kvm_queue_exception_e() to queue #DF Sean Christopherson
2022-03-11 3:27 ` [PATCH 16/21] KVM: x86: Hoist nested event checks above event injection logic Sean Christopherson
2022-03-11 3:27 ` [PATCH 17/21] KVM: x86: Evaluate ability to inject SMI/NMI/IRQ after potential VM-Exit Sean Christopherson
2022-03-11 3:27 ` [PATCH 18/21] KVM: x86: Morph pending exceptions to pending VM-Exits at queue time Sean Christopherson
2022-03-11 3:27 ` [PATCH 19/21] KVM: VMX: Update MTF and ICEBP comments to document KVM's subtle behavior Sean Christopherson
2022-03-11 3:28 ` [PATCH 20/21] KVM: selftests: Use uapi header to get VMX and SVM exit reasons/codes Sean Christopherson
2022-03-11 3:28 ` [PATCH 21/21] KVM: selftests: Add an x86-only test to verify nested exception queueing Sean Christopherson
2022-03-11 16:30 ` [PATCH 00/21] KVM: x86: Event/exception fixes and cleanups Maciej S. Szmigiero
2022-03-13 9:22 ` Maxim Levitsky
2022-03-24 21:31 ` Sean Christopherson
2022-03-25 21:25 ` Maciej S. Szmigiero
2022-03-25 23:02 ` Sean Christopherson
2022-03-26 0:21 ` Maciej S. Szmigiero
2022-03-27 15:06 ` Maxim Levitsky
2022-03-28 17:50 ` Sean Christopherson
2022-03-29 10:45 ` Maxim Levitsky
2022-03-29 15:43 ` Sean Christopherson
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