From: Sean Christopherson <seanjc@google.com>
To: Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Jim Mattson <jmattson@google.com>,
Maxim Levitsky <mlevitsk@redhat.com>,
Oliver Upton <oupton@google.com>, Peter Shier <pshier@google.com>
Subject: [PATCH v5 07/27] KVM: nVMX: Prioritize TSS T-flag #DBs over Monitor Trap Flag
Date: Tue, 30 Aug 2022 23:15:54 +0000 [thread overview]
Message-ID: <20220830231614.3580124-8-seanjc@google.com> (raw)
In-Reply-To: <20220830231614.3580124-1-seanjc@google.com>
Service TSS T-flag #DBs prior to pending MTFs, as such #DBs are higher
priority than MTF. KVM itself doesn't emulate TSS #DBs, and any such
exceptions injected from L1 will be handled by hardware (or morphed to
a fault-like exception if injection fails), but theoretically userspace
could pend a TSS T-flag #DB in conjunction with a pending MTF.
Note, there's no known use case this fixes, it's purely to be technically
correct with respect to Intel's SDM.
Cc: Oliver Upton <oupton@google.com>
Cc: Peter Shier <pshier@google.com>
Fixes: 5ef8acbdd687 ("KVM: nVMX: Emulate MTF when performing instruction emulation")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
---
arch/x86/kvm/vmx/nested.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index b540c7bf4753..5298457b3a1f 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -3939,15 +3939,17 @@ static int vmx_check_nested_events(struct kvm_vcpu *vcpu)
}
/*
- * Process any exceptions that are not debug traps before MTF.
+ * Process exceptions that are higher priority than Monitor Trap Flag:
+ * fault-like exceptions, TSS T flag #DB (not emulated by KVM, but
+ * could theoretically come in from userspace), and ICEBP (INT1).
*
* Note that only a pending nested run can block a pending exception.
* Otherwise an injected NMI/interrupt should either be
* lost or delivered to the nested hypervisor in the IDT_VECTORING_INFO,
* while delivering the pending exception.
*/
-
- if (vcpu->arch.exception.pending && !vmx_get_pending_dbg_trap(vcpu)) {
+ if (vcpu->arch.exception.pending &&
+ !(vmx_get_pending_dbg_trap(vcpu) & ~DR6_BT)) {
if (vmx->nested.nested_run_pending)
return -EBUSY;
if (!nested_vmx_check_exception(vcpu, &exit_qual))
--
2.37.2.672.g94769d06f0-goog
next prev parent reply other threads:[~2022-08-30 23:18 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-30 23:15 [PATCH v5 00/27] KVM: x86: Event/exception fixes and cleanups Sean Christopherson
2022-08-30 23:15 ` [PATCH v5 01/27] KVM: nVMX: Unconditionally purge queued/injected events on nested "exit" Sean Christopherson
2022-08-30 23:15 ` [PATCH v5 02/27] KVM: VMX: Drop bits 31:16 when shoving exception error code into VMCS Sean Christopherson
2022-08-30 23:15 ` [PATCH v5 03/27] KVM: x86: Don't check for code breakpoints when emulating on exception Sean Christopherson
2022-08-30 23:15 ` [PATCH v5 04/27] KVM: x86: Allow clearing RFLAGS.RF on forced emulation to test code #DBs Sean Christopherson
2022-08-30 23:15 ` [PATCH v5 05/27] KVM: x86: Suppress code #DBs on Intel if MOV/POP SS blocking is active Sean Christopherson
2022-08-30 23:15 ` [PATCH v5 06/27] KVM: nVMX: Treat General Detect #DB (DR7.GD=1) as fault-like Sean Christopherson
2022-08-30 23:15 ` Sean Christopherson [this message]
2022-08-30 23:15 ` [PATCH v5 08/27] KVM: x86: Treat #DBs from the emulator as fault-like (code and DR7.GD=1) Sean Christopherson
2022-08-30 23:15 ` [PATCH v5 09/27] KVM: x86: Use DR7_GD macro instead of open coding check in emulator Sean Christopherson
2022-08-30 23:15 ` [PATCH v5 10/27] KVM: nVMX: Ignore SIPI that arrives in L2 when vCPU is not in WFS Sean Christopherson
2022-08-30 23:15 ` [PATCH v5 11/27] KVM: nVMX: Unconditionally clear mtf_pending on nested VM-Exit Sean Christopherson
2022-08-30 23:15 ` [PATCH v5 12/27] KVM: VMX: Inject #PF on ENCLS as "emulated" #PF Sean Christopherson
2022-08-30 23:16 ` [PATCH v5 13/27] KVM: x86: Rename kvm_x86_ops.queue_exception to inject_exception Sean Christopherson
2022-08-30 23:16 ` [PATCH v5 14/27] KVM: x86: Make kvm_queued_exception a properly named, visible struct Sean Christopherson
2022-08-30 23:16 ` [PATCH v5 15/27] KVM: x86: Formalize blocking of nested pending exceptions Sean Christopherson
2022-08-30 23:16 ` [PATCH v5 16/27] KVM: x86: Use kvm_queue_exception_e() to queue #DF Sean Christopherson
2022-08-30 23:16 ` [PATCH v5 17/27] KVM: x86: Hoist nested event checks above event injection logic Sean Christopherson
2022-08-30 23:16 ` [PATCH v5 18/27] KVM: x86: Evaluate ability to inject SMI/NMI/IRQ after potential VM-Exit Sean Christopherson
2022-08-30 23:16 ` [PATCH v5 19/27] KVM: nVMX: Add a helper to identify low-priority #DB traps Sean Christopherson
2022-08-30 23:16 ` [PATCH v5 20/27] KVM: nVMX: Document priority of all known events on Intel CPUs Sean Christopherson
2022-08-30 23:16 ` [PATCH v5 21/27] KVM: x86: Morph pending exceptions to pending VM-Exits at queue time Sean Christopherson
2022-08-30 23:16 ` [PATCH v5 22/27] KVM: x86: Treat pending TRIPLE_FAULT requests as pending exceptions Sean Christopherson
2022-08-30 23:16 ` [PATCH v5 23/27] KVM: VMX: Update MTF and ICEBP comments to document KVM's subtle behavior Sean Christopherson
2022-08-30 23:16 ` [PATCH v5 24/27] KVM: x86: Rename inject_pending_events() to kvm_check_and_inject_events() Sean Christopherson
2022-08-30 23:16 ` [PATCH v5 25/27] KVM: selftests: Use uapi header to get VMX and SVM exit reasons/codes Sean Christopherson
2022-08-30 23:16 ` [PATCH v5 26/27] KVM: selftests: Add an x86-only test to verify nested exception queueing Sean Christopherson
2022-08-30 23:16 ` [PATCH v5 27/27] KVM: x86: Allow force_emulation_prefix to be written without a reload Sean Christopherson
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