This is a note to let you know that I've just added the patch titled
KVM: nVMX: Prioritize TSS T-flag #DBs over Monitor Trap Flag
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-nvmx-prioritize-tss-t-flag-dbs-over-monitor-trap.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit c09b39bc2c9bfd8e2bdf4966c48c353b4e4a5127
Author: Sean Christopherson <seanjc@xxxxxxxxxx>
Date: Tue Aug 30 23:15:54 2022 +0000
KVM: nVMX: Prioritize TSS T-flag #DBs over Monitor Trap Flag
[ Upstream commit b9d44f9091ac6c325fc2f7b7671b462fb36abbed ]
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@xxxxxxxxxx>
Cc: Peter Shier <pshier@xxxxxxxxxx>
Fixes: 5ef8acbdd687 ("KVM: nVMX: Emulate MTF when performing instruction emulation")
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Reviewed-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20220830231614.3580124-8-seanjc@xxxxxxxxxx
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index cdbe827ec960..f28085b89f47 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -3938,15 +3938,17 @@ 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))
