This is a note to let you know that I've just added the patch titled
KVM: nVMX: Unconditionally purge queued/injected events on nested "exit"
to the 6.0-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-unconditionally-purge-queued-injected-events-on-nested-exit.patch
and it can be found in the queue-6.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From d953540430c5af57f5de97ea9e36253908204027 Mon Sep 17 00:00:00 2001
From: Sean Christopherson <seanjc@xxxxxxxxxx>
Date: Tue, 30 Aug 2022 23:15:48 +0000
Subject: KVM: nVMX: Unconditionally purge queued/injected events on nested "exit"
From: Sean Christopherson <seanjc@xxxxxxxxxx>
commit d953540430c5af57f5de97ea9e36253908204027 upstream.
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@xxxxxxxxxxxxxxx
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Reviewed-by: Jim Mattson <jmattson@xxxxxxxxxx>
Reviewed-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20220830231614.3580124-2-seanjc@xxxxxxxxxx
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/vmx/nested.c | 19 +++++++++++--------
1 file changed, 11 insertions(+), 8 deletions(-)
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -4255,14 +4255,6 @@ static void prepare_vmcs12(struct kvm_vc
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);
}
/*
@@ -4602,6 +4594,17 @@ void nested_vmx_vmexit(struct kvm_vcpu *
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 */
Patches currently in stable-queue which might be from seanjc@xxxxxxxxxx are
queue-6.0/kvm-nvmx-unconditionally-purge-queued-injected-events-on-nested-exit.patch
queue-6.0/kvm-vmx-drop-bits-31-16-when-shoving-exception-error-code-into-vmcs.patch
queue-6.0/kvm-nvmx-don-t-propagate-vmcs12-s-perf_global_ctrl-settings-to-vmcs02.patch
queue-6.0/kvm-x86-emulator-fix-handing-of-pop-ss-to-correctly-set-interruptibility.patch
queue-6.0/kvm-x86-treat-dbs-from-the-emulator-as-fault-like-code-and-dr7.gd-1.patch
