This is a note to let you know that I've just added the patch titled
KVM: nVMX: Add a helper to identify low-priority #DB traps
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-add-a-helper-to-identify-low-priority-db-tr.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.
commit a5026653be6ccf7dff187ec87d628ef4ba5d89c5
Author: Sean Christopherson <seanjc@xxxxxxxxxx>
Date: Tue Aug 30 23:16:06 2022 +0000
KVM: nVMX: Add a helper to identify low-priority #DB traps
[ Upstream commit 2b384165f4d15540f94998b751f50058642ad110 ]
Add a helper to identify "low"-priority #DB traps, i.e. trap-like #DBs
that aren't TSS T flag #DBs, and tweak the related code to operate on any
queued exception. A future commit will separate exceptions that are
intercepted by L1, i.e. cause nested VM-Exit, from those that do NOT
trigger nested VM-Exit. I.e. there will be multiple exception structs
and multiple invocations of the helpers.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Reviewed-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20220830231614.3580124-20-seanjc@xxxxxxxxxx
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Stable-dep-of: 7709aba8f716 ("KVM: x86: Morph pending exceptions to pending VM-Exits at queue time")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 7655b5acbbcd..dfd5e13e5202 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -3871,14 +3871,24 @@ static void nested_vmx_inject_exception_vmexit(struct kvm_vcpu *vcpu,
* from the emulator (because such #DBs are fault-like and thus don't trigger
* actions that fire on instruction retire).
*/
-static inline unsigned long vmx_get_pending_dbg_trap(struct kvm_vcpu *vcpu)
+static unsigned long vmx_get_pending_dbg_trap(struct kvm_queued_exception *ex)
{
- if (!vcpu->arch.exception.pending ||
- vcpu->arch.exception.vector != DB_VECTOR)
+ if (!ex->pending || ex->vector != DB_VECTOR)
return 0;
/* General Detect #DBs are always fault-like. */
- return vcpu->arch.exception.payload & ~DR6_BD;
+ return ex->payload & ~DR6_BD;
+}
+
+/*
+ * Returns true if there's a pending #DB exception that is lower priority than
+ * a pending Monitor Trap Flag VM-Exit. TSS T-flag #DBs are not emulated by
+ * KVM, but could theoretically be injected by userspace. Note, this code is
+ * imperfect, see above.
+ */
+static bool vmx_is_low_priority_db_trap(struct kvm_queued_exception *ex)
+{
+ return vmx_get_pending_dbg_trap(ex) & ~DR6_BT;
}
/*
@@ -3890,8 +3900,9 @@ static inline unsigned long vmx_get_pending_dbg_trap(struct kvm_vcpu *vcpu)
*/
static void nested_vmx_update_pending_dbg(struct kvm_vcpu *vcpu)
{
- unsigned long pending_dbg = vmx_get_pending_dbg_trap(vcpu);
+ unsigned long pending_dbg;
+ pending_dbg = vmx_get_pending_dbg_trap(&vcpu->arch.exception);
if (pending_dbg)
vmcs_writel(GUEST_PENDING_DBG_EXCEPTIONS, pending_dbg);
}
@@ -3961,7 +3972,7 @@ static int vmx_check_nested_events(struct kvm_vcpu *vcpu)
* prioritize SMI over MTF and trap-like #DBs.
*/
if (vcpu->arch.exception.pending &&
- !(vmx_get_pending_dbg_trap(vcpu) & ~DR6_BT)) {
+ !vmx_is_low_priority_db_trap(&vcpu->arch.exception)) {
if (block_nested_exceptions)
return -EBUSY;
if (!nested_vmx_check_exception(vcpu, &exit_qual))
