The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From de7cd3f6761f49bef044ec49493d88737a70f1a6 Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Date: Wed, 20 Oct 2021 06:27:36 -0400
Subject: [PATCH] KVM: x86: check for interrupts before deciding whether to
exit the fast path
The kvm_x86_sync_pir_to_irr callback can sometimes set KVM_REQ_EVENT.
If that happens exactly at the time that an exit is handled as
EXIT_FASTPATH_REENTER_GUEST, vcpu_enter_guest will go incorrectly
through the loop that calls kvm_x86_run, instead of processing
the request promptly.
Fixes: 379a3c8ee444 ("KVM: VMX: Optimize posted-interrupt delivery for timer fastpath")
Cc: stable@xxxxxxxxxxxxxxx
Reviewed-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 0c8b5129effd..381384a54790 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9643,14 +9643,14 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
if (likely(exit_fastpath != EXIT_FASTPATH_REENTER_GUEST))
break;
- if (unlikely(kvm_vcpu_exit_request(vcpu))) {
+ if (vcpu->arch.apicv_active)
+ static_call(kvm_x86_sync_pir_to_irr)(vcpu);
+
+ if (unlikely(kvm_vcpu_exit_request(vcpu))) {
exit_fastpath = EXIT_FASTPATH_EXIT_HANDLED;
break;
}
-
- if (vcpu->arch.apicv_active)
- static_call(kvm_x86_sync_pir_to_irr)(vcpu);
- }
+ }
/*
* Do this here before restoring debug registers on the host. And
