linux-kernel - [PATCH 2/6] KVM: nSVM: fix for disappearing L1->L2 event injection on L1 migration

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Message-Id: <20210106105001.449974-3-mlevitsk@redhat.com>
Date:   Wed,  6 Jan 2021 12:49:57 +0200
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     kvm@...r.kernel.org
Cc:     Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        linux-kernel@...r.kernel.org (open list:X86 ARCHITECTURE (32-BIT AND
        64-BIT)), Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        x86@...nel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)),
        Wanpeng Li <wanpengli@...cent.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Borislav Petkov <bp@...en8.de>,
        Maxim Levitsky <mlevitsk@...hat.com>
Subject: [PATCH 2/6] KVM: nSVM: fix for disappearing L1->L2 event injection on L1 migration

If migration happens while L2 entry with an injected event to L2 is pending,
we weren't including the event in the migration state and it would be
lost leading to L2 hang.

Fix this by queueing the injected event in similar manner to how we queue
interrupted injections.

This can be reproduced by running an IO intense task in L2,
and repeatedly migrating the L1.

Suggested-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Maxim Levitsky <mlevitsk@...hat.com>
---
 arch/x86/kvm/svm/nested.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index b0b667456b2e7..18b71e73a9935 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -416,8 +416,11 @@ static void nested_prepare_vmcb_control(struct vcpu_svm *svm)
 	svm->vmcb->control.virt_ext            = svm->nested.ctl.virt_ext;
 	svm->vmcb->control.int_vector          = svm->nested.ctl.int_vector;
 	svm->vmcb->control.int_state           = svm->nested.ctl.int_state;
-	svm->vmcb->control.event_inj           = svm->nested.ctl.event_inj;
-	svm->vmcb->control.event_inj_err       = svm->nested.ctl.event_inj_err;
+
+	svm_process_injected_event(svm, svm->nested.ctl.event_inj,
+				   svm->nested.ctl.event_inj_err);
+
+	WARN_ON_ONCE(svm->vmcb->control.event_inj);
 
 	svm->vmcb->control.pause_filter_count  = svm->nested.ctl.pause_filter_count;
 	svm->vmcb->control.pause_filter_thresh = svm->nested.ctl.pause_filter_thresh;
-- 
2.26.2