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

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Message-Id: <20210106105306.450602-3-mlevitsk@redhat.com>
Date:   Wed,  6 Jan 2021 12:53:06 +0200
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     kvm@...r.kernel.org
Cc:     Joerg Roedel <joro@...tes.org>, Wanpeng Li <wanpengli@...cent.com>,
        linux-kernel@...r.kernel.org (open list:X86 ARCHITECTURE (32-BIT AND
        64-BIT)),
        x86@...nel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)),
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Jim Mattson <jmattson@...gle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Maxim Levitsky <mlevitsk@...hat.com>
Subject: [PATCH 2/2] KVM: nVMX: 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/vmx/nested.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index e2f26564a12de..2ea0bb14f385f 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -2355,12 +2355,12 @@ static void prepare_vmcs02_early(struct vcpu_vmx *vmx, struct vmcs12 *vmcs12)
 	 * Interrupt/Exception Fields
 	 */
 	if (vmx->nested.nested_run_pending) {
-		vmcs_write32(VM_ENTRY_INTR_INFO_FIELD,
-			     vmcs12->vm_entry_intr_info_field);
-		vmcs_write32(VM_ENTRY_EXCEPTION_ERROR_CODE,
-			     vmcs12->vm_entry_exception_error_code);
-		vmcs_write32(VM_ENTRY_INSTRUCTION_LEN,
-			     vmcs12->vm_entry_instruction_len);
+		if ((vmcs12->vm_entry_intr_info_field & VECTORING_INFO_VALID_MASK))
+			vmx_process_injected_event(&vmx->vcpu,
+						   vmcs12->vm_entry_intr_info_field,
+						   vmcs12->vm_entry_instruction_len,
+						   vmcs12->vm_entry_exception_error_code);
+
 		vmcs_write32(GUEST_INTERRUPTIBILITY_INFO,
 			     vmcs12->guest_interruptibility_info);
 		vmx->loaded_vmcs->nmi_known_unmasked =
-- 
2.26.2