releases/5.4.198/kvm-nvmx-leave-most-vm-exit-info-fields-unmodified-o.patch

From 52066136260bcdd04e3132bb453119e285769071 Mon Sep 17 00:00:00 2001
From: Sasha Levin <sashal@kernel.org>
Date: Thu, 7 Apr 2022 00:23:14 +0000
Subject: KVM: nVMX: Leave most VM-Exit info fields unmodified on failed
 VM-Entry

From: Sean Christopherson <seanjc@google.com>

[ Upstream commit c3634d25fbee88e2368a8e0903ae0d0670eb9e71 ]

Don't modify vmcs12 exit fields except EXIT_REASON and EXIT_QUALIFICATION
when performing a nested VM-Exit due to failed VM-Entry.  Per the SDM,
only the two aformentioned fields are filled and "All other VM-exit
information fields are unmodified".

Fixes: 4704d0befb07 ("KVM: nVMX: Exiting from L2 to L1")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220407002315.78092-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/x86/kvm/vmx/nested.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 3041015b05f7..9f61ae64b727 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -3746,12 +3746,12 @@ static void prepare_vmcs12(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
 	/* update exit information fields: */
 	vmcs12->vm_exit_reason = exit_reason;
 	vmcs12->exit_qualification = exit_qualification;
-	vmcs12->vm_exit_intr_info = exit_intr_info;
-
-	vmcs12->idt_vectoring_info_field = 0;
-	vmcs12->vm_exit_instruction_len = vmcs_read32(VM_EXIT_INSTRUCTION_LEN);
-	vmcs12->vmx_instruction_info = vmcs_read32(VMX_INSTRUCTION_INFO);
 
+	/*
+	 * On VM-Exit due to a failed VM-Entry, the VMCS isn't marked launched
+	 * and only EXIT_REASON and EXIT_QUALIFICATION are updated, all other
+	 * exit info fields are unmodified.
+	 */
 	if (!(vmcs12->vm_exit_reason & VMX_EXIT_REASONS_FAILED_VMENTRY)) {
 		vmcs12->launch_state = 1;
 
@@ -3763,8 +3763,13 @@ static void prepare_vmcs12(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
 		 * Transfer the event that L0 or L1 may wanted to inject into
 		 * L2 to IDT_VECTORING_INFO_FIELD.
 		 */
+		vmcs12->idt_vectoring_info_field = 0;
 		vmcs12_save_pending_event(vcpu, vmcs12);
 
+		vmcs12->vm_exit_intr_info = exit_intr_info;
+		vmcs12->vm_exit_instruction_len = vmcs_read32(VM_EXIT_INSTRUCTION_LEN);
+		vmcs12->vmx_instruction_info = vmcs_read32(VMX_INSTRUCTION_INFO);
+
 		/*
 		 * According to spec, there's no need to store the guest's
 		 * MSRs if the exit is due to a VM-entry failure that occurs
-- 
2.35.1