[PATCH 5.4 162/411] KVM: nVMX: Leave most VM-Exit info fields unmodified on failed VM-Entry

Greg Kroah-Hartman
2022-06-13T11:24:18Z

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