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KVM: nVMX: Use vmcs01's controls shadow to check for IRQ/NMI windows at VM-Enter

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Use vmcs01's execution controls shadow to check for IRQ/NMI windows after
a successful nested VM-Enter, instead of snapshotting the information prior
to emulating VM-Enter.  It's quite difficult to see that the entire reason
controls are snapshot prior nested VM-Enter is to read them from vmcs01
(vmcs02 is loaded if nested VM-Enter is successful).

That could be solved with a comment, but explicitly using vmcs01's shadow
makes the code self-documenting to a certain extent.

No functional change intended (vmcs01's execution controls must not be
modified during emulation of nested VM-Enter).

Link: https://lore.kernel.org/r/20241101191447.1807602-5-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson 2024-11-01 12:14:46 -07:00
parent b2868b55cf
commit c829d2c356
1 changed files with 4 additions and 6 deletions
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10
arch/x86/kvm/vmx/nested.c
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@ -3500,7 +3500,6 @@ enum nvmx_vmentry_status nested_vmx_enter_non_root_mode(struct kvm_vcpu *vcpu,
struct vcpu_vmx *vmx = to_vmx(vcpu);
struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
enum vm_entry_failure_code entry_failure_code;
bool evaluate_pending_interrupts;
union vmx_exit_reason exit_reason = {
.basic = EXIT_REASON_INVALID_STATE,
.failed_vmentry = 1,
@ -3519,9 +3518,6 @@ enum nvmx_vmentry_status nested_vmx_enter_non_root_mode(struct kvm_vcpu *vcpu,
kvm_service_local_tlb_flush_requests(vcpu);
evaluate_pending_interrupts = exec_controls_get(vmx) &
(CPU_BASED_INTR_WINDOW_EXITING | CPU_BASED_NMI_WINDOW_EXITING);
if (!vmx->nested.nested_run_pending ||
!(vmcs12->vm_entry_controls & VM_ENTRY_LOAD_DEBUG_CONTROLS))
vmx->nested.pre_vmenter_debugctl = vmcs_read64(GUEST_IA32_DEBUGCTL);
@ -3604,9 +3600,11 @@ enum nvmx_vmentry_status nested_vmx_enter_non_root_mode(struct kvm_vcpu *vcpu,
* Re-evaluate pending events if L1 had a pending IRQ/NMI/INIT/SIPI
* when it executed VMLAUNCH/VMRESUME, as entering non-root mode can
* effectively unblock various events, e.g. INIT/SIPI cause VM-Exit
* unconditionally.
* unconditionally. Take care to pull data from vmcs01 as appropriate,
* e.g. when checking for interrupt windows, as vmcs02 is now loaded.
*/
if (unlikely(evaluate_pending_interrupts) ||
if ((__exec_controls_get(&vmx->vmcs01) & (CPU_BASED_INTR_WINDOW_EXITING |
CPU_BASED_NMI_WINDOW_EXITING)) ||
kvm_apic_has_pending_init_or_sipi(vcpu) ||
kvm_apic_has_interrupt(vcpu))
kvm_make_request(KVM_REQ_EVENT, vcpu);