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KVM: nVMX: Immediately refresh APICv controls as needed on nested VM-Exit

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[ Upstream commit 29763138830916f46daaa50e83e7f4f907a3236b ]

If an APICv status updated was pended while L2 was active, immediately
refresh vmcs01's controls instead of pending KVM_REQ_APICV_UPDATE as
kvm_vcpu_update_apicv() only calls into vendor code if a change is
necessary.

E.g. if APICv is inhibited, and then activated while L2 is running:

  kvm_vcpu_update_apicv()
  |
  -> __kvm_vcpu_update_apicv()
     |
     -> apic->apicv_active = true
      |
      -> vmx_refresh_apicv_exec_ctrl()
         |
         -> vmx->nested.update_vmcs01_apicv_status = true
          |
          -> return

Then L2 exits to L1:

  __nested_vmx_vmexit()
  |
  -> kvm_make_request(KVM_REQ_APICV_UPDATE)

  vcpu_enter_guest(): KVM_REQ_APICV_UPDATE
  -> kvm_vcpu_update_apicv()
     |
     -> __kvm_vcpu_update_apicv()
        |
        -> return // because if (apic->apicv_active == activate)

Reported-by: Chao Gao <chao.gao@intel.com>
Closes: https://lore.kernel.org/all/aQ2jmnN8wUYVEawF@intel.com
Fixes: 7c69661e22 ("KVM: nVMX: Defer APICv updates while L2 is active until L1 is active")
Cc: stable@vger.kernel.org
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
[sean: write changelog]
Link: https://patch.msgid.link/20251205231913.441872-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
[ exported vmx_refresh_apicv_exec_ctrl() and added declaration in vmx.h ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Dongli Zhang
2025-12-31 10:05:34 -05:00
committed by Greg Kroah-Hartman
parent 2f3139eaae
commit 37304368a2
3 changed files with 3 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
arch/x86/kvm/vmx/nested.c
View File

@@ -4908,7 +4908,7 @@ void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 vm_exit_reason,
if (vmx->nested.update_vmcs01_apicv_status) {
vmx->nested.update_vmcs01_apicv_status = false;
kvm_make_request(KVM_REQ_APICV_UPDATE, vcpu);
vmx_refresh_apicv_exec_ctrl(vcpu);
}
if (vmx->nested.update_vmcs01_hwapic_isr) {

2
arch/x86/kvm/vmx/vmx.c
View File

@@ -4451,7 +4451,7 @@ static u32 vmx_vmexit_ctrl(void)
~(VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL | VM_EXIT_LOAD_IA32_EFER);
}
static void vmx_refresh_apicv_exec_ctrl(struct kvm_vcpu *vcpu)
void vmx_refresh_apicv_exec_ctrl(struct kvm_vcpu *vcpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);

1
arch/x86/kvm/vmx/vmx.h
View File

@@ -395,6 +395,7 @@ void __vmx_set_segment(struct kvm_vcpu *vcpu, struct kvm_segment *var, int seg);
u64 construct_eptp(struct kvm_vcpu *vcpu, hpa_t root_hpa, int root_level);
bool vmx_guest_inject_ac(struct kvm_vcpu *vcpu);
void vmx_refresh_apicv_exec_ctrl(struct kvm_vcpu *vcpu);
void vmx_update_exception_bitmap(struct kvm_vcpu *vcpu);
bool vmx_nmi_blocked(struct kvm_vcpu *vcpu);
bool __vmx_interrupt_blocked(struct kvm_vcpu *vcpu);