KVM: nVMX: Switch to vmcs01 to update APIC page on-demand if L2 is active

If the KVM-owned APIC-access page is migrated while L2 is running,
temporarily load vmcs01 and immediately update APIC_ACCESS_ADDR instead
of deferring the update until the next nested VM-Exit.  Once changing
the virtual APIC mode is converted to always do on-demand updates, all
of the "defer until vmcs01 is active" logic will be gone.

Reviewed-by: Chao Gao <chao.gao@intel.com>
Link: https://patch.msgid.link/20260109034532.1012993-7-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index b141bc1fb247654d67e787a3285b8abab725f92c..9354d2017fd9de9841904d4585f0e49b7cdb303e 100644 (file)
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -5129,11 +5129,6 @@ void __nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 vm_exit_reason,
 
        nested_put_vmcs12_pages(vcpu);
 
-       if (vmx->nested.reload_vmcs01_apic_access_page) {
-               vmx->nested.reload_vmcs01_apic_access_page = false;
-               kvm_make_request(KVM_REQ_APIC_PAGE_RELOAD, vcpu);
-       }
-
        if ((vm_exit_reason != -1) &&
            (enable_shadow_vmcs || nested_vmx_is_evmptr12_valid(vmx)))
                vmx->nested.need_vmcs12_to_shadow_sync = true;

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index e7bab908cf6cdf21e6ec9cd0be03785e1bb2eba4..a8ddf0266072b59e2fffa4aadb8e829fc2efa0e7 100644 (file)
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6904,11 +6904,8 @@ void vmx_set_apic_access_page_addr(struct kvm_vcpu *vcpu)
        kvm_pfn_t pfn;
        bool writable;
 
-       /* Defer reload until vmcs01 is the current VMCS. */
-       if (is_guest_mode(vcpu)) {
-               to_vmx(vcpu)->nested.reload_vmcs01_apic_access_page = true;
-               return;
-       }
+       /* Note, the VIRTUALIZE_APIC_ACCESSES check needs to query vmcs01. */
+       guard(vmx_vmcs01)(vcpu);
 
        if (!(secondary_exec_controls_get(to_vmx(vcpu)) &
            SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES))

diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index dfc9766a7fa3de3d64339ac02181148ca84364c9..078bc6fef7e644bb95d63834c23814bb4aefce97 100644 (file)
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -132,7 +132,6 @@ struct nested_vmx {
        bool vmcs02_initialized;
 
        bool change_vmcs01_virtual_apic_mode;
-       bool reload_vmcs01_apic_access_page;
 
        /*
         * Enlightened VMCS has been enabled. It does not mean that L1 has to