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    Subject[PATCH 02/19] KVM: SVM: Don't put/load AVIC when setting virtual APIC mode
    From
    Move the VMCB updates from avic_refresh_apicv_exec_ctrl() into
    avic_set_virtual_apic_mode() and invert the dependency being said
    functions to avoid calling avic_vcpu_{load,put}() and
    avic_set_pi_irte_mode() when "only" setting the virtual APIC mode.

    avic_set_virtual_apic_mode() is invoked from common x86 with preemption
    enabled, which makes avic_vcpu_{load,put}() unhappy. Luckily, calling
    those and updating IRTE stuff is unnecessary as the only reason
    avic_set_virtual_apic_mode() is called is to handle transitions between
    xAPIC and x2APIC that don't also toggle APICv activation. And if
    activation doesn't change, there's no need to fiddle with the physical
    APIC ID table or update IRTE.

    The "full" refresh is guaranteed to be called if activation changes in
    this case as the only call to the "set" path is:

    kvm_vcpu_update_apicv(vcpu);
    static_call_cond(kvm_x86_set_virtual_apic_mode)(vcpu);

    and kvm_vcpu_update_apicv() invokes the refresh if activation changes:

    if (apic->apicv_active == activate)
    goto out;

    apic->apicv_active = activate;
    kvm_apic_update_apicv(vcpu);
    static_call(kvm_x86_refresh_apicv_exec_ctrl)(vcpu);

    WARNING: CPU: 183 PID: 49186 at arch/x86/kvm/svm/avic.c:1081 avic_vcpu_put+0xde/0xf0 [kvm_amd]
    CPU: 183 PID: 49186 Comm: stable Tainted: G O 6.0.0-smp--fcddbca45f0a-sink #34
    Hardware name: Google, Inc. Arcadia_IT_80/Arcadia_IT_80, BIOS 10.48.0 01/27/2022
    RIP: 0010:avic_vcpu_put+0xde/0xf0 [kvm_amd]
    avic_refresh_apicv_exec_ctrl+0x142/0x1c0 [kvm_amd]
    avic_set_virtual_apic_mode+0x5a/0x70 [kvm_amd]
    kvm_lapic_set_base+0x149/0x1a0 [kvm]
    kvm_set_apic_base+0x8f/0xd0 [kvm]
    kvm_set_msr_common+0xa3a/0xdc0 [kvm]
    svm_set_msr+0x364/0x6b0 [kvm_amd]
    __kvm_set_msr+0xb8/0x1c0 [kvm]
    kvm_emulate_wrmsr+0x58/0x1d0 [kvm]
    msr_interception+0x1c/0x30 [kvm_amd]
    svm_invoke_exit_handler+0x31/0x100 [kvm_amd]
    svm_handle_exit+0xfc/0x160 [kvm_amd]
    vcpu_enter_guest+0x21bb/0x23e0 [kvm]
    vcpu_run+0x92/0x450 [kvm]
    kvm_arch_vcpu_ioctl_run+0x43e/0x6e0 [kvm]
    kvm_vcpu_ioctl+0x559/0x620 [kvm]

    Fixes: 05c4fe8c1bd9 ("KVM: SVM: Refresh AVIC configuration when changing APIC mode")
    Cc: stable@vger.kernel.org
    Cc: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
    Cc: Maxim Levitsky <mlevitsk@redhat.com>
    Signed-off-by: Sean Christopherson <seanjc@google.com>
    ---
    arch/x86/kvm/svm/avic.c | 31 +++++++++++++++----------------
    1 file changed, 15 insertions(+), 16 deletions(-)

    diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
    index b1ade555e8d0..f3a74c8284cb 100644
    --- a/arch/x86/kvm/svm/avic.c
    +++ b/arch/x86/kvm/svm/avic.c
    @@ -741,18 +741,6 @@ void avic_apicv_post_state_restore(struct kvm_vcpu *vcpu)
    avic_handle_ldr_update(vcpu);
    }

    -void avic_set_virtual_apic_mode(struct kvm_vcpu *vcpu)
    -{
    - if (!lapic_in_kernel(vcpu) || avic_mode == AVIC_MODE_NONE)
    - return;
    -
    - if (kvm_get_apic_mode(vcpu) == LAPIC_MODE_INVALID) {
    - WARN_ONCE(true, "Invalid local APIC state (vcpu_id=%d)", vcpu->vcpu_id);
    - return;
    - }
    - avic_refresh_apicv_exec_ctrl(vcpu);
    -}
    -
    static int avic_set_pi_irte_mode(struct kvm_vcpu *vcpu, bool activate)
    {
    int ret = 0;
    @@ -1094,17 +1082,18 @@ void avic_vcpu_put(struct kvm_vcpu *vcpu)
    WRITE_ONCE(*(svm->avic_physical_id_cache), entry);
    }

    -
    -void avic_refresh_apicv_exec_ctrl(struct kvm_vcpu *vcpu)
    +void avic_set_virtual_apic_mode(struct kvm_vcpu *vcpu)
    {
    struct vcpu_svm *svm = to_svm(vcpu);
    struct vmcb *vmcb = svm->vmcb01.ptr;
    - bool activated = kvm_vcpu_apicv_active(vcpu);
    +
    + if (!lapic_in_kernel(vcpu) || avic_mode == AVIC_MODE_NONE)
    + return;

    if (!enable_apicv)
    return;

    - if (activated) {
    + if (kvm_vcpu_apicv_active(vcpu)) {
    /**
    * During AVIC temporary deactivation, guest could update
    * APIC ID, DFR and LDR registers, which would not be trapped
    @@ -1118,6 +1107,16 @@ void avic_refresh_apicv_exec_ctrl(struct kvm_vcpu *vcpu)
    avic_deactivate_vmcb(svm);
    }
    vmcb_mark_dirty(vmcb, VMCB_AVIC);
    +}
    +
    +void avic_refresh_apicv_exec_ctrl(struct kvm_vcpu *vcpu)
    +{
    + bool activated = kvm_vcpu_apicv_active(vcpu);
    +
    + if (!enable_apicv)
    + return;
    +
    + avic_set_virtual_apic_mode(vcpu);

    if (activated)
    avic_vcpu_load(vcpu, vcpu->cpu);
    --
    2.37.2.672.g94769d06f0-goog
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