[PATCH 17/43] KVM: x86: Open code necessary bits of kvm_lapic_set_base() at vCPU RESET

From: Sean Christopherson
Date: Fri Apr 23 2021 - 20:50:53 EST


Stuff vcpu->arch.apic_base and apic->base_address directly during APIC
reset, as opposed to bouncing through kvm_set_apic_base() while fudging
the ENABLE bit during creation to avoid the other, unwanted side effects.

This is a step towards consolidating the APIC RESET logic across x86,
VMX, and SVM.

Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/kvm/lapic.c | 15 ++++++---------
1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index b088f6984b37..b1366df46d1d 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -2305,7 +2305,6 @@ EXPORT_SYMBOL_GPL(kvm_apic_update_apicv);
void kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event)
{
struct kvm_lapic *apic = vcpu->arch.apic;
- u64 msr_val;
int i;

if (!apic)
@@ -2315,10 +2314,13 @@ void kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event)
hrtimer_cancel(&apic->lapic_timer.timer);

if (!init_event) {
- msr_val = APIC_DEFAULT_PHYS_BASE | MSR_IA32_APICBASE_ENABLE;
+ vcpu->arch.apic_base = APIC_DEFAULT_PHYS_BASE |
+ MSR_IA32_APICBASE_ENABLE;
if (kvm_vcpu_is_reset_bsp(vcpu))
- msr_val |= MSR_IA32_APICBASE_BSP;
- kvm_lapic_set_base(vcpu, msr_val);
+ vcpu->arch.apic_base |= MSR_IA32_APICBASE_BSP;
+
+ apic->base_address = MSR_IA32_APICBASE_ENABLE;
+
kvm_apic_set_xapic_id(apic, vcpu->vcpu_id);
}
kvm_apic_set_version(apic->vcpu);
@@ -2461,11 +2463,6 @@ int kvm_create_lapic(struct kvm_vcpu *vcpu, int timer_advance_ns)
lapic_timer_advance_dynamic = false;
}

- /*
- * APIC is created enabled. This will prevent kvm_lapic_set_base from
- * thinking that APIC state has changed.
- */
- vcpu->arch.apic_base = MSR_IA32_APICBASE_ENABLE;
static_branch_inc(&apic_sw_disabled.key); /* sw disabled at reset */
kvm_iodevice_init(&apic->dev, &apic_mmio_ops);

--
2.31.1.498.g6c1eba8ee3d-goog