Rename kvm_set_apic_base() and kvm_lapic_set_base() to kvm_apic_set_base() and __kvm_apic_set_base() respectively to capture that the underscores version is a "special" variant (it exists purely to avoid recalculating the optimized map multiple times when stuffing the RESET value). Opportunistically add a comment explaining why kvm_lapic_reset() uses the inner helper. Note, KVM deliberately invokes kvm_arch_vcpu_create() while kvm->lock is NOT held so that vCPU setup isn't serialized if userspace is creating multiple/all vCPUs in parallel. I.e. triggering an extra recalculation is not limited to theoretical/rare edge cases, and so is worth avoiding. No functional change intended. Reviewed-by: Kai Huang <kai.huang@xxxxxxxxx> Reviewed-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> Link: https://lore.kernel.org/r/20241009181742.1128779-7-seanjc@xxxxxxxxxx Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx> --- arch/x86/kvm/lapic.c | 15 +++++++++++---- arch/x86/kvm/lapic.h | 3 +-- arch/x86/kvm/x86.c | 4 ++-- 3 files changed, 14 insertions(+), 8 deletions(-) diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index b4cc5b0e8796..0472a94e7b3b 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -2577,7 +2577,7 @@ u64 kvm_lapic_get_cr8(struct kvm_vcpu *vcpu) return (tpr & 0xf0) >> 4; } -void kvm_lapic_set_base(struct kvm_vcpu *vcpu, u64 value) +static void __kvm_apic_set_base(struct kvm_vcpu *vcpu, u64 value) { u64 old_value = vcpu->arch.apic_base; struct kvm_lapic *apic = vcpu->arch.apic; @@ -2628,7 +2628,7 @@ void kvm_lapic_set_base(struct kvm_vcpu *vcpu, u64 value) } } -int kvm_set_apic_base(struct kvm_vcpu *vcpu, struct msr_data *msr_info) +int kvm_apic_set_base(struct kvm_vcpu *vcpu, struct msr_data *msr_info) { enum lapic_mode old_mode = kvm_get_apic_mode(vcpu); enum lapic_mode new_mode = kvm_apic_mode(msr_info->data); @@ -2644,7 +2644,7 @@ int kvm_set_apic_base(struct kvm_vcpu *vcpu, struct msr_data *msr_info) return 1; } - kvm_lapic_set_base(vcpu, msr_info->data); + __kvm_apic_set_base(vcpu, msr_info->data); kvm_recalculate_apic_map(vcpu->kvm); return 0; } @@ -2740,7 +2740,14 @@ void kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event) msr_val = 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); + + /* + * Use the inner helper to avoid an extra recalcuation of the + * optimized APIC map if some other task has dirtied the map. + * The recalculation needed for this vCPU will be done after + * all APIC state has been initialized (see below). + */ + __kvm_apic_set_base(vcpu, msr_val); } if (!apic) diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h index fc4bd36d44cf..0dd5055852ad 100644 --- a/arch/x86/kvm/lapic.h +++ b/arch/x86/kvm/lapic.h @@ -95,7 +95,6 @@ void kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event); u64 kvm_lapic_get_cr8(struct kvm_vcpu *vcpu); void kvm_lapic_set_tpr(struct kvm_vcpu *vcpu, unsigned long cr8); void kvm_lapic_set_eoi(struct kvm_vcpu *vcpu); -void kvm_lapic_set_base(struct kvm_vcpu *vcpu, u64 value); void kvm_recalculate_apic_map(struct kvm *kvm); void kvm_apic_set_version(struct kvm_vcpu *vcpu); void kvm_apic_after_set_mcg_cap(struct kvm_vcpu *vcpu); @@ -117,7 +116,7 @@ bool kvm_irq_delivery_to_apic_fast(struct kvm *kvm, struct kvm_lapic *src, struct kvm_lapic_irq *irq, int *r, struct dest_map *dest_map); void kvm_apic_send_ipi(struct kvm_lapic *apic, u32 icr_low, u32 icr_high); -int kvm_set_apic_base(struct kvm_vcpu *vcpu, struct msr_data *msr_info); +int kvm_apic_set_base(struct kvm_vcpu *vcpu, struct msr_data *msr_info); int kvm_apic_get_state(struct kvm_vcpu *vcpu, struct kvm_lapic_state *s); int kvm_apic_set_state(struct kvm_vcpu *vcpu, struct kvm_lapic_state *s); int kvm_lapic_find_highest_irr(struct kvm_vcpu *vcpu); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 57dca2bdd40d..e01188dc82d1 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3863,7 +3863,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) case MSR_MTRRdefType: return kvm_mtrr_set_msr(vcpu, msr, data); case MSR_IA32_APICBASE: - return kvm_set_apic_base(vcpu, msr_info); + return kvm_apic_set_base(vcpu, msr_info); case APIC_BASE_MSR ... APIC_BASE_MSR + 0xff: return kvm_x2apic_msr_write(vcpu, msr, data); case MSR_IA32_TSC_DEADLINE: @@ -11879,7 +11879,7 @@ static int __set_sregs_common(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs, apic_base_msr.data = sregs->apic_base; apic_base_msr.host_initiated = true; - if (kvm_set_apic_base(vcpu, &apic_base_msr)) + if (kvm_apic_set_base(vcpu, &apic_base_msr)) return -EINVAL; if (vcpu->arch.guest_state_protected) -- 2.47.0.163.g1226f6d8fa-goog
