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@intel.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Link: https://lore.kernel.org/r/20241009181742.1128779-7-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
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