SDM April 2015, 10.12.5 State Changes From xAPIC Mode to x2APIC Mode
• Any APIC ID value written to the memory-mapped local APIC ID register
is not preserved.
Fix it by sourcing vcpu_id (= initial APIC ID) instead of memory-mapped
APIC ID. Proper use of apic functions would result in two calls to
recalculate_apic_map(), so this patch makes a new helper.
Signed-off-by: Radim Krčmář <rkrcmar@xxxxxxxxxx>
---
arch/x86/kvm/lapic.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index dc5b57bb1f76..c2a7d8a7a414 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -240,6 +240,15 @@ static inline void kvm_apic_set_ldr(struct kvm_lapic *apic, u32 id)
recalculate_apic_map(apic->vcpu->kvm);
}
+static inline void kvm_apic_set_x2apic_id(struct kvm_lapic *apic, u8 id)
+{
+ u32 ldr = ((id >> 4) << 16) | (1 << (id & 0xf));
+
+ apic_set_reg(apic, APIC_ID, id << 24);
+ apic_set_reg(apic, APIC_LDR, ldr);
+ recalculate_apic_map(apic->vcpu->kvm);
+}
+
static inline int apic_lvt_enabled(struct kvm_lapic *apic, int lvt_type)
{
return !(kvm_apic_get_reg(apic, lvt_type) & APIC_LVT_MASKED);
@@ -1538,9 +1547,7 @@ void kvm_lapic_set_base(struct kvm_vcpu *vcpu, u64 value)
if ((old_value ^ value) & X2APIC_ENABLE) {
if (value & X2APIC_ENABLE) {
- u32 id = kvm_apic_id(apic);
- u32 ldr = ((id >> 4) << 16) | (1 << (id & 0xf));
- kvm_apic_set_ldr(apic, ldr);
+ kvm_apic_set_x2apic_id(apic, vcpu->vcpu_id);
kvm_x86_ops->set_virtual_x2apic_mode(vcpu, true);
} else
kvm_x86_ops->set_virtual_x2apic_mode(vcpu, false);
--
2.4.1
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