[PATCH v1 06/11] KVM: x86: use hardware-compatible format for APIC ID register

Radim Krčmář
2016-06-30T20:55:52Z

We currently always shift APIC ID as if APIC was in xAPIC mode.
x2APIC mode wants to use more bits and storing a hardware-compabible
value is the the sanest option.

KVM API to set the lapic expects that bottom 8 bits of APIC ID are in
top 8 bits of APIC_ID register, so the register needs to be shifted in
x2APIC mode.

Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
---
v1:
* drop big endian format in lapic get/set ioctl [Paolo]
* exclude APICv optimization of APIC ID register
* rename __kvm_apic_state_fixup() parameter from 'restore' to 'set'

arch/x86/kvm/lapic.c | 44 ++++++++++++++++++++++++++++++++------------
arch/x86/kvm/lapic.h | 7 ++++++-
arch/x86/kvm/x86.c | 2 ++
3 files changed, 40 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 4296bb7353ff..d914b5351fdc 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -224,7 +224,7 @@ static inline void apic_set_spiv(struct kvm_lapic *apic, u32 val)
}
}

-static inline void kvm_apic_set_id(struct kvm_lapic *apic, u8 id)
+static inline void kvm_apic_set_xapic_id(struct kvm_lapic *apic, u8 id)
{
kvm_lapic_set_reg(apic, APIC_ID, id << 24);
recalculate_apic_map(apic->vcpu->kvm);
@@ -236,11 +236,11 @@ 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)
+static inline void kvm_apic_set_x2apic_id(struct kvm_lapic *apic, u32 id)
{
u32 ldr = ((id >> 4) << 16) | (1 << (id & 0xf));

- kvm_lapic_set_reg(apic, APIC_ID, id << 24);
+ kvm_lapic_set_reg(apic, APIC_ID, id);
kvm_lapic_set_reg(apic, APIC_LDR, ldr);
recalculate_apic_map(apic->vcpu->kvm);
}
@@ -1096,12 +1096,6 @@ static u32 __apic_read(struct kvm_lapic *apic, unsigned int offset)
return 0;

switch (offset) {
- case APIC_ID:
- if (apic_x2apic_mode(apic))
- val = kvm_apic_id(apic);
- else
- val = kvm_apic_id(apic) << 24;
- break;
case APIC_ARBPRI:
apic_debug("Access APIC ARBPRI register which is for P6\n");
break;
@@ -1459,7 +1453,7 @@ int kvm_lapic_reg_write(struct kvm_lapic *apic, u32 reg, u32 val)
switch (reg) {
case APIC_ID: /* Local APIC ID */
if (!apic_x2apic_mode(apic))
- kvm_apic_set_id(apic, val >> 24);
+ kvm_apic_set_xapic_id(apic, val >> 24);
else
ret = 1;
break;
@@ -1731,8 +1725,10 @@ void kvm_lapic_set_base(struct kvm_vcpu *vcpu, u64 value)
if (value & X2APIC_ENABLE) {
kvm_apic_set_x2apic_id(apic, vcpu->vcpu_id);
kvm_x86_ops->set_virtual_x2apic_mode(vcpu, true);
- } else
+ } else {
+ kvm_apic_set_xapic_id(apic, vcpu->vcpu_id);
kvm_x86_ops->set_virtual_x2apic_mode(vcpu, false);
+ }
}

apic->base_address = apic->vcpu->arch.apic_base &
@@ -1763,7 +1759,7 @@ void kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event)
hrtimer_cancel(&apic->lapic_timer.timer);

if (!init_event)
- kvm_apic_set_id(apic, vcpu->vcpu_id);
+ kvm_apic_set_xapic_id(apic, vcpu->vcpu_id);
kvm_apic_set_version(apic->vcpu);

for (i = 0; i < KVM_APIC_LVT_NUM; i++)
@@ -1984,6 +1980,30 @@ int kvm_get_apic_interrupt(struct kvm_vcpu *vcpu)
return vector;
}

+static void __kvm_apic_state_fixup(struct kvm_vcpu *vcpu,
+ struct kvm_lapic_state *s, bool set)
+{
+ if (apic_x2apic_mode(vcpu->arch.apic)) {
+ u32 *id = (u32 *)(s->regs + APIC_ID);
+ if (set)
+ *id >>= 24;
+ else
+ *id <<= 24;
+ }
+}
+
+void kvm_apic_state_get_fixup(struct kvm_vcpu *vcpu,
+ struct kvm_lapic_state *s)
+{
+ __kvm_apic_state_fixup(vcpu, s, false);
+}
+
+void kvm_apic_state_set_fixup(struct kvm_vcpu *vcpu,
+ struct kvm_lapic_state *s)
+{
+ __kvm_apic_state_fixup(vcpu, s, true);
+}
+
void kvm_apic_post_state_restore(struct kvm_vcpu *vcpu,
struct kvm_lapic_state *s)
{
diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index 8d811139d2b3..8d33cc56ee62 100644
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -81,6 +81,10 @@ bool kvm_irq_delivery_to_apic_fast(struct kvm *kvm, struct kvm_lapic *src,

u64 kvm_get_apic_base(struct kvm_vcpu *vcpu);
int kvm_set_apic_base(struct kvm_vcpu *vcpu, struct msr_data *msr_info);
+void kvm_apic_state_get_fixup(struct kvm_vcpu *vcpu,
+ struct kvm_lapic_state *s);
+void kvm_apic_state_set_fixup(struct kvm_vcpu *vcpu,
+ struct kvm_lapic_state *s);
void kvm_apic_post_state_restore(struct kvm_vcpu *vcpu,
struct kvm_lapic_state *s);
int kvm_lapic_find_highest_irr(struct kvm_vcpu *vcpu);
@@ -202,7 +206,8 @@ static inline int kvm_lapic_latched_init(struct kvm_vcpu *vcpu)

static inline u32 kvm_apic_id(struct kvm_lapic *apic)
{
- return (kvm_lapic_get_reg(apic, APIC_ID) >> 24) & 0xff;
+ u32 id = kvm_lapic_get_reg(apic, APIC_ID);
+ return apic_x2apic_mode(apic) ? id : id >> 24;
}

bool kvm_apic_pending_eoi(struct kvm_vcpu *vcpu, int vector);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 0cc6cf834cdd..043f110f2210 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2780,6 +2780,7 @@ static int kvm_vcpu_ioctl_get_lapic(struct kvm_vcpu *vcpu,
kvm_x86_ops->sync_pir_to_irr(vcpu);

memcpy(s->regs, vcpu->arch.apic->regs, sizeof *s);
+ kvm_apic_state_get_fixup(vcpu, s);

return 0;
}
@@ -2787,6 +2788,7 @@ static int kvm_vcpu_ioctl_get_lapic(struct kvm_vcpu *vcpu,
static int kvm_vcpu_ioctl_set_lapic(struct kvm_vcpu *vcpu,
struct kvm_lapic_state *s)
{
+ kvm_apic_state_set_fixup(vcpu, s);
kvm_apic_post_state_restore(vcpu, s);
update_cr8_intercept(vcpu);

--
2.9.0