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Subject[PATCH 7/8] KVM: x86: avoid logical_map when it is invalid
Date
We want to support mixed modes and the easiest solution is to avoid
optimizing those weird and unlikely scenarios.

Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
---
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/lapic.c | 16 ++++++++++++++++
arch/x86/kvm/lapic.h | 4 ++++
3 files changed, 21 insertions(+)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 26d0f0f646d3..fec3188cabbb 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -554,6 +554,7 @@ struct kvm_arch_memory_slot {

struct kvm_apic_map {
struct rcu_head rcu;
+ u8 mode;
u8 ldr_bits;
/* fields bellow are used to decode ldr values in different modes */
u32 cid_shift, cid_mask, lid_mask;
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index fab007509047..621d9df6ac63 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -162,16 +162,19 @@ static void recalculate_apic_map(struct kvm *kvm)
new->ldr_bits = 32;
new->cid_shift = 16;
new->cid_mask = new->lid_mask = 0xffff;
+ new->mode |= KVM_APIC_MODE_X2APIC;
} else if (kvm_apic_get_reg(apic, APIC_LDR)) {
if (kvm_apic_get_reg(apic, APIC_DFR) ==
APIC_DFR_CLUSTER) {
new->cid_shift = 4;
new->cid_mask = 0xf;
new->lid_mask = 0xf;
+ new->mode |= KVM_APIC_MODE_XAPIC_CLUSTER;
} else {
new->cid_shift = 8;
new->cid_mask = 0;
new->lid_mask = 0xff;
+ new->mode |= KVM_APIC_MODE_XAPIC_FLAT;
}
}

@@ -201,6 +204,13 @@ static void recalculate_apic_map(struct kvm *kvm)

if (aid < ARRAY_SIZE(new->phys_map))
new->phys_map[aid] = apic;
+
+ /* The logical map is definitely wrong if we have multiple
+ * modes at the same time. Physical is still right though.
+ */
+ if (hweight8(new->mode) != 1)
+ continue;
+
if (lid && cid < ARRAY_SIZE(new->logical_map))
new->logical_map[cid][ffs(lid) - 1] = apic;
}
@@ -720,6 +730,12 @@ bool kvm_irq_delivery_to_apic_fast(struct kvm *kvm, struct kvm_lapic *src,
if (cid >= ARRAY_SIZE(map->logical_map))
goto out;

+ if (hweight8(map->mode) != 1) {
+ /* Not deliverable with optimized map. */
+ ret = false;
+ goto out;
+ }
+
dst = map->logical_map[cid];

bitmap = apic_logical_id(map, mda);
diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index c1ef25c89508..fd0197a93862 100644
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -8,6 +8,10 @@
#define KVM_APIC_INIT 0
#define KVM_APIC_SIPI 1

+#define KVM_APIC_MODE_XAPIC_FLAT (1 << 0)
+#define KVM_APIC_MODE_XAPIC_CLUSTER (1 << 1)
+#define KVM_APIC_MODE_X2APIC (1 << 2)
+
struct kvm_timer {
struct hrtimer timer;
s64 period; /* unit: ns */
--
2.2.2


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