Track all possibilities for the optimized APIC map's logical modes
instead of overloading the pseudo-bitmap and treating any "unknown" value
as "invalid".
As documented by the now-stale comment above the mode values, the values
did have meaning when the optimized map was originally added. That
dependent logical was removed by commit e45115b62f9a ("KVM: x86: use
physical LAPIC array for logical x2APIC"), but the obfuscated behavior
and its comment were left behind.
Opportunistically rename "mode" to "logical_mode", partly to make it
clear that the "disabled" case applies only to the logical map, but also
to prove that there is no lurking code that expects "mode" to be a bitmap.
Functionally, this is a glorified nop.
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/include/asm/kvm_host.h | 21 ++++++++++--------
arch/x86/kvm/lapic.c | 38 ++++++++++++++++++++++++---------
2 files changed, 40 insertions(+), 19 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 1f51411f3112..0184e64ab555 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -955,19 +955,22 @@ struct kvm_arch_memory_slot {
};
/*
- * We use as the mode the number of bits allocated in the LDR for the
- * logical processor ID. It happens that these are all powers of two.
- * This makes it is very easy to detect cases where the APICs are
- * configured for multiple modes; in that case, we cannot use the map and
- * hence cannot use kvm_irq_delivery_to_apic_fast either.
+ * Track the mode of the optimized logical map, as the rules for decoding the
+ * destination vary per mode. Enabling the optimized logical map requires all
+ * software-enabled local APIs to be in the same mode, each addressable APIC to
+ * be mapped to only one MDA, and each MDA to map to at most one APIC.
*/
-#define KVM_APIC_MODE_XAPIC_CLUSTER 4
-#define KVM_APIC_MODE_XAPIC_FLAT 8
-#define KVM_APIC_MODE_X2APIC 16
+enum kvm_apic_logical_mode {
+ KVM_APIC_MODE_SW_DISABLED,
+ KVM_APIC_MODE_XAPIC_CLUSTER,
+ KVM_APIC_MODE_XAPIC_FLAT,
+ KVM_APIC_MODE_X2APIC,
+ KVM_APIC_MODE_MAP_DISABLED,
+};
struct kvm_apic_map {
struct rcu_head rcu;
- u8 mode;
+ enum kvm_apic_logical_mode logical_mode;
u32 max_apic_id;
union {
struct kvm_lapic *xapic_flat_map[8];
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 8209caffe3ab..3b6ef36b3963 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -168,7 +168,12 @@ static bool kvm_use_posted_timer_interrupt(struct kvm_vcpu *vcpu)
static inline bool kvm_apic_map_get_logical_dest(struct kvm_apic_map *map,
u32 dest_id, struct kvm_lapic ***cluster, u16 *mask) {
- switch (map->mode) {
+ switch (map->logical_mode) {
+ case KVM_APIC_MODE_SW_DISABLED:
+ /* Arbitrarily use the flat map so that @cluster isn't NULL. */
+ *cluster = map->xapic_flat_map;
+ *mask = 0;
+ return true;
case KVM_APIC_MODE_X2APIC: {
u32 offset = (dest_id >> 16) * 16;
u32 max_apic_id = map->max_apic_id;
@@ -193,8 +198,10 @@ static inline bool kvm_apic_map_get_logical_dest(struct kvm_apic_map *map,
*cluster = map->xapic_cluster_map[(dest_id >> 4) & 0xf];
*mask = dest_id & 0xf;
return true;
+ case KVM_APIC_MODE_MAP_DISABLED:
+ return false;
default:
- /* Not optimized. */
+ WARN_ON_ONCE(1);
return false;
}
}
@@ -256,10 +263,12 @@ void kvm_recalculate_apic_map(struct kvm *kvm)
goto out;
new->max_apic_id = max_id;
+ new->logical_mode = KVM_APIC_MODE_SW_DISABLED;
kvm_for_each_vcpu(i, vcpu, kvm) {
struct kvm_lapic *apic = vcpu->arch.apic;
struct kvm_lapic **cluster;
+ enum kvm_apic_logical_mode logical_mode;
u32 x2apic_id, physical_id;
u16 mask;
u32 ldr;
@@ -314,7 +323,8 @@ void kvm_recalculate_apic_map(struct kvm *kvm)
new->phys_map[physical_id] = apic;
}
- if (!kvm_apic_sw_enabled(apic))
+ if (new->logical_mode == KVM_APIC_MODE_MAP_DISABLED ||
+ !kvm_apic_sw_enabled(apic))
continue;
ldr = kvm_lapic_get_reg(apic, APIC_LDR);
@@ -322,25 +332,33 @@ void kvm_recalculate_apic_map(struct kvm *kvm)
continue;
if (apic_x2apic_mode(apic)) {
- new->mode |= KVM_APIC_MODE_X2APIC;
+ logical_mode = KVM_APIC_MODE_X2APIC;
} else {
ldr = GET_APIC_LOGICAL_ID(ldr);
if (kvm_lapic_get_reg(apic, APIC_DFR) == APIC_DFR_FLAT)
- new->mode |= KVM_APIC_MODE_XAPIC_FLAT;
+ logical_mode = KVM_APIC_MODE_XAPIC_FLAT;
else
- new->mode |= KVM_APIC_MODE_XAPIC_CLUSTER;
+ logical_mode = KVM_APIC_MODE_XAPIC_CLUSTER;
}
+ if (new->logical_mode != KVM_APIC_MODE_SW_DISABLED &&
+ new->logical_mode != logical_mode) {
+ new->logical_mode = KVM_APIC_MODE_MAP_DISABLED;
+ continue;
+ }
+ new->logical_mode = logical_mode;
- if (!kvm_apic_map_get_logical_dest(new, ldr, &cluster, &mask))
+ if (WARN_ON_ONCE(!kvm_apic_map_get_logical_dest(new, ldr,
+ &cluster, &mask))) {
+ new->logical_mode = KVM_APIC_MODE_MAP_DISABLED;
continue;
+ }
if (!mask)
continue;
ldr = ffs(mask) - 1;
if (!is_power_of_2(mask) || cluster[ldr]) {
- new->mode = KVM_APIC_MODE_XAPIC_FLAT |
- KVM_APIC_MODE_XAPIC_CLUSTER;
+ new->logical_mode = KVM_APIC_MODE_MAP_DISABLED;
continue;
}
cluster[ldr] = apic;
@@ -993,7 +1011,7 @@ static bool kvm_apic_is_broadcast_dest(struct kvm *kvm, struct kvm_lapic **src,
{
if (kvm->arch.x2apic_broadcast_quirk_disabled) {
if ((irq->dest_id == APIC_BROADCAST &&
- map->mode != KVM_APIC_MODE_X2APIC))
+ map->logical_mode != KVM_APIC_MODE_X2APIC))
return true;
if (irq->dest_id == X2APIC_BROADCAST)
return true;
--
2.37.2.672.g94769d06f0-goog
