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Subject[PATCH 8/8] KVM: x86: simplify kvm_apic_map
Date
recalculate_apic_map() uses two passes over all VCPUs.  This is a relic
from time when we selected a global mode in the first pass and set up
the optimized table in the second pass (to have a consistent mode).

Recent changes made mixed mode unoptimized and we can do it in one pass.
Format of logical MDA is a function of the mode, so we encode it in
apic_logical_id() and drop obsoleted variables from the struct.

Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
---
arch/x86/include/asm/kvm_host.h | 3 --
arch/x86/kvm/lapic.c | 78 ++++++++++-------------------------------
arch/x86/kvm/lapic.h | 29 ++++++++-------
3 files changed, 36 insertions(+), 74 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index fec3188cabbb..14b6b0fd17b1 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -555,9 +555,6 @@ 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;
struct kvm_lapic *phys_map[256];
/* first index is cluster id second is cpu id in a cluster */
struct kvm_lapic *logical_map[16][16];
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 621d9df6ac63..f74557791a77 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -146,49 +146,6 @@ static void recalculate_apic_map(struct kvm *kvm)
if (!new)
goto out;

- new->ldr_bits = 8;
- /* flat mode is default */
- new->cid_shift = 8;
- new->cid_mask = 0;
- new->lid_mask = 0xff;
-
- kvm_for_each_vcpu(i, vcpu, kvm) {
- struct kvm_lapic *apic = vcpu->arch.apic;
-
- if (!kvm_apic_present(vcpu))
- continue;
-
- if (apic_x2apic_mode(apic)) {
- 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;
- }
- }
-
- /*
- * All APICs have to be configured in the same mode by an OS.
- * We take advatage of this while building logical id loockup
- * table. After reset APICs are in software disabled mode, so if
- * we find apic with different setting we assume this is the mode
- * OS wants all apics to be in; build lookup table accordingly.
- */
- if (kvm_apic_sw_enabled(apic))
- break;
- }
-
kvm_for_each_vcpu(i, vcpu, kvm) {
struct kvm_lapic *apic = vcpu->arch.apic;
u16 cid, lid;
@@ -198,17 +155,22 @@ static void recalculate_apic_map(struct kvm *kvm)
continue;

aid = kvm_apic_id(apic);
- ldr = kvm_apic_get_reg(apic, APIC_LDR);
- cid = apic_cluster_id(new, ldr);
- lid = apic_logical_id(new, ldr);
-
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)
+ ldr = kvm_apic_get_reg(apic, APIC_LDR);
+
+ if (apic_x2apic_mode(apic)) {
+ new->mode |= KVM_APIC_MODE_X2APIC;
+ } else if (ldr) {
+ ldr = GET_APIC_LOGICAL_ID(ldr);
+ if (kvm_apic_get_reg(apic, APIC_DFR) == APIC_DFR_FLAT)
+ new->mode |= KVM_APIC_MODE_XAPIC_FLAT;
+ else
+ new->mode |= KVM_APIC_MODE_XAPIC_CLUSTER;
+ }
+
+ if (!apic_logical_id(new, ldr, &cid, &lid))
continue;

if (lid && cid < ARRAY_SIZE(new->logical_map))
@@ -724,22 +686,20 @@ bool kvm_irq_delivery_to_apic_fast(struct kvm *kvm, struct kvm_lapic *src,

dst = &map->phys_map[irq->dest_id];
} else {
- u32 mda = irq->dest_id << (32 - map->ldr_bits);
- u16 cid = apic_cluster_id(map, mda);
+ u16 cid;

- if (cid >= ARRAY_SIZE(map->logical_map))
- goto out;
-
- if (hweight8(map->mode) != 1) {
+ if (!apic_logical_id(map, irq->dest_id, &cid, (u16 *)&bitmap))
+ {
/* Not deliverable with optimized map. */
ret = false;
goto out;
}

+ if (cid >= ARRAY_SIZE(map->logical_map))
+ goto out;
+
dst = map->logical_map[cid];

- bitmap = apic_logical_id(map, mda);
-
if (irq->delivery_mode == APIC_DM_LOWEST) {
int l = -1;
for_each_set_bit(i, &bitmap, 16) {
diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index fd0197a93862..320716e301a8 100644
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -151,19 +151,24 @@ static inline bool kvm_apic_vid_enabled(struct kvm *kvm)
return kvm_x86_ops->vm_has_apicv(kvm);
}

-static inline u16 apic_cluster_id(struct kvm_apic_map *map, u32 ldr)
+static inline bool
+apic_logical_id(struct kvm_apic_map *map, u32 ldr, u16 *cid, u16 *lid)
{
- u16 cid;
- ldr >>= 32 - map->ldr_bits;
- cid = (ldr >> map->cid_shift) & map->cid_mask;
-
- return cid;
-}
-
-static inline u16 apic_logical_id(struct kvm_apic_map *map, u32 ldr)
-{
- ldr >>= (32 - map->ldr_bits);
- return ldr & map->lid_mask;
+ switch (map->mode) {
+ case KVM_APIC_MODE_XAPIC_FLAT:
+ *cid = 0;
+ *lid = ldr & 0xff;
+ return true;
+ case KVM_APIC_MODE_XAPIC_CLUSTER:
+ *cid = (ldr >> 4) & 0xf;
+ *lid = ldr & 0xf;
+ return true;
+ case KVM_APIC_MODE_X2APIC:
+ *cid = ldr >> 16;
+ *lid = ldr & 0xffff;
+ return true;
+ }
+ return false;
}

static inline bool kvm_apic_has_events(struct kvm_vcpu *vcpu)
--
2.2.2


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