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 <rkrc...@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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