[RESEND PATCH 2/3] arch/powerpc/kvm: Optimize the server number -> ICP lookup

[Gautam Menghani]

Given a server number, kvmppc_xics_find_server() does a linear search
over the vcpus of a VM. Optimize this logic by using an array to
maintain the mapping between server number -> icp.

Signed-off-by: Gautam Menghani <gau...@linux.ibm.com>
---
 arch/powerpc/kvm/book3s_xics.c |  4 ++--
 arch/powerpc/kvm/book3s_xics.h | 10 ++--------
 2 files changed, 4 insertions(+), 10 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_xics.c b/arch/powerpc/kvm/book3s_xics.c
index 12de526f04c4..1dc2f77571e7 100644
--- a/arch/powerpc/kvm/book3s_xics.c
+++ b/arch/powerpc/kvm/book3s_xics.c
@@ -47,8 +47,6 @@
  * TODO
  * ====
  *
- * - Speed up server# -> ICP lookup (array ? hash table ?)
- *
  * - Make ICS lockless as well, or at least a per-interrupt lock or hashed
  *   locks array to improve scalability
  */
@@ -1062,6 +1060,7 @@ static struct kvmppc_ics *kvmppc_xics_create_ics(struct 
kvm *kvm,
 static int kvmppc_xics_create_icp(struct kvm_vcpu *vcpu, unsigned long 
server_num)
 {
        struct kvmppc_icp *icp;
+       struct kvm *kvm = vcpu->kvm;
 
        if (!vcpu->kvm->arch.xics)
                return -ENODEV;
@@ -1078,6 +1077,7 @@ static int kvmppc_xics_create_icp(struct kvm_vcpu *vcpu, 
unsigned long server_nu
        icp->state.mfrr = MASKED;
        icp->state.pending_pri = MASKED;
        vcpu->arch.icp = icp;
+       kvm->arch.xics->icps[server_num] = icp;
 
        XICS_DBG("created server for vcpu %d\n", vcpu->vcpu_id);
 
diff --git a/arch/powerpc/kvm/book3s_xics.h b/arch/powerpc/kvm/book3s_xics.h
index 8fcb34ea47a4..feeb0897d555 100644
--- a/arch/powerpc/kvm/book3s_xics.h
+++ b/arch/powerpc/kvm/book3s_xics.h
@@ -111,19 +111,13 @@ struct kvmppc_xics {
        u32 err_noics;
        u32 err_noicp;
        struct kvmppc_ics *ics[KVMPPC_XICS_MAX_ICS_ID + 1];
+       DECLARE_FLEX_ARRAY(struct kvmppc_icp *, icps);
 };
 
 static inline struct kvmppc_icp *kvmppc_xics_find_server(struct kvm *kvm,
                                                         u32 nr)
 {
-       struct kvm_vcpu *vcpu = NULL;
-       unsigned long i;
-
-       kvm_for_each_vcpu(i, vcpu, kvm) {
-               if (vcpu->arch.icp && nr == vcpu->arch.icp->server_num)
-                       return vcpu->arch.icp;
-       }
-       return NULL;
+       return kvm->arch.xics->icps[nr];
 }
 
 static inline struct kvmppc_ics *kvmppc_xics_find_ics(struct kvmppc_xics *xics,
-- 
2.44.0