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| author | Alexander Graf <agraf@suse.de> | 2010-08-02 23:48:53 +0400 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2010-10-24 12:52:08 +0400 |
| commit | b9877ce2994cc812f00dbb2adb88c1749b6dac86 (patch) | |
| tree | e922a4f2db2f8e226f1e9cf9ec1234fe7b56a41e | |
| parent | 928d78be54014e65498e289fdc3f82acc4b804a9 (diff) | |
| download | linux-b9877ce2994cc812f00dbb2adb88c1749b6dac86.tar.xz | |
KVM: PPC: Revert "KVM: PPC: Use kernel hash function"
It turns out the in-kernel hash function is sub-optimal for our subtle
hash inputs where every bit is significant. So let's revert to the original
hash functions.
This reverts commit 05340ab4f9a6626f7a2e8f9fe5397c61d494f445.
Signed-off-by: Alexander Graf <agraf@suse.de>
| -rw-r--r-- | arch/powerpc/kvm/book3s_32_mmu_host.c | 10 | ||||
| -rw-r--r-- | arch/powerpc/kvm/book3s_64_mmu_host.c | 11 |
2 files changed, 17 insertions, 4 deletions
diff --git a/arch/powerpc/kvm/book3s_32_mmu_host.c b/arch/powerpc/kvm/book3s_32_mmu_host.c index 343452cff9b2..57dddeb23b9b 100644 --- a/arch/powerpc/kvm/book3s_32_mmu_host.c +++ b/arch/powerpc/kvm/book3s_32_mmu_host.c @@ -19,7 +19,6 @@ */ #include <linux/kvm_host.h> -#include <linux/hash.h> #include <asm/kvm_ppc.h> #include <asm/kvm_book3s.h> @@ -77,7 +76,14 @@ void kvmppc_mmu_invalidate_pte(struct kvm_vcpu *vcpu, struct hpte_cache *pte) * a hash, so we don't waste cycles on looping */ static u16 kvmppc_sid_hash(struct kvm_vcpu *vcpu, u64 gvsid) { - return hash_64(gvsid, SID_MAP_BITS); + return (u16)(((gvsid >> (SID_MAP_BITS * 7)) & SID_MAP_MASK) ^ + ((gvsid >> (SID_MAP_BITS * 6)) & SID_MAP_MASK) ^ + ((gvsid >> (SID_MAP_BITS * 5)) & SID_MAP_MASK) ^ + ((gvsid >> (SID_MAP_BITS * 4)) & SID_MAP_MASK) ^ + ((gvsid >> (SID_MAP_BITS * 3)) & SID_MAP_MASK) ^ + ((gvsid >> (SID_MAP_BITS * 2)) & SID_MAP_MASK) ^ + ((gvsid >> (SID_MAP_BITS * 1)) & SID_MAP_MASK) ^ + ((gvsid >> (SID_MAP_BITS * 0)) & SID_MAP_MASK)); } diff --git a/arch/powerpc/kvm/book3s_64_mmu_host.c b/arch/powerpc/kvm/book3s_64_mmu_host.c index 321c931f691c..e7c4d00b99cf 100644 --- a/arch/powerpc/kvm/book3s_64_mmu_host.c +++ b/arch/powerpc/kvm/book3s_64_mmu_host.c @@ -20,7 +20,6 @@ */ #include <linux/kvm_host.h> -#include <linux/hash.h> #include <asm/kvm_ppc.h> #include <asm/kvm_book3s.h> @@ -44,9 +43,17 @@ void kvmppc_mmu_invalidate_pte(struct kvm_vcpu *vcpu, struct hpte_cache *pte) * a hash, so we don't waste cycles on looping */ static u16 kvmppc_sid_hash(struct kvm_vcpu *vcpu, u64 gvsid) { - return hash_64(gvsid, SID_MAP_BITS); + return (u16)(((gvsid >> (SID_MAP_BITS * 7)) & SID_MAP_MASK) ^ + ((gvsid >> (SID_MAP_BITS * 6)) & SID_MAP_MASK) ^ + ((gvsid >> (SID_MAP_BITS * 5)) & SID_MAP_MASK) ^ + ((gvsid >> (SID_MAP_BITS * 4)) & SID_MAP_MASK) ^ + ((gvsid >> (SID_MAP_BITS * 3)) & SID_MAP_MASK) ^ + ((gvsid >> (SID_MAP_BITS * 2)) & SID_MAP_MASK) ^ + ((gvsid >> (SID_MAP_BITS * 1)) & SID_MAP_MASK) ^ + ((gvsid >> (SID_MAP_BITS * 0)) & SID_MAP_MASK)); } + static struct kvmppc_sid_map *find_sid_vsid(struct kvm_vcpu *vcpu, u64 gvsid) { struct kvmppc_sid_map *map; |