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Commit b9877ce2 authored by Alexander Graf's avatar Alexander Graf Committed by Avi Kivity
Browse files

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: default avatarAlexander Graf <agraf@suse.de>
parent 928d78be

arch/powerpc/kvm/book3s_32_mmu_host.c

+8 −2
Original line number Diff line number Diff line
@@ -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));

}

arch/powerpc/kvm/book3s_64_mmu_host.c

+9 −2
Original line number Diff line number Diff line
@@ -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;