Re: [PATCH 4/7] KVM: PPC: Add book3s_32 tlbie flush acceleration

Avi Kivity
2010-08-01T14:08:49Z

On 07/29/2010 04:04 PM, Alexander Graf wrote:
> On Book3s_32 the tlbie instruction flushed effective addresses by the mask
> 0x0ffff000. This is pretty hard to reflect with a hash that hashes ~0xfff, so
> to speed up that target we should also keep a special hash around for it.
>
>
> static inline u64 kvmppc_mmu_hash_vpte(u64 vpage)
> {
> return hash_64(vpage& 0xfffffffffULL, HPTEG_HASH_BITS_VPTE);
> @@ -66,6 +72,11 @@ void kvmppc_mmu_hpte_cache_map(struct kvm_vcpu *vcpu, struct hpte_cache *pte)
> index = kvmppc_mmu_hash_pte(pte->pte.eaddr);
> hlist_add_head_rcu(&pte->list_pte,&vcpu->arch.hpte_hash_pte[index]);
>
> + /* Add to ePTE_long list */
> + index = kvmppc_mmu_hash_pte_long(pte->pte.eaddr);
> + hlist_add_head_rcu(&pte->list_pte_long,
> + &vcpu->arch.hpte_hash_pte_long[index]);
> +

Isn't it better to make operations on this list conditional on
Book3s_32? Hashes are expensive since they usually cost cache misses.

Can of course be done later as an optimization.

--
error compiling committee.c: too many arguments to function