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linux/arch/powerpc/kvm/book3s_mmu_hpte.c
Alexander Graf e7c1d14e3b KVM: PPC: Make invalidation code more reliable 
There is a race condition in the pte invalidation code path where we can't
be sure if a pte was invalidated already. So let's move the spin lock around
to get rid of the race.

Signed-off-by: Alexander Graf <agraf@suse.de>
2010-10-24 10:52:06 +02:00

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/*
* Copyright (C) 2010 SUSE Linux Products GmbH. All rights reserved.
*
* Authors:
* Alexander Graf <agraf@suse.de>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License, version 2, as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include <linux/kvm_host.h>
#include <linux/hash.h>
#include <linux/slab.h>
#include "trace.h"
#include <asm/kvm_ppc.h>
#include <asm/kvm_book3s.h>
#include <asm/machdep.h>
#include <asm/mmu_context.h>
#include <asm/hw_irq.h>
#define PTE_SIZE 12
static struct kmem_cache *hpte_cache;
static inline u64 kvmppc_mmu_hash_pte(u64 eaddr)
{
return hash_64(eaddr >> PTE_SIZE, HPTEG_HASH_BITS_PTE);
}
static inline u64 kvmppc_mmu_hash_pte_long(u64 eaddr)
{
return hash_64((eaddr & 0x0ffff000) >> PTE_SIZE,
HPTEG_HASH_BITS_PTE_LONG);
}
static inline u64 kvmppc_mmu_hash_vpte(u64 vpage)
{
return hash_64(vpage & 0xfffffffffULL, HPTEG_HASH_BITS_VPTE);
}
static inline u64 kvmppc_mmu_hash_vpte_long(u64 vpage)
{
return hash_64((vpage & 0xffffff000ULL) >> 12,
HPTEG_HASH_BITS_VPTE_LONG);
}
void kvmppc_mmu_hpte_cache_map(struct kvm_vcpu *vcpu, struct hpte_cache *pte)
{
u64 index;
trace_kvm_book3s_mmu_map(pte);
spin_lock(&vcpu->arch.mmu_lock);
/* Add to ePTE list */
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]);
/* Add to vPTE list */
index = kvmppc_mmu_hash_vpte(pte->pte.vpage);
hlist_add_head_rcu(&pte->list_vpte, &vcpu->arch.hpte_hash_vpte[index]);
/* Add to vPTE_long list */
index = kvmppc_mmu_hash_vpte_long(pte->pte.vpage);
hlist_add_head_rcu(&pte->list_vpte_long,
&vcpu->arch.hpte_hash_vpte_long[index]);
spin_unlock(&vcpu->arch.mmu_lock);
}
static void free_pte_rcu(struct rcu_head *head)
{
struct hpte_cache *pte = container_of(head, struct hpte_cache, rcu_head);
kmem_cache_free(hpte_cache, pte);
}
static void invalidate_pte(struct kvm_vcpu *vcpu, struct hpte_cache *pte)
{
trace_kvm_book3s_mmu_invalidate(pte);
/* Different for 32 and 64 bit */
kvmppc_mmu_invalidate_pte(vcpu, pte);
spin_lock(&vcpu->arch.mmu_lock);
/* pte already invalidated in between? */
if (hlist_unhashed(&pte->list_pte)) {
spin_unlock(&vcpu->arch.mmu_lock);
return;
}
hlist_del_init_rcu(&pte->list_pte);
hlist_del_init_rcu(&pte->list_pte_long);
hlist_del_init_rcu(&pte->list_vpte);
hlist_del_init_rcu(&pte->list_vpte_long);
if (pte->pte.may_write)
kvm_release_pfn_dirty(pte->pfn);
else
kvm_release_pfn_clean(pte->pfn);
spin_unlock(&vcpu->arch.mmu_lock);
vcpu->arch.hpte_cache_count--;
call_rcu(&pte->rcu_head, free_pte_rcu);
}
static void kvmppc_mmu_pte_flush_all(struct kvm_vcpu *vcpu)
{
struct hpte_cache *pte;
struct hlist_node *node;
int i;
rcu_read_lock();
for (i = 0; i < HPTEG_HASH_NUM_VPTE_LONG; i++) {
struct hlist_head *list = &vcpu->arch.hpte_hash_vpte_long[i];
hlist_for_each_entry_rcu(pte, node, list, list_vpte_long)
invalidate_pte(vcpu, pte);
}
rcu_read_unlock();
}
static void kvmppc_mmu_pte_flush_page(struct kvm_vcpu *vcpu, ulong guest_ea)
{
struct hlist_head *list;
struct hlist_node *node;
struct hpte_cache *pte;
/* Find the list of entries in the map */
list = &vcpu->arch.hpte_hash_pte[kvmppc_mmu_hash_pte(guest_ea)];
rcu_read_lock();
/* Check the list for matching entries and invalidate */
hlist_for_each_entry_rcu(pte, node, list, list_pte)
if ((pte->pte.eaddr & ~0xfffUL) == guest_ea)
invalidate_pte(vcpu, pte);
rcu_read_unlock();
}
static void kvmppc_mmu_pte_flush_long(struct kvm_vcpu *vcpu, ulong guest_ea)
{
struct hlist_head *list;
struct hlist_node *node;
struct hpte_cache *pte;
/* Find the list of entries in the map */
list = &vcpu->arch.hpte_hash_pte_long[
kvmppc_mmu_hash_pte_long(guest_ea)];
rcu_read_lock();
/* Check the list for matching entries and invalidate */
hlist_for_each_entry_rcu(pte, node, list, list_pte_long)
if ((pte->pte.eaddr & 0x0ffff000UL) == guest_ea)
invalidate_pte(vcpu, pte);
rcu_read_unlock();
}
void kvmppc_mmu_pte_flush(struct kvm_vcpu *vcpu, ulong guest_ea, ulong ea_mask)
{
trace_kvm_book3s_mmu_flush("", vcpu, guest_ea, ea_mask);
guest_ea &= ea_mask;
switch (ea_mask) {
case ~0xfffUL:
kvmppc_mmu_pte_flush_page(vcpu, guest_ea);
break;
case 0x0ffff000:
kvmppc_mmu_pte_flush_long(vcpu, guest_ea);
break;
case 0:
/* Doing a complete flush -> start from scratch */
kvmppc_mmu_pte_flush_all(vcpu);
break;
default:
WARN_ON(1);
break;
}
}
/* Flush with mask 0xfffffffff */
static void kvmppc_mmu_pte_vflush_short(struct kvm_vcpu *vcpu, u64 guest_vp)
{
struct hlist_head *list;
struct hlist_node *node;
struct hpte_cache *pte;
u64 vp_mask = 0xfffffffffULL;
list = &vcpu->arch.hpte_hash_vpte[kvmppc_mmu_hash_vpte(guest_vp)];
rcu_read_lock();
/* Check the list for matching entries and invalidate */
hlist_for_each_entry_rcu(pte, node, list, list_vpte)
if ((pte->pte.vpage & vp_mask) == guest_vp)
invalidate_pte(vcpu, pte);
rcu_read_unlock();
}
/* Flush with mask 0xffffff000 */
static void kvmppc_mmu_pte_vflush_long(struct kvm_vcpu *vcpu, u64 guest_vp)
{
struct hlist_head *list;
struct hlist_node *node;
struct hpte_cache *pte;
u64 vp_mask = 0xffffff000ULL;
list = &vcpu->arch.hpte_hash_vpte_long[
kvmppc_mmu_hash_vpte_long(guest_vp)];
rcu_read_lock();
/* Check the list for matching entries and invalidate */
hlist_for_each_entry_rcu(pte, node, list, list_vpte_long)
if ((pte->pte.vpage & vp_mask) == guest_vp)
invalidate_pte(vcpu, pte);
rcu_read_unlock();
}
void kvmppc_mmu_pte_vflush(struct kvm_vcpu *vcpu, u64 guest_vp, u64 vp_mask)
{
trace_kvm_book3s_mmu_flush("v", vcpu, guest_vp, vp_mask);
guest_vp &= vp_mask;
switch(vp_mask) {
case 0xfffffffffULL:
kvmppc_mmu_pte_vflush_short(vcpu, guest_vp);
break;
case 0xffffff000ULL:
kvmppc_mmu_pte_vflush_long(vcpu, guest_vp);
break;
default:
WARN_ON(1);
return;
}
}
void kvmppc_mmu_pte_pflush(struct kvm_vcpu *vcpu, ulong pa_start, ulong pa_end)
{
struct hlist_node *node;
struct hpte_cache *pte;
int i;
trace_kvm_book3s_mmu_flush("p", vcpu, pa_start, pa_end);
rcu_read_lock();
for (i = 0; i < HPTEG_HASH_NUM_VPTE_LONG; i++) {
struct hlist_head *list = &vcpu->arch.hpte_hash_vpte_long[i];
hlist_for_each_entry_rcu(pte, node, list, list_vpte_long)
if ((pte->pte.raddr >= pa_start) &&
(pte->pte.raddr < pa_end))
invalidate_pte(vcpu, pte);
}
rcu_read_unlock();
}
struct hpte_cache *kvmppc_mmu_hpte_cache_next(struct kvm_vcpu *vcpu)
{
struct hpte_cache *pte;
pte = kmem_cache_zalloc(hpte_cache, GFP_KERNEL);
vcpu->arch.hpte_cache_count++;
if (vcpu->arch.hpte_cache_count == HPTEG_CACHE_NUM)
kvmppc_mmu_pte_flush_all(vcpu);
return pte;
}
void kvmppc_mmu_hpte_destroy(struct kvm_vcpu *vcpu)
{
kvmppc_mmu_pte_flush(vcpu, 0, 0);
}
static void kvmppc_mmu_hpte_init_hash(struct hlist_head *hash_list, int len)
{
int i;
for (i = 0; i < len; i++)
INIT_HLIST_HEAD(&hash_list[i]);
}
int kvmppc_mmu_hpte_init(struct kvm_vcpu *vcpu)
{
/* init hpte lookup hashes */
kvmppc_mmu_hpte_init_hash(vcpu->arch.hpte_hash_pte,
ARRAY_SIZE(vcpu->arch.hpte_hash_pte));
kvmppc_mmu_hpte_init_hash(vcpu->arch.hpte_hash_pte_long,
ARRAY_SIZE(vcpu->arch.hpte_hash_pte_long));
kvmppc_mmu_hpte_init_hash(vcpu->arch.hpte_hash_vpte,
ARRAY_SIZE(vcpu->arch.hpte_hash_vpte));
kvmppc_mmu_hpte_init_hash(vcpu->arch.hpte_hash_vpte_long,
ARRAY_SIZE(vcpu->arch.hpte_hash_vpte_long));
spin_lock_init(&vcpu->arch.mmu_lock);
return 0;
}
int kvmppc_mmu_hpte_sysinit(void)
{
/* init hpte slab cache */
hpte_cache = kmem_cache_create("kvm-spt", sizeof(struct hpte_cache),
sizeof(struct hpte_cache), 0, NULL);
return 0;
}
void kvmppc_mmu_hpte_sysexit(void)
{
kmem_cache_destroy(hpte_cache);
}
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