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Subject[PATCH v2 03/16] KVM: MMU: properly assert spte on rmap walking path
Only test present bit is not enough since mmio spte is also set this
bit, use is_shadow_present_pte() instead of it

Also move the BUG_ONs to the common function to cleanup the code

Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
---
arch/x86/kvm/mmu.c | 38 ++++++++++++++++++++------------------
1 files changed, 20 insertions(+), 18 deletions(-)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index aee13c6..91518b6 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -993,17 +993,25 @@ struct rmap_iterator {
*/
static u64 *rmap_get_first(unsigned long rmap, struct rmap_iterator *iter)
{
+ u64 *sptep;
+
if (!rmap)
return NULL;

if (!(rmap & 1)) {
iter->desc = NULL;
- return (u64 *)rmap;
+ sptep = (u64 *)rmap;
+
+ goto exit;
}

iter->desc = (struct pte_list_desc *)(rmap & ~1ul);
iter->pos = 0;
- return iter->desc->sptes[iter->pos];
+ sptep = iter->desc->sptes[iter->pos];
+
+exit:
+ WARN_ON(sptep && !is_shadow_present_pte(*sptep));
+ return sptep;
}

/*
@@ -1013,14 +1021,14 @@ static u64 *rmap_get_first(unsigned long rmap, struct rmap_iterator *iter)
*/
static u64 *rmap_get_next(struct rmap_iterator *iter)
{
+ u64 *sptep = NULL;
+
if (iter->desc) {
if (iter->pos < PTE_LIST_EXT - 1) {
- u64 *sptep;
-
++iter->pos;
sptep = iter->desc->sptes[iter->pos];
if (sptep)
- return sptep;
+ goto exit;
}

iter->desc = iter->desc->more;
@@ -1028,11 +1036,14 @@ static u64 *rmap_get_next(struct rmap_iterator *iter)
if (iter->desc) {
iter->pos = 0;
/* desc->sptes[0] cannot be NULL */
- return iter->desc->sptes[iter->pos];
+ sptep = iter->desc->sptes[iter->pos];
+ goto exit;
}
}

- return NULL;
+exit:
+ WARN_ON(sptep && !is_shadow_present_pte(*sptep));
+ return sptep;
}

static void drop_spte(struct kvm *kvm, u64 *sptep)
@@ -1048,7 +1059,6 @@ static int __rmap_write_protect(struct kvm *kvm, unsigned long *rmapp, int level
int write_protected = 0;

for (sptep = rmap_get_first(*rmapp, &iter); sptep;) {
- BUG_ON(!(*sptep & PT_PRESENT_MASK));
rmap_printk("rmap_write_protect: spte %p %llx\n", sptep, *sptep);

if (!is_writable_pte(*sptep)) {
@@ -1123,7 +1133,6 @@ static int kvm_unmap_rmapp(struct kvm *kvm, unsigned long *rmapp,
int need_tlb_flush = 0;

while ((sptep = rmap_get_first(*rmapp, &iter))) {
- BUG_ON(!(*sptep & PT_PRESENT_MASK));
rmap_printk("kvm_rmap_unmap_hva: spte %p %llx\n", sptep, *sptep);

drop_spte(kvm, sptep);
@@ -1147,7 +1156,6 @@ static int kvm_set_pte_rmapp(struct kvm *kvm, unsigned long *rmapp,
new_pfn = pte_pfn(*ptep);

for (sptep = rmap_get_first(*rmapp, &iter); sptep;) {
- BUG_ON(!is_shadow_present_pte(*sptep));
rmap_printk("kvm_set_pte_rmapp: spte %p %llx\n", sptep, *sptep);

need_flush = 1;
@@ -1242,14 +1250,11 @@ static int kvm_age_rmapp(struct kvm *kvm, unsigned long *rmapp,
return kvm_unmap_rmapp(kvm, rmapp, data);

for (sptep = rmap_get_first(*rmapp, &iter); sptep;
- sptep = rmap_get_next(&iter)) {
- BUG_ON(!(*sptep & PT_PRESENT_MASK));
-
+ sptep = rmap_get_next(&iter))
if (*sptep & PT_ACCESSED_MASK) {
young = 1;
clear_bit(PT_ACCESSED_SHIFT, (unsigned long *)sptep);
}
- }

return young;
}
@@ -1270,14 +1275,11 @@ static int kvm_test_age_rmapp(struct kvm *kvm, unsigned long *rmapp,
goto out;

for (sptep = rmap_get_first(*rmapp, &iter); sptep;
- sptep = rmap_get_next(&iter)) {
- BUG_ON(!(*sptep & PT_PRESENT_MASK));
-
+ sptep = rmap_get_next(&iter))
if (*sptep & PT_ACCESSED_MASK) {
young = 1;
break;
}
- }
out:
return young;
}
--
1.7.7.6


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