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Diffstat (limited to 'virt/kvm/arm/mmu.c')
-rw-r--r--virt/kvm/arm/mmu.c36
1 files changed, 24 insertions, 12 deletions
diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
index 313ee646480f..e2e5effba2a9 100644
--- a/virt/kvm/arm/mmu.c
+++ b/virt/kvm/arm/mmu.c
@@ -295,6 +295,13 @@ static void unmap_stage2_range(struct kvm *kvm, phys_addr_t start, u64 size)
assert_spin_locked(&kvm->mmu_lock);
pgd = kvm->arch.pgd + stage2_pgd_index(addr);
do {
+ /*
+ * Make sure the page table is still active, as another thread
+ * could have possibly freed the page table, while we released
+ * the lock.
+ */
+ if (!READ_ONCE(kvm->arch.pgd))
+ break;
next = stage2_pgd_addr_end(addr, end);
if (!stage2_pgd_none(*pgd))
unmap_stage2_puds(kvm, pgd, addr, next);
@@ -829,22 +836,22 @@ void stage2_unmap_vm(struct kvm *kvm)
* Walks the level-1 page table pointed to by kvm->arch.pgd and frees all
* underlying level-2 and level-3 tables before freeing the actual level-1 table
* and setting the struct pointer to NULL.
- *
- * Note we don't need locking here as this is only called when the VM is
- * destroyed, which can only be done once.
*/
void kvm_free_stage2_pgd(struct kvm *kvm)
{
- if (kvm->arch.pgd == NULL)
- return;
+ void *pgd = NULL;
spin_lock(&kvm->mmu_lock);
- unmap_stage2_range(kvm, 0, KVM_PHYS_SIZE);
+ if (kvm->arch.pgd) {
+ unmap_stage2_range(kvm, 0, KVM_PHYS_SIZE);
+ pgd = READ_ONCE(kvm->arch.pgd);
+ kvm->arch.pgd = NULL;
+ }
spin_unlock(&kvm->mmu_lock);
/* Free the HW pgd, one page at a time */
- free_pages_exact(kvm->arch.pgd, S2_PGD_SIZE);
- kvm->arch.pgd = NULL;
+ if (pgd)
+ free_pages_exact(pgd, S2_PGD_SIZE);
}
static pud_t *stage2_get_pud(struct kvm *kvm, struct kvm_mmu_memory_cache *cache,
@@ -872,6 +879,9 @@ static pmd_t *stage2_get_pmd(struct kvm *kvm, struct kvm_mmu_memory_cache *cache
pmd_t *pmd;
pud = stage2_get_pud(kvm, cache, addr);
+ if (!pud)
+ return NULL;
+
if (stage2_pud_none(*pud)) {
if (!cache)
return NULL;
@@ -1170,11 +1180,13 @@ static void stage2_wp_range(struct kvm *kvm, phys_addr_t addr, phys_addr_t end)
* large. Otherwise, we may see kernel panics with
* CONFIG_DETECT_HUNG_TASK, CONFIG_LOCKUP_DETECTOR,
* CONFIG_LOCKDEP. Additionally, holding the lock too long
- * will also starve other vCPUs.
+ * will also starve other vCPUs. We have to also make sure
+ * that the page tables are not freed while we released
+ * the lock.
*/
- if (need_resched() || spin_needbreak(&kvm->mmu_lock))
- cond_resched_lock(&kvm->mmu_lock);
-
+ cond_resched_lock(&kvm->mmu_lock);
+ if (!READ_ONCE(kvm->arch.pgd))
+ break;
next = stage2_pgd_addr_end(addr, end);
if (stage2_pgd_present(*pgd))
stage2_wp_puds(pgd, addr, next);