This adds locking to the memslots so they can be looked up with only
the mmu_lock. Entries with memslot->userspace_addr have to be ignored
because they're not fully inserted yet.
Signed-off-by: Andrea Arcangeli <[EMAIL PROTECTED]>
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 8a90403..35a2ee0 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3219,14 +3249,20 @@ int kvm_arch_set_memory_region(struct kvm *kvm,
*/
if (!user_alloc) {
if (npages && !old.rmap) {
- memslot->userspace_addr = do_mmap(NULL, 0,
- npages * PAGE_SIZE,
- PROT_READ | PROT_WRITE,
- MAP_SHARED | MAP_ANONYMOUS,
- 0);
-
- if (IS_ERR((void *)memslot->userspace_addr))
- return PTR_ERR((void *)memslot->userspace_addr);
+ unsigned long userspace_addr;
+
+ userspace_addr = do_mmap(NULL, 0,
+ npages * PAGE_SIZE,
+ PROT_READ | PROT_WRITE,
+ MAP_SHARED | MAP_ANONYMOUS,
+ 0);
+ if (IS_ERR((void *)userspace_addr))
+ return PTR_ERR((void *)userspace_addr);
+
+ /* set userspace_addr atomically for kvm_hva_to_rmapp */
+ spin_lock(&kvm->mmu_lock);
+ memslot->userspace_addr = userspace_addr;
+ spin_unlock(&kvm->mmu_lock);
} else {
if (!old.user_alloc && old.rmap) {
int ret;
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 4295623..a67e38f 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -298,7 +299,15 @@ int __kvm_set_memory_region(struct kvm *kvm,
memset(new.rmap, 0, npages * sizeof(*new.rmap));
new.user_alloc = user_alloc;
- new.userspace_addr = mem->userspace_addr;
+ /*
+ * hva_to_rmmap() serialzies with the mmu_lock and to be
+ * safe it has to ignore memslots with !user_alloc &&
+ * !userspace_addr.
+ */
+ if (user_alloc)
+ new.userspace_addr = mem->userspace_addr;
+ else
+ new.userspace_addr = 0;
}
/* Allocate page dirty bitmap if needed */
@@ -311,14 +320,18 @@ int __kvm_set_memory_region(struct kvm *kvm,
memset(new.dirty_bitmap, 0, dirty_bytes);
}
+ spin_lock(&kvm->mmu_lock);
if (mem->slot >= kvm->nmemslots)
kvm->nmemslots = mem->slot + 1;
*memslot = new;
+ spin_unlock(&kvm->mmu_lock);
r = kvm_arch_set_memory_region(kvm, mem, old, user_alloc);
if (r) {
+ spin_lock(&kvm->mmu_lock);
*memslot = old;
+ spin_unlock(&kvm->mmu_lock);
goto out_free;
}
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