KVM: MMU: Fix oopses with SLUB

The kvm mmu uses page->private on shadow page tables; so does slub, and
an oops result.  Fix by allocating regular pages for shadows instead of
using slub.

Tested-by: S.Çağlar Onur <caglar@pardus.org.tr>
Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 26 insertions, 13 deletions

diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c
index 48d28f1ff4a1..d99d2fe53dca 100644
--- a/drivers/kvm/mmu.c
+++ b/drivers/kvm/mmu.c
@@ -154,7 +154,6 @@ struct kvm_rmap_desc {
 
 static struct kmem_cache *pte_chain_cache;
 static struct kmem_cache *rmap_desc_cache;
-static struct kmem_cache *mmu_page_cache;
 static struct kmem_cache *mmu_page_header_cache;
 
 static int is_write_protection(struct kvm_vcpu *vcpu)
@@ -225,6 +224,29 @@ static void mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc)
                 kfree(mc->objects[--mc->nobjs]);
 }
 
+static int mmu_topup_memory_cache_page(struct kvm_mmu_memory_cache *cache,
+                                       int min, gfp_t gfp_flags)
+{
+        struct page *page;
+
+        if (cache->nobjs >= min)
+                return 0;
+        while (cache->nobjs < ARRAY_SIZE(cache->objects)) {
+                page = alloc_page(gfp_flags);
+                if (!page)
+                        return -ENOMEM;
+                set_page_private(page, 0);
+                cache->objects[cache->nobjs++] = page_address(page);
+        }
+        return 0;
+}
+
+static void mmu_free_memory_cache_page(struct kvm_mmu_memory_cache *mc)
+{
+        while (mc->nobjs)
+                __free_page(mc->objects[--mc->nobjs]);
+}
+
 static int __mmu_topup_memory_caches(struct kvm_vcpu *vcpu, gfp_t gfp_flags)
 {
         int r;
@@ -237,8 +259,7 @@ static int __mmu_topup_memory_caches(struct kvm_vcpu *vcpu, gfp_t gfp_flags)
                                    rmap_desc_cache, 1, gfp_flags);
         if (r)
                 goto out;
-        r = mmu_topup_memory_cache(&vcpu->mmu_page_cache,
-                                   mmu_page_cache, 4, gfp_flags);
+        r = mmu_topup_memory_cache_page(&vcpu->mmu_page_cache, 4, gfp_flags);
         if (r)
                 goto out;
         r = mmu_topup_memory_cache(&vcpu->mmu_page_header_cache,
@@ -266,7 +287,7 @@ static void mmu_free_memory_caches(struct kvm_vcpu *vcpu)
 {
         mmu_free_memory_cache(&vcpu->mmu_pte_chain_cache);
         mmu_free_memory_cache(&vcpu->mmu_rmap_desc_cache);
-        mmu_free_memory_cache(&vcpu->mmu_page_cache);
+        mmu_free_memory_cache_page(&vcpu->mmu_page_cache);
         mmu_free_memory_cache(&vcpu->mmu_page_header_cache);
 }
 
@@ -458,7 +479,7 @@ static void kvm_mmu_free_page(struct kvm *kvm,
 {
         ASSERT(is_empty_shadow_page(page_head->spt));
         list_del(&page_head->link);
-        kfree(page_head->spt);
+        __free_page(virt_to_page(page_head->spt));
         kfree(page_head);
         ++kvm->n_free_mmu_pages;
 }
@@ -1301,8 +1322,6 @@ void kvm_mmu_module_exit(void)
                 kmem_cache_destroy(pte_chain_cache);
         if (rmap_desc_cache)
                 kmem_cache_destroy(rmap_desc_cache);
-        if (mmu_page_cache)
-                kmem_cache_destroy(mmu_page_cache);
         if (mmu_page_header_cache)
                 kmem_cache_destroy(mmu_page_header_cache);
 }
@@ -1320,12 +1339,6 @@ int kvm_mmu_module_init(void)
         if (!rmap_desc_cache)
                 goto nomem;
 
-        mmu_page_cache = kmem_cache_create("kvm_mmu_page",
-                                           PAGE_SIZE,
-                                           PAGE_SIZE, 0, NULL);
-        if (!mmu_page_cache)
-                goto nomem;
-
         mmu_page_header_cache = kmem_cache_create("kvm_mmu_page_header",
                                                   sizeof(struct kvm_mmu_page),
                                                   0, 0, NULL);