[PATCH] KVM: MU: Special treatment for shadow pae root pages

Since we're not going to cache the pae-mode shadow root pages, allocate a
single pae shadow that will hold the four lower-level pages, which will act as
roots.

Signed-off-by: Avi Kivity <avi@qumranet.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 80 insertions, 30 deletions

diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c
index 0f27beb6c5df..1dcbbd511660 100644
--- a/drivers/kvm/mmu.c
+++ b/drivers/kvm/mmu.c
@@ -420,19 +420,63 @@ static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, hpa_t p)
         }
 }
 
+static void mmu_free_roots(struct kvm_vcpu *vcpu)
+{
+        int i;
+
+#ifdef CONFIG_X86_64
+        if (vcpu->mmu.shadow_root_level == PT64_ROOT_LEVEL) {
+                hpa_t root = vcpu->mmu.root_hpa;
+
+                ASSERT(VALID_PAGE(root));
+                release_pt_page_64(vcpu, root, PT64_ROOT_LEVEL);
+                vcpu->mmu.root_hpa = INVALID_PAGE;
+                return;
+        }
+#endif
+        for (i = 0; i < 4; ++i) {
+                hpa_t root = vcpu->mmu.pae_root[i];
+
+                ASSERT(VALID_PAGE(root));
+                root &= PT64_BASE_ADDR_MASK;
+                release_pt_page_64(vcpu, root, PT32E_ROOT_LEVEL - 1);
+                vcpu->mmu.pae_root[i] = INVALID_PAGE;
+        }
+        vcpu->mmu.root_hpa = INVALID_PAGE;
+}
+
+static void mmu_alloc_roots(struct kvm_vcpu *vcpu)
+{
+        int i;
+
+#ifdef CONFIG_X86_64
+        if (vcpu->mmu.shadow_root_level == PT64_ROOT_LEVEL) {
+                hpa_t root = vcpu->mmu.root_hpa;
+
+                ASSERT(!VALID_PAGE(root));
+                root = kvm_mmu_alloc_page(vcpu, NULL);
+                vcpu->mmu.root_hpa = root;
+                return;
+        }
+#endif
+        for (i = 0; i < 4; ++i) {
+                hpa_t root = vcpu->mmu.pae_root[i];
+
+                ASSERT(!VALID_PAGE(root));
+                root = kvm_mmu_alloc_page(vcpu, NULL);
+                vcpu->mmu.pae_root[i] = root | PT_PRESENT_MASK;
+        }
+        vcpu->mmu.root_hpa = __pa(vcpu->mmu.pae_root);
+}
+
 static void nonpaging_flush(struct kvm_vcpu *vcpu)
 {
         hpa_t root = vcpu->mmu.root_hpa;
 
         ++kvm_stat.tlb_flush;
         pgprintk("nonpaging_flush\n");
-        ASSERT(VALID_PAGE(root));
-        release_pt_page_64(vcpu, root, vcpu->mmu.shadow_root_level);
-        root = kvm_mmu_alloc_page(vcpu, NULL);
-        ASSERT(VALID_PAGE(root));
-        vcpu->mmu.root_hpa = root;
-        if (is_paging(vcpu))
-                root |= (vcpu->cr3 & (CR3_PCD_MASK | CR3_WPT_MASK));
+        mmu_free_roots(vcpu);
+        mmu_alloc_roots(vcpu);
         kvm_arch_ops->set_cr3(vcpu, root);
         kvm_arch_ops->tlb_flush(vcpu);
 }
@@ -475,13 +519,7 @@ static void nonpaging_inval_page(struct kvm_vcpu *vcpu, gva_t addr)
 
 static void nonpaging_free(struct kvm_vcpu *vcpu)
 {
-        hpa_t root;
-
-        ASSERT(vcpu);
-        root = vcpu->mmu.root_hpa;
-        if (VALID_PAGE(root))
-                release_pt_page_64(vcpu, root, vcpu->mmu.shadow_root_level);
-        vcpu->mmu.root_hpa = INVALID_PAGE;
+        mmu_free_roots(vcpu);
 }
 
 static int nonpaging_init_context(struct kvm_vcpu *vcpu)
@@ -495,7 +533,7 @@ static int nonpaging_init_context(struct kvm_vcpu *vcpu)
         context->free = nonpaging_free;
         context->root_level = PT32E_ROOT_LEVEL;
         context->shadow_root_level = PT32E_ROOT_LEVEL;
-        context->root_hpa = kvm_mmu_alloc_page(vcpu, NULL);
+        mmu_alloc_roots(vcpu);
         ASSERT(VALID_PAGE(context->root_hpa));
         kvm_arch_ops->set_cr3(vcpu, context->root_hpa);
         return 0;
@@ -647,7 +685,7 @@ static void paging_free(struct kvm_vcpu *vcpu)
 #include "paging_tmpl.h"
 #undef PTTYPE
 
-static int paging64_init_context(struct kvm_vcpu *vcpu)
+static int paging64_init_context_common(struct kvm_vcpu *vcpu, int level)
 {
         struct kvm_mmu *context = &vcpu->mmu;
 
@@ -657,15 +695,20 @@ static int paging64_init_context(struct kvm_vcpu *vcpu)
         context->inval_page = paging_inval_page;
         context->gva_to_gpa = paging64_gva_to_gpa;
         context->free = paging_free;
-        context->root_level = PT64_ROOT_LEVEL;
-        context->shadow_root_level = PT64_ROOT_LEVEL;
-        context->root_hpa = kvm_mmu_alloc_page(vcpu, NULL);
+        context->root_level = level;
+        context->shadow_root_level = level;
+        mmu_alloc_roots(vcpu);
         ASSERT(VALID_PAGE(context->root_hpa));
         kvm_arch_ops->set_cr3(vcpu, context->root_hpa |
                     (vcpu->cr3 & (CR3_PCD_MASK | CR3_WPT_MASK)));
         return 0;
 }
 
+static int paging64_init_context(struct kvm_vcpu *vcpu)
+{
+        return paging64_init_context_common(vcpu, PT64_ROOT_LEVEL);
+}
+
 static int paging32_init_context(struct kvm_vcpu *vcpu)
 {
         struct kvm_mmu *context = &vcpu->mmu;
@@ -677,7 +720,7 @@ static int paging32_init_context(struct kvm_vcpu *vcpu)
         context->free = paging_free;
         context->root_level = PT32_ROOT_LEVEL;
         context->shadow_root_level = PT32E_ROOT_LEVEL;
-        context->root_hpa = kvm_mmu_alloc_page(vcpu, NULL);
+        mmu_alloc_roots(vcpu);
         ASSERT(VALID_PAGE(context->root_hpa));
         kvm_arch_ops->set_cr3(vcpu, context->root_hpa |
                     (vcpu->cr3 & (CR3_PCD_MASK | CR3_WPT_MASK)));
@@ -686,14 +729,7 @@ static int paging32_init_context(struct kvm_vcpu *vcpu)
 
 static int paging32E_init_context(struct kvm_vcpu *vcpu)
 {
-        int ret;
-
-        if ((ret = paging64_init_context(vcpu)))
-                return ret;
-
-        vcpu->mmu.root_level = PT32E_ROOT_LEVEL;
-        vcpu->mmu.shadow_root_level = PT32E_ROOT_LEVEL;
-        return 0;
+        return paging64_init_context_common(vcpu, PT32E_ROOT_LEVEL);
 }
 
 static int init_kvm_mmu(struct kvm_vcpu *vcpu)
@@ -737,26 +773,40 @@ static void free_mmu_pages(struct kvm_vcpu *vcpu)
                 __free_page(pfn_to_page(page->page_hpa >> PAGE_SHIFT));
                 page->page_hpa = INVALID_PAGE;
         }
+        free_page((unsigned long)vcpu->mmu.pae_root);
 }
 
 static int alloc_mmu_pages(struct kvm_vcpu *vcpu)
 {
+        struct page *page;
         int i;
 
         ASSERT(vcpu);
 
         for (i = 0; i < KVM_NUM_MMU_PAGES; i++) {
-                struct page *page;
                 struct kvm_mmu_page *page_header = &vcpu->page_header_buf[i];
 
                 INIT_LIST_HEAD(&page_header->link);
-                if ((page = alloc_page(GFP_KVM_MMU)) == NULL)
+                if ((page = alloc_page(GFP_KERNEL)) == NULL)
                         goto error_1;
                 page->private = (unsigned long)page_header;
                 page_header->page_hpa = (hpa_t)page_to_pfn(page) << PAGE_SHIFT;
                 memset(__va(page_header->page_hpa), 0, PAGE_SIZE);
                 list_add(&page_header->link, &vcpu->free_pages);
         }
+
+        /*
+         * When emulating 32-bit mode, cr3 is only 32 bits even on x86_64.
+         * Therefore we need to allocate shadow page tables in the first
+         * 4GB of memory, which happens to fit the DMA32 zone.
+         */
+        page = alloc_page(GFP_KERNEL | __GFP_DMA32);
+        if (!page)
+                goto error_1;
+        vcpu->mmu.pae_root = page_address(page);
+        for (i = 0; i < 4; ++i)
+                vcpu->mmu.pae_root[i] = INVALID_PAGE;
+
         return 0;
 
 error_1: