[PATCH 5/33] KVM: MU: Special treatment for shadow pae root pages

Avi Kivity
2007-01-04T15:54:11Z

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>

Index: linux-2.6/drivers/kvm/mmu.c
===================================================================
--- linux-2.6.orig/drivers/kvm/mmu.c
+++ linux-2.6/drivers/kvm/mmu.c
@@ -420,19 +420,63 @@ static int nonpaging_map(struct kvm_vcpu
}
}

+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

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
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
#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
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
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

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_vc
__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:
Index: linux-2.6/drivers/kvm/kvm.h
===================================================================
--- linux-2.6.orig/drivers/kvm/kvm.h
+++ linux-2.6/drivers/kvm/kvm.h
@@ -123,6 +123,8 @@ struct kvm_mmu {
hpa_t root_hpa;
int root_level;
int shadow_root_level;
+
+ u64 *pae_root;
};

struct kvm_guest_debug {
@@ -548,19 +550,4 @@ static inline u32 get_rdx_init_val(void)
#define TSS_REDIRECTION_SIZE (256 / 8)
#define RMODE_TSS_SIZE (TSS_BASE_SIZE + TSS_REDIRECTION_SIZE + TSS_IOPB_SIZE + 1)

-#ifdef CONFIG_X86_64
-
-/*
- * 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.
- */
-#define GFP_KVM_MMU (GFP_KERNEL | __GFP_DMA32)
-
-#else
-
-#define GFP_KVM_MMU GFP_KERNEL
-
-#endif
-
#endif