1 files changed, 484 insertions, 0 deletions

diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
new file mode 100644
index 00000000000..03ba8608fe0
--- /dev/null
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -0,0 +1,484 @@
+/*
+ * Kernel-based Virtual Machine driver for Linux
+ *
+ * This module enables machines with Intel VT-x extensions to run virtual
+ * machines without emulation or binary translation.
+ *
+ * MMU support
+ *
+ * Copyright (C) 2006 Qumranet, Inc.
+ *
+ * Authors:
+ *   Yaniv Kamay  <yaniv@qumranet.com>
+ *   Avi Kivity   <avi@qumranet.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ */
+
+/*
+ * We need the mmu code to access both 32-bit and 64-bit guest ptes,
+ * so the code in this file is compiled twice, once per pte size.
+ */
+
+#if PTTYPE == 64
+	#define pt_element_t u64
+	#define guest_walker guest_walker64
+	#define FNAME(name) paging##64_##name
+	#define PT_BASE_ADDR_MASK PT64_BASE_ADDR_MASK
+	#define PT_DIR_BASE_ADDR_MASK PT64_DIR_BASE_ADDR_MASK
+	#define PT_INDEX(addr, level) PT64_INDEX(addr, level)
+	#define SHADOW_PT_INDEX(addr, level) PT64_INDEX(addr, level)
+	#define PT_LEVEL_MASK(level) PT64_LEVEL_MASK(level)
+	#define PT_LEVEL_BITS PT64_LEVEL_BITS
+	#ifdef CONFIG_X86_64
+	#define PT_MAX_FULL_LEVELS 4
+	#define CMPXCHG cmpxchg
+	#else
+	#define CMPXCHG cmpxchg64
+	#define PT_MAX_FULL_LEVELS 2
+	#endif
+#elif PTTYPE == 32
+	#define pt_element_t u32
+	#define guest_walker guest_walker32
+	#define FNAME(name) paging##32_##name
+	#define PT_BASE_ADDR_MASK PT32_BASE_ADDR_MASK
+	#define PT_DIR_BASE_ADDR_MASK PT32_DIR_BASE_ADDR_MASK
+	#define PT_INDEX(addr, level) PT32_INDEX(addr, level)
+	#define SHADOW_PT_INDEX(addr, level) PT64_INDEX(addr, level)
+	#define PT_LEVEL_MASK(level) PT32_LEVEL_MASK(level)
+	#define PT_LEVEL_BITS PT32_LEVEL_BITS
+	#define PT_MAX_FULL_LEVELS 2
+	#define CMPXCHG cmpxchg
+#else
+	#error Invalid PTTYPE value
+#endif
+
+#define gpte_to_gfn FNAME(gpte_to_gfn)
+#define gpte_to_gfn_pde FNAME(gpte_to_gfn_pde)
+
+/*
+ * The guest_walker structure emulates the behavior of the hardware page
+ * table walker.
+ */
+struct guest_walker {
+	int level;
+	gfn_t table_gfn[PT_MAX_FULL_LEVELS];
+	pt_element_t ptes[PT_MAX_FULL_LEVELS];
+	gpa_t pte_gpa[PT_MAX_FULL_LEVELS];
+	unsigned pt_access;
+	unsigned pte_access;
+	gfn_t gfn;
+	u32 error_code;
+};
+
+static gfn_t gpte_to_gfn(pt_element_t gpte)
+{
+	return (gpte & PT_BASE_ADDR_MASK) >> PAGE_SHIFT;
+}
+
+static gfn_t gpte_to_gfn_pde(pt_element_t gpte)
+{
+	return (gpte & PT_DIR_BASE_ADDR_MASK) >> PAGE_SHIFT;
+}
+
+static bool FNAME(cmpxchg_gpte)(struct kvm *kvm,
+			 gfn_t table_gfn, unsigned index,
+			 pt_element_t orig_pte, pt_element_t new_pte)
+{
+	pt_element_t ret;
+	pt_element_t *table;
+	struct page *page;
+
+	page = gfn_to_page(kvm, table_gfn);
+	table = kmap_atomic(page, KM_USER0);
+
+	ret = CMPXCHG(&table[index], orig_pte, new_pte);
+
+	kunmap_atomic(table, KM_USER0);
+
+	kvm_release_page_dirty(page);
+
+	return (ret != orig_pte);
+}
+
+static unsigned FNAME(gpte_access)(struct kvm_vcpu *vcpu, pt_element_t gpte)
+{
+	unsigned access;
+
+	access = (gpte & (PT_WRITABLE_MASK | PT_USER_MASK)) | ACC_EXEC_MASK;
+#if PTTYPE == 64
+	if (is_nx(vcpu))
+		access &= ~(gpte >> PT64_NX_SHIFT);
+#endif
+	return access;
+}
+
+/*
+ * Fetch a guest pte for a guest virtual address
+ */
+static int FNAME(walk_addr)(struct guest_walker *walker,
+			    struct kvm_vcpu *vcpu, gva_t addr,
+			    int write_fault, int user_fault, int fetch_fault)
+{
+	pt_element_t pte;
+	gfn_t table_gfn;
+	unsigned index, pt_access, pte_access;
+	gpa_t pte_gpa;
+
+	pgprintk("%s: addr %lx\n", __FUNCTION__, addr);
+walk:
+	walker->level = vcpu->arch.mmu.root_level;
+	pte = vcpu->arch.cr3;
+#if PTTYPE == 64
+	if (!is_long_mode(vcpu)) {
+		pte = vcpu->arch.pdptrs[(addr >> 30) & 3];
+		if (!is_present_pte(pte))
+			goto not_present;
+		--walker->level;
+	}
+#endif
+	ASSERT((!is_long_mode(vcpu) && is_pae(vcpu)) ||
+	       (vcpu->cr3 & CR3_NONPAE_RESERVED_BITS) == 0);
+
+	pt_access = ACC_ALL;
+
+	for (;;) {
+		index = PT_INDEX(addr, walker->level);
+
+		table_gfn = gpte_to_gfn(pte);
+		pte_gpa = gfn_to_gpa(table_gfn);
+		pte_gpa += index * sizeof(pt_element_t);
+		walker->table_gfn[walker->level - 1] = table_gfn;
+		walker->pte_gpa[walker->level - 1] = pte_gpa;
+		pgprintk("%s: table_gfn[%d] %lx\n", __FUNCTION__,
+			 walker->level - 1, table_gfn);
+
+		kvm_read_guest(vcpu->kvm, pte_gpa, &pte, sizeof(pte));
+
+		if (!is_present_pte(pte))
+			goto not_present;
+
+		if (write_fault && !is_writeble_pte(pte))
+			if (user_fault || is_write_protection(vcpu))
+				goto access_error;
+
+		if (user_fault && !(pte & PT_USER_MASK))
+			goto access_error;
+
+#if PTTYPE == 64
+		if (fetch_fault && is_nx(vcpu) && (pte & PT64_NX_MASK))
+			goto access_error;
+#endif
+
+		if (!(pte & PT_ACCESSED_MASK)) {
+			mark_page_dirty(vcpu->kvm, table_gfn);
+			if (FNAME(cmpxchg_gpte)(vcpu->kvm, table_gfn,
+			    index, pte, pte|PT_ACCESSED_MASK))
+				goto walk;
+			pte |= PT_ACCESSED_MASK;
+		}
+
+		pte_access = pt_access & FNAME(gpte_access)(vcpu, pte);
+
+		walker->ptes[walker->level - 1] = pte;
+
+		if (walker->level == PT_PAGE_TABLE_LEVEL) {
+			walker->gfn = gpte_to_gfn(pte);
+			break;
+		}
+
+		if (walker->level == PT_DIRECTORY_LEVEL
+		    && (pte & PT_PAGE_SIZE_MASK)
+		    && (PTTYPE == 64 || is_pse(vcpu))) {
+			walker->gfn = gpte_to_gfn_pde(pte);
+			walker->gfn += PT_INDEX(addr, PT_PAGE_TABLE_LEVEL);
+			if (PTTYPE == 32 && is_cpuid_PSE36())
+				walker->gfn += pse36_gfn_delta(pte);
+			break;
+		}
+
+		pt_access = pte_access;
+		--walker->level;
+	}
+
+	if (write_fault && !is_dirty_pte(pte)) {
+		bool ret;
+
+		mark_page_dirty(vcpu->kvm, table_gfn);
+		ret = FNAME(cmpxchg_gpte)(vcpu->kvm, table_gfn, index, pte,
+			    pte|PT_DIRTY_MASK);
+		if (ret)
+			goto walk;
+		pte |= PT_DIRTY_MASK;
+		kvm_mmu_pte_write(vcpu, pte_gpa, (u8 *)&pte, sizeof(pte));
+		walker->ptes[walker->level - 1] = pte;
+	}
+
+	walker->pt_access = pt_access;
+	walker->pte_access = pte_access;
+	pgprintk("%s: pte %llx pte_access %x pt_access %x\n",
+		 __FUNCTION__, (u64)pte, pt_access, pte_access);
+	return 1;
+
+not_present:
+	walker->error_code = 0;
+	goto err;
+
+access_error:
+	walker->error_code = PFERR_PRESENT_MASK;
+
+err:
+	if (write_fault)
+		walker->error_code |= PFERR_WRITE_MASK;
+	if (user_fault)
+		walker->error_code |= PFERR_USER_MASK;
+	if (fetch_fault)
+		walker->error_code |= PFERR_FETCH_MASK;
+	return 0;
+}
+
+static void FNAME(update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *page,
+			      u64 *spte, const void *pte, int bytes,
+			      int offset_in_pte)
+{
+	pt_element_t gpte;
+	unsigned pte_access;
+	struct page *npage;
+
+	gpte = *(const pt_element_t *)pte;
+	if (~gpte & (PT_PRESENT_MASK | PT_ACCESSED_MASK)) {
+		if (!offset_in_pte && !is_present_pte(gpte))
+			set_shadow_pte(spte, shadow_notrap_nonpresent_pte);
+		return;
+	}
+	if (bytes < sizeof(pt_element_t))
+		return;
+	pgprintk("%s: gpte %llx spte %p\n", __FUNCTION__, (u64)gpte, spte);
+	pte_access = page->role.access & FNAME(gpte_access)(vcpu, gpte);
+	if (gpte_to_gfn(gpte) != vcpu->arch.update_pte.gfn)
+		return;
+	npage = vcpu->arch.update_pte.page;
+	if (!npage)
+		return;
+	get_page(npage);
+	mmu_set_spte(vcpu, spte, page->role.access, pte_access, 0, 0,
+		     gpte & PT_DIRTY_MASK, NULL, gpte_to_gfn(gpte), npage);
+}
+
+/*
+ * Fetch a shadow pte for a specific level in the paging hierarchy.
+ */
+static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
+			 struct guest_walker *walker,
+			 int user_fault, int write_fault, int *ptwrite,
+			 struct page *page)
+{
+	hpa_t shadow_addr;
+	int level;
+	u64 *shadow_ent;
+	unsigned access = walker->pt_access;
+
+	if (!is_present_pte(walker->ptes[walker->level - 1]))
+		return NULL;
+
+	shadow_addr = vcpu->arch.mmu.root_hpa;
+	level = vcpu->arch.mmu.shadow_root_level;
+	if (level == PT32E_ROOT_LEVEL) {
+		shadow_addr = vcpu->arch.mmu.pae_root[(addr >> 30) & 3];
+		shadow_addr &= PT64_BASE_ADDR_MASK;
+		--level;
+	}
+
+	for (; ; level--) {
+		u32 index = SHADOW_PT_INDEX(addr, level);
+		struct kvm_mmu_page *shadow_page;
+		u64 shadow_pte;
+		int metaphysical;
+		gfn_t table_gfn;
+		bool new_page = 0;
+
+		shadow_ent = ((u64 *)__va(shadow_addr)) + index;
+		if (level == PT_PAGE_TABLE_LEVEL)
+			break;
+		if (is_shadow_present_pte(*shadow_ent)) {
+			shadow_addr = *shadow_ent & PT64_BASE_ADDR_MASK;
+			continue;
+		}
+
+		if (level - 1 == PT_PAGE_TABLE_LEVEL
+		    && walker->level == PT_DIRECTORY_LEVEL) {
+			metaphysical = 1;
+			if (!is_dirty_pte(walker->ptes[level - 1]))
+				access &= ~ACC_WRITE_MASK;
+			table_gfn = gpte_to_gfn(walker->ptes[level - 1]);
+		} else {
+			metaphysical = 0;
+			table_gfn = walker->table_gfn[level - 2];
+		}
+		shadow_page = kvm_mmu_get_page(vcpu, table_gfn, addr, level-1,
+					       metaphysical, access,
+					       shadow_ent, &new_page);
+		if (new_page && !metaphysical) {
+			int r;
+			pt_element_t curr_pte;
+			r = kvm_read_guest_atomic(vcpu->kvm,
+						  walker->pte_gpa[level - 2],
+						  &curr_pte, sizeof(curr_pte));
+			if (r || curr_pte != walker->ptes[level - 2]) {
+				kvm_release_page_clean(page);
+				return NULL;
+			}
+		}
+		shadow_addr = __pa(shadow_page->spt);
+		shadow_pte = shadow_addr | PT_PRESENT_MASK | PT_ACCESSED_MASK
+			| PT_WRITABLE_MASK | PT_USER_MASK;
+		*shadow_ent = shadow_pte;
+	}
+
+	mmu_set_spte(vcpu, shadow_ent, access, walker->pte_access & access,
+		     user_fault, write_fault,
+		     walker->ptes[walker->level-1] & PT_DIRTY_MASK,
+		     ptwrite, walker->gfn, page);
+
+	return shadow_ent;
+}
+
+/*
+ * Page fault handler.  There are several causes for a page fault:
+ *   - there is no shadow pte for the guest pte
+ *   - write access through a shadow pte marked read only so that we can set
+ *     the dirty bit
+ *   - write access to a shadow pte marked read only so we can update the page
+ *     dirty bitmap, when userspace requests it
+ *   - mmio access; in this case we will never install a present shadow pte
+ *   - normal guest page fault due to the guest pte marked not present, not
+ *     writable, or not executable
+ *
+ *  Returns: 1 if we need to emulate the instruction, 0 otherwise, or
+ *           a negative value on error.
+ */
+static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
+			       u32 error_code)
+{
+	int write_fault = error_code & PFERR_WRITE_MASK;
+	int user_fault = error_code & PFERR_USER_MASK;
+	int fetch_fault = error_code & PFERR_FETCH_MASK;
+	struct guest_walker walker;
+	u64 *shadow_pte;
+	int write_pt = 0;
+	int r;
+	struct page *page;
+
+	pgprintk("%s: addr %lx err %x\n", __FUNCTION__, addr, error_code);
+	kvm_mmu_audit(vcpu, "pre page fault");
+
+	r = mmu_topup_memory_caches(vcpu);
+	if (r)
+		return r;
+
+	down_read(&current->mm->mmap_sem);
+	/*
+	 * Look up the shadow pte for the faulting address.
+	 */
+	r = FNAME(walk_addr)(&walker, vcpu, addr, write_fault, user_fault,
+			     fetch_fault);
+
+	/*
+	 * The page is not mapped by the guest.  Let the guest handle it.
+	 */
+	if (!r) {
+		pgprintk("%s: guest page fault\n", __FUNCTION__);
+		inject_page_fault(vcpu, addr, walker.error_code);
+		vcpu->arch.last_pt_write_count = 0; /* reset fork detector */
+		up_read(&current->mm->mmap_sem);
+		return 0;
+	}
+
+	page = gfn_to_page(vcpu->kvm, walker.gfn);
+
+	spin_lock(&vcpu->kvm->mmu_lock);
+	kvm_mmu_free_some_pages(vcpu);
+	shadow_pte = FNAME(fetch)(vcpu, addr, &walker, user_fault, write_fault,
+				  &write_pt, page);
+	pgprintk("%s: shadow pte %p %llx ptwrite %d\n", __FUNCTION__,
+		 shadow_pte, *shadow_pte, write_pt);
+
+	if (!write_pt)
+		vcpu->arch.last_pt_write_count = 0; /* reset fork detector */
+
+	/*
+	 * mmio: emulate if accessible, otherwise its a guest fault.
+	 */
+	if (shadow_pte && is_io_pte(*shadow_pte)) {
+		spin_unlock(&vcpu->kvm->mmu_lock);
+		up_read(&current->mm->mmap_sem);
+		return 1;
+	}
+
+	++vcpu->stat.pf_fixed;
+	kvm_mmu_audit(vcpu, "post page fault (fixed)");
+	spin_unlock(&vcpu->kvm->mmu_lock);
+	up_read(&current->mm->mmap_sem);
+
+	return write_pt;
+}
+
+static gpa_t FNAME(gva_to_gpa)(struct kvm_vcpu *vcpu, gva_t vaddr)
+{
+	struct guest_walker walker;
+	gpa_t gpa = UNMAPPED_GVA;
+	int r;
+
+	r = FNAME(walk_addr)(&walker, vcpu, vaddr, 0, 0, 0);
+
+	if (r) {
+		gpa = gfn_to_gpa(walker.gfn);
+		gpa |= vaddr & ~PAGE_MASK;
+	}
+
+	return gpa;
+}
+
+static void FNAME(prefetch_page)(struct kvm_vcpu *vcpu,
+				 struct kvm_mmu_page *sp)
+{
+	int i, offset = 0, r = 0;
+	pt_element_t pt;
+
+	if (sp->role.metaphysical
+	    || (PTTYPE == 32 && sp->role.level > PT_PAGE_TABLE_LEVEL)) {
+		nonpaging_prefetch_page(vcpu, sp);
+		return;
+	}
+
+	if (PTTYPE == 32)
+		offset = sp->role.quadrant << PT64_LEVEL_BITS;
+
+	for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {
+		gpa_t pte_gpa = gfn_to_gpa(sp->gfn);
+		pte_gpa += (i+offset) * sizeof(pt_element_t);
+
+		r = kvm_read_guest_atomic(vcpu->kvm, pte_gpa, &pt,
+					  sizeof(pt_element_t));
+		if (r || is_present_pte(pt))
+			sp->spt[i] = shadow_trap_nonpresent_pte;
+		else
+			sp->spt[i] = shadow_notrap_nonpresent_pte;
+	}
+}
+
+#undef pt_element_t
+#undef guest_walker
+#undef FNAME
+#undef PT_BASE_ADDR_MASK
+#undef PT_INDEX
+#undef SHADOW_PT_INDEX
+#undef PT_LEVEL_MASK
+#undef PT_DIR_BASE_ADDR_MASK
+#undef PT_LEVEL_BITS
+#undef PT_MAX_FULL_LEVELS
+#undef gpte_to_gfn
+#undef gpte_to_gfn_pde
+#undef CMPXCHG