RE: [PATCH v10 07/14] KVM: ARM: Memory virtualization setup

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Dear Christoffer Dall,

In you code, kvm_alloc_stage2_pgd function allocates page table and memset.
isn't it necessary to clean the data cache after memset?

For reference, pgd_alloc cleans the area with clean_dcache_area.

There's some situation that cleaning is not necessary, and clean_dcache_area function becomes empty in that case.
But I think explicit cleaning would be better for portability.


Best Regards
Min-gyu Kim


-----Original Message-----
From: kvm-owner@xxxxxxxxxxxxxxx [mailto:kvm-owner@xxxxxxxxxxxxxxx] On Behalf Of Christoffer Dall
Sent: Friday, August 17, 2012 12:29 AM
To: kvmarm@xxxxxxxxxxxxxxxxxxxxx; kvm@xxxxxxxxxxxxxxx
Subject: [PATCH v10 07/14] KVM: ARM: Memory virtualization setup

This commit introduces the framework for guest memory management through the use of 2nd stage translation. Each VM has a pointer to a level-1 table (the pgd field in struct kvm_arch) which is used for the 2nd stage translations. Entries are added when handling guest faults (later patch) and the table itself can be allocated and freed through the following functions implemented in
arch/arm/kvm/arm_mmu.c:
 - kvm_alloc_stage2_pgd(struct kvm *kvm);
 - kvm_free_stage2_pgd(struct kvm *kvm);

Introduces new ARM-specific kernel memory types, PAGE_KVM_GUEST and pgprot_guest variables used to map 2nd stage memory for KVM guests.

Each entry in TLBs and caches are tagged with a VMID identifier in addition to ASIDs. The VMIDs are assigned consecutively to VMs in the order that VMs are executed, and caches and tlbs are invalidated when the VMID space has been used to allow for more than 255 simultaenously running guests.

The 2nd stage pgd is allocated in kvm_arch_init_vm(). The table is freed in kvm_arch_destroy_vm(). Both functions are called from the main KVM code.

We pre-allocate page table memory to be able to synchronize using a spinlock and be called under rcu_read_lock from the MMU notifiers.  We steal the mmu_memory_cache implementation from x86 and adapt for our specific usage.

We support MMU notifiers (thanks to Marc Zyngier) through kvm_unmap_hva and kvm_set_spte_hva.

Finally, define kvm_phys_addr_ioremap() to map a device at a guest IPA, which is used by VGIC support to map the virtual CPU interface registers to the guest. This support is added by Marc Zyngier.

Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
Signed-off-by: Christoffer Dall <c.dall@xxxxxxxxxxxxxxxxxxxxxx>
---
 arch/arm/include/asm/kvm_asm.h        |    2 
 arch/arm/include/asm/kvm_host.h       |   18 ++
 arch/arm/include/asm/kvm_mmu.h        |    9 +
 arch/arm/include/asm/pgtable-3level.h |    9 +
 arch/arm/include/asm/pgtable.h        |    4 
 arch/arm/kvm/Kconfig                  |    1 
 arch/arm/kvm/arm.c                    |   38 +++
 arch/arm/kvm/exports.c                |    1 
 arch/arm/kvm/interrupts.S             |    8 +
 arch/arm/kvm/mmu.c                    |  373 +++++++++++++++++++++++++++++++++
 arch/arm/mm/mmu.c                     |    3 
 11 files changed, 465 insertions(+), 1 deletion(-)

diff --git a/arch/arm/include/asm/kvm_asm.h b/arch/arm/include/asm/kvm_asm.h index 58d51e3..55b6446 100644
--- a/arch/arm/include/asm/kvm_asm.h
+++ b/arch/arm/include/asm/kvm_asm.h
@@ -34,6 +34,7 @@
 #define SMCHYP_HVBAR_W 0xfffffff0
 
 #ifndef __ASSEMBLY__
+struct kvm;
 struct kvm_vcpu;
 
 extern char __kvm_hyp_init[];
@@ -48,6 +49,7 @@ extern char __kvm_hyp_code_start[];  extern char __kvm_hyp_code_end[];
 
 extern void __kvm_flush_vm_context(void);
+extern void __kvm_tlb_flush_vmid(struct kvm *kvm);
 
 extern int __kvm_vcpu_run(struct kvm_vcpu *vcpu);  #endif diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h index d7e3398..d86ce39 100644
--- a/arch/arm/include/asm/kvm_host.h
+++ b/arch/arm/include/asm/kvm_host.h
@@ -157,4 +157,22 @@ struct kvm_vcpu_stat {  struct kvm_vcpu_init;  int kvm_vcpu_set_target(struct kvm_vcpu *vcpu,
 			const struct kvm_vcpu_init *init);
+
+#define KVM_ARCH_WANT_MMU_NOTIFIER
+struct kvm;
+int kvm_unmap_hva(struct kvm *kvm, unsigned long hva); int 
+kvm_unmap_hva_range(struct kvm *kvm,
+			unsigned long start, unsigned long end); void 
+kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte);
+
+/* We do not have shadow page tables, hence the empty hooks */ static 
+inline int kvm_age_hva(struct kvm *kvm, unsigned long hva) {
+	return 0;
+}
+
+static inline int kvm_test_age_hva(struct kvm *kvm, unsigned long hva) 
+{
+	return 0;
+}
 #endif /* __ARM_KVM_HOST_H__ */
diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h index 8252921..11f4c3a 100644
--- a/arch/arm/include/asm/kvm_mmu.h
+++ b/arch/arm/include/asm/kvm_mmu.h
@@ -33,4 +33,13 @@ int create_hyp_mappings(void *from, void *to);  int create_hyp_io_mappings(void *from, void *to, phys_addr_t);  void free_hyp_pmds(void);
 
+int kvm_alloc_stage2_pgd(struct kvm *kvm); void 
+kvm_free_stage2_pgd(struct kvm *kvm); int kvm_phys_addr_ioremap(struct 
+kvm *kvm, phys_addr_t guest_ipa,
+			  phys_addr_t pa, unsigned long size);
+
+int kvm_handle_guest_abort(struct kvm_vcpu *vcpu, struct kvm_run *run);
+
+void kvm_mmu_free_memory_caches(struct kvm_vcpu *vcpu);
+
 #endif /* __ARM_KVM_MMU_H__ */
diff --git a/arch/arm/include/asm/pgtable-3level.h b/arch/arm/include/asm/pgtable-3level.h
index 1169a8a..7351eee 100644
--- a/arch/arm/include/asm/pgtable-3level.h
+++ b/arch/arm/include/asm/pgtable-3level.h
@@ -102,6 +102,15 @@
  */
 #define L_PGD_SWAPPER		(_AT(pgdval_t, 1) << 55)	/* swapper_pg_dir entry */
 
+/*
+ * 2-nd stage PTE definitions for LPAE.
+ */
+#define L_PTE2_SHARED		L_PTE_SHARED
+#define L_PTE2_READ		(_AT(pteval_t, 1) << 6)	/* HAP[0] */
+#define L_PTE2_WRITE		(_AT(pteval_t, 1) << 7)	/* HAP[1] */
+#define L_PTE2_NORM_WB		(_AT(pteval_t, 3) << 4)	/* MemAttr[3:2] */
+#define L_PTE2_INNER_WB		(_AT(pteval_t, 3) << 2)	/* MemAttr[1:0] */
+
 #ifndef __ASSEMBLY__
 
 #define pud_none(pud)		(!pud_val(pud))
diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h index bc83540..a31d0e9 100644
--- a/arch/arm/include/asm/pgtable.h
+++ b/arch/arm/include/asm/pgtable.h
@@ -70,6 +70,7 @@ extern void __pgd_error(const char *file, int line, pgd_t);
 
 extern pgprot_t		pgprot_user;
 extern pgprot_t		pgprot_kernel;
+extern pgprot_t		pgprot_guest;
 
 #define _MOD_PROT(p, b)	__pgprot(pgprot_val(p) | (b))
 
@@ -83,6 +84,9 @@ extern pgprot_t		pgprot_kernel;
 #define PAGE_KERNEL		_MOD_PROT(pgprot_kernel, L_PTE_XN)
 #define PAGE_KERNEL_EXEC	pgprot_kernel
 #define PAGE_HYP		_MOD_PROT(pgprot_kernel, L_PTE_USER)
+#define PAGE_KVM_GUEST		_MOD_PROT(pgprot_guest, L_PTE2_READ | \
+					  L_PTE2_NORM_WB | L_PTE2_INNER_WB | \
+					  L_PTE2_SHARED)
 
 #define __PAGE_NONE		__pgprot(_L_PTE_DEFAULT | L_PTE_RDONLY | L_PTE_XN)
 #define __PAGE_SHARED		__pgprot(_L_PTE_DEFAULT | L_PTE_USER | L_PTE_XN)
diff --git a/arch/arm/kvm/Kconfig b/arch/arm/kvm/Kconfig index 83abbe0..7fa50d3 100644
--- a/arch/arm/kvm/Kconfig
+++ b/arch/arm/kvm/Kconfig
@@ -36,6 +36,7 @@ config KVM_ARM_HOST
 	depends on KVM
 	depends on MMU
 	depends on CPU_V7 && ARM_VIRT_EXT
+	select	MMU_NOTIFIER
 	---help---
 	  Provides host support for ARM processors.
 
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c index 0b1c466..3f97e7c 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -82,12 +82,34 @@ void kvm_arch_sync_events(struct kvm *kvm)  {  }
 
+/**
+ * kvm_arch_init_vm - initializes a VM data structure
+ * @kvm:	pointer to the KVM struct
+ */
 int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)  {
+	int ret = 0;
+
 	if (type)
 		return -EINVAL;
 
-	return 0;
+	ret = kvm_alloc_stage2_pgd(kvm);
+	if (ret)
+		goto out_fail_alloc;
+	spin_lock_init(&kvm->arch.pgd_lock);
+
+	ret = create_hyp_mappings(kvm, kvm + 1);
+	if (ret)
+		goto out_free_stage2_pgd;
+
+	/* Mark the initial VMID generation invalid */
+	kvm->arch.vmid_gen = 0;
+
+	return ret;
+out_free_stage2_pgd:
+	kvm_free_stage2_pgd(kvm);
+out_fail_alloc:
+	return ret;
 }
 
 int kvm_arch_vcpu_fault(struct kvm_vcpu *vcpu, struct vm_fault *vmf) @@ -105,10 +127,16 @@ int kvm_arch_create_memslot(struct kvm_memory_slot *slot, unsigned long npages)
 	return 0;
 }
 
+/**
+ * kvm_arch_destroy_vm - destroy the VM data structure
+ * @kvm:	pointer to the KVM struct
+ */
 void kvm_arch_destroy_vm(struct kvm *kvm)  {
 	int i;
 
+	kvm_free_stage2_pgd(kvm);
+
 	for (i = 0; i < KVM_MAX_VCPUS; ++i) {
 		if (kvm->vcpus[i]) {
 			kvm_arch_vcpu_free(kvm->vcpus[i]);
@@ -184,7 +212,13 @@ struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm, unsigned int id)
 	if (err)
 		goto free_vcpu;
 
+	err = create_hyp_mappings(vcpu, vcpu + 1);
+	if (err)
+		goto vcpu_uninit;
+
 	return vcpu;
+vcpu_uninit:
+	kvm_vcpu_uninit(vcpu);
 free_vcpu:
 	kmem_cache_free(kvm_vcpu_cache, vcpu);
 out:
@@ -193,6 +227,8 @@ out:
 
 void kvm_arch_vcpu_free(struct kvm_vcpu *vcpu)  {
+	kvm_mmu_free_memory_caches(vcpu);
+	kmem_cache_free(kvm_vcpu_cache, vcpu);
 }
 
 void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu) diff --git a/arch/arm/kvm/exports.c b/arch/arm/kvm/exports.c index 8ebdf07..f39f823 100644
--- a/arch/arm/kvm/exports.c
+++ b/arch/arm/kvm/exports.c
@@ -33,5 +33,6 @@ EXPORT_SYMBOL_GPL(__kvm_hyp_code_end);
 EXPORT_SYMBOL_GPL(__kvm_vcpu_run);
 
 EXPORT_SYMBOL_GPL(__kvm_flush_vm_context);
+EXPORT_SYMBOL_GPL(__kvm_tlb_flush_vmid);
 
 EXPORT_SYMBOL_GPL(smp_send_reschedule);
diff --git a/arch/arm/kvm/interrupts.S b/arch/arm/kvm/interrupts.S index bf09801..edf9ed5 100644
--- a/arch/arm/kvm/interrupts.S
+++ b/arch/arm/kvm/interrupts.S
@@ -31,6 +31,14 @@ __kvm_hyp_code_start:
 	.globl __kvm_hyp_code_start
 
 @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
+@  Flush per-VMID TLBs
+@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
+
+ENTRY(__kvm_tlb_flush_vmid)
+	bx	lr
+ENDPROC(__kvm_tlb_flush_vmid)
+
+@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
 @  Flush TLBs and instruction caches of current CPU for all VMIDs  @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
 
diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c index 6a7dfd4..6cb0e38 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -23,10 +23,43 @@
 #include <asm/pgalloc.h>
 #include <asm/kvm_arm.h>
 #include <asm/kvm_mmu.h>
+#include <asm/kvm_asm.h>
 #include <asm/mach/map.h>
 
 static DEFINE_MUTEX(kvm_hyp_pgd_mutex);
 
+static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *cache,
+				  int min, int max)
+{
+	void *page;
+
+	BUG_ON(max > KVM_NR_MEM_OBJS);
+	if (cache->nobjs >= min)
+		return 0;
+	while (cache->nobjs < max) {
+		page = (void *)__get_free_page(PGALLOC_GFP);
+		if (!page)
+			return -ENOMEM;
+		cache->objects[cache->nobjs++] = page;
+	}
+	return 0;
+}
+
+static void mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc) {
+	while (mc->nobjs)
+		free_page((unsigned long)mc->objects[--mc->nobjs]); }
+
+static void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc) {
+	void *p;
+
+	BUG_ON(!mc || !mc->nobjs);
+	p = mc->objects[--mc->nobjs];
+	return p;
+}
+
 static void free_ptes(pmd_t *pmd, unsigned long addr)  {
 	pte_t *pte;
@@ -200,7 +233,347 @@ int create_hyp_io_mappings(void *from, void *to, phys_addr_t addr)
 	return __create_hyp_mappings(from, to, &pfn);  }
 
+/**
+ * kvm_alloc_stage2_pgd - allocate level-1 table for stage-2 translation.
+ * @kvm:	The KVM struct pointer for the VM.
+ *
+ * Allocates the 1st level table only of size defined by PGD2_ORDER 
+(can
+ * support either full 40-bit input addresses or limited to 32-bit 
+input
+ * addresses). Clears the allocated pages.
+ *
+ * Note we don't need locking here as this is only called when the VM 
+is
+ * created, which can only be done once.
+ */
+int kvm_alloc_stage2_pgd(struct kvm *kvm) {
+	pgd_t *pgd;
+
+	if (kvm->arch.pgd != NULL) {
+		kvm_err("kvm_arch already initialized?\n");
+		return -EINVAL;
+	}
+
+	pgd = (pgd_t *)__get_free_pages(GFP_KERNEL, PGD2_ORDER);
+	if (!pgd)
+		return -ENOMEM;
+
+	memset(pgd, 0, PTRS_PER_PGD2 * sizeof(pgd_t));
+	kvm->arch.pgd = pgd;
+
+	return 0;
+}
+
+static void free_guest_pages(pte_t *pte, unsigned long addr) {
+	unsigned int i;
+	struct page *page, *pte_page;
+
+	pte_page = virt_to_page(pte);
+
+	for (i = 0; i < PTRS_PER_PTE; i++) {
+		if (pte_present(*pte)) {
+			unsigned long pfn = pte_pfn(*pte);
+
+			if (pfn_valid(pfn)) { /* Skip over device memory */
+				page = pfn_to_page(pfn);
+				put_page(page);
+			}
+			put_page(pte_page);
+		}
+		pte++;
+	}
+}
+
+static void free_stage2_ptes(pmd_t *pmd, unsigned long addr) {
+	unsigned int i;
+	pte_t *pte;
+	struct page *page, *pmd_page;
+
+	pmd_page = virt_to_page(pmd);
+
+	for (i = 0; i < PTRS_PER_PMD; i++, addr += PMD_SIZE) {
+		BUG_ON(pmd_sect(*pmd));
+		if (!pmd_none(*pmd) && pmd_table(*pmd)) {
+			pte = pte_offset_kernel(pmd, addr);
+			free_guest_pages(pte, addr);
+			page = virt_to_page((void *)pte);
+			WARN_ON(page_count(page) != 1);
+			pte_free_kernel(NULL, pte);
+
+			put_page(pmd_page);
+		}
+		pmd++;
+	}
+}
+
+/**
+ * kvm_free_stage2_pgd - free all stage-2 tables
+ * @kvm:	The KVM struct pointer for the VM.
+ *
+ * Walks the level-1 page table pointed to by kvm->arch.pgd and frees 
+all
+ * underlying level-2 and level-3 tables before freeing the actual 
+level-1 table
+ * and setting the struct pointer to NULL.
+ *
+ * Note we don't need locking here as this is only called when the VM 
+is
+ * destroyed, which can only be done once.
+ */
+void kvm_free_stage2_pgd(struct kvm *kvm) {
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd;
+	unsigned long long i, addr;
+	struct page *page, *pud_page;
+
+	if (kvm->arch.pgd == NULL)
+		return;
+
+	/*
+	 * We do this slightly different than other places, since we need more
+	 * than 32 bits and for instance pgd_addr_end converts to unsigned long.
+	 */
+	addr = 0;
+	for (i = 0; i < PTRS_PER_PGD2; i++) {
+		addr = i * (unsigned long long)PGDIR_SIZE;
+		pgd = kvm->arch.pgd + i;
+		pud = pud_offset(pgd, addr);
+		pud_page = virt_to_page(pud);
+
+		if (pud_none(*pud))
+			continue;
+
+		BUG_ON(pud_bad(*pud));
+
+		pmd = pmd_offset(pud, addr);
+		free_stage2_ptes(pmd, addr);
+		page = virt_to_page((void *)pmd);
+		WARN_ON(page_count(page) != 1);
+		pmd_free(NULL, pmd);
+		put_page(pud_page);
+	}
+
+	WARN_ON(page_count(pud_page) != 1);
+	free_pages((unsigned long)kvm->arch.pgd, PGD2_ORDER);
+	kvm->arch.pgd = NULL;
+}
+
+/*
+ * Clear a stage-2 PTE, lowering the various ref-counts. Also takes
+ * care of invalidating the TLBs.  Must be called while holding
+ * pgd_lock, otherwise another faulting VCPU may come in and mess
+ * things behind our back.
+ */
+static void stage2_clear_pte(struct kvm *kvm, phys_addr_t addr) {
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd;
+	pte_t *pte;
+	struct page *page;
+
+	kvm_debug("Clearing PTE&%08llx\n", addr);
+	pgd = kvm->arch.pgd + pgd_index(addr);
+	pud = pud_offset(pgd, addr);
+	BUG_ON(pud_none(*pud));
+
+	pmd = pmd_offset(pud, addr);
+	BUG_ON(pmd_none(*pmd));
+
+	pte = pte_offset_kernel(pmd, addr);
+	set_pte_ext(pte, __pte(0), 0);
+
+	page = virt_to_page(pte);
+	put_page(page);
+	if (page_count(page) != 1) {
+		__kvm_tlb_flush_vmid(kvm);
+		return;
+	}
+
+	/* Need to remove pte page */
+	pmd_clear(pmd);
+	__kvm_tlb_flush_vmid(kvm);
+	pte_free_kernel(NULL, (pte_t *)((unsigned long)pte & PAGE_MASK));
+
+	page = virt_to_page(pmd);
+	put_page(page);
+	if (page_count(page) != 1)
+		return;
+
+	/*
+	 * Need to remove pmd page. This is the worst case, and we end
+	 * up invalidating the TLB twice. No big deal.
+	 */
+	pud_clear(pud);
+	__kvm_tlb_flush_vmid(kvm);
+	pmd_free(NULL, (pmd_t *)((unsigned long)pmd & PAGE_MASK));
+
+	page = virt_to_page(pud);
+	put_page(page);
+}
+
+static void stage2_set_pte(struct kvm *kvm, struct kvm_mmu_memory_cache *cache,
+			   phys_addr_t addr, const pte_t *new_pte) {
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd;
+	pte_t *pte;
+
+	/* Create 2nd stage page table mapping - Level 1 */
+	pgd = kvm->arch.pgd + pgd_index(addr);
+	pud = pud_offset(pgd, addr);
+	if (pud_none(*pud)) {
+		if (!cache)
+			return; /* ignore calls from kvm_set_spte_hva */
+		pmd = mmu_memory_cache_alloc(cache);
+		pud_populate(NULL, pud, pmd);
+		pmd += pmd_index(addr);
+		get_page(virt_to_page(pud));
+	} else
+		pmd = pmd_offset(pud, addr);
+
+	/* Create 2nd stage page table mapping - Level 2 */
+	if (pmd_none(*pmd)) {
+		if (!cache)
+			return; /* ignore calls from kvm_set_spte_hva */
+		pte = mmu_memory_cache_alloc(cache);
+		clean_pte_table(pte);
+		pmd_populate_kernel(NULL, pmd, pte);
+		pte += pte_index(addr);
+		get_page(virt_to_page(pmd));
+	} else
+		pte = pte_offset_kernel(pmd, addr);
+
+	/* Create 2nd stage page table mapping - Level 3 */
+	BUG_ON(pte_none(pte));
+	set_pte_ext(pte, *new_pte, 0);
+	get_page(virt_to_page(pte));
+}
+
+/**
+ * kvm_phys_addr_ioremap - map a device range to guest IPA
+ *
+ * @kvm:	The KVM pointer
+ * @guest_ipa:	The IPA at which to insert the mapping
+ * @pa:		The physical address of the device
+ * @size:	The size of the mapping
+ */
+int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
+			  phys_addr_t pa, unsigned long size) {
+	phys_addr_t addr, end;
+	pgprot_t prot;
+	int ret = 0;
+	unsigned long pfn;
+	struct kvm_mmu_memory_cache cache = { 0, };
+
+	end = (guest_ipa + size + PAGE_SIZE - 1) & PAGE_MASK;
+	prot = __pgprot(get_mem_type_prot_pte(MT_DEVICE) | L_PTE_USER |
+			L_PTE2_READ | L_PTE2_WRITE);
+	pfn = __phys_to_pfn(pa);
+
+	for (addr = guest_ipa; addr < end; addr += PAGE_SIZE) {
+		pte_t pte = pfn_pte(pfn, prot);
+
+		ret = mmu_topup_memory_cache(&cache, 2, 2);
+		if (ret)
+			goto out;
+		spin_lock(&kvm->arch.pgd_lock);
+		stage2_set_pte(kvm, &cache, addr, &pte);
+		spin_unlock(&kvm->arch.pgd_lock);
+
+		pfn++;
+	}
+
+out:
+	mmu_free_memory_cache(&cache);
+	return ret;
+}
+
 int kvm_handle_guest_abort(struct kvm_vcpu *vcpu, struct kvm_run *run)  {
 	return -EINVAL;
 }
+
+static bool hva_to_gpa(struct kvm *kvm, unsigned long hva, gpa_t *gpa) 
+{
+	struct kvm_memslots *slots;
+	struct kvm_memory_slot *memslot;
+	bool found = false;
+
+	slots = kvm_memslots(kvm);
+
+	/* we only care about the pages that the guest sees */
+	kvm_for_each_memslot(memslot, slots) {
+		unsigned long start = memslot->userspace_addr;
+		unsigned long end;
+
+		end = start + (memslot->npages << PAGE_SHIFT);
+		if (hva >= start && hva < end) {
+			gpa_t gpa_offset = hva - start;
+			*gpa = (memslot->base_gfn << PAGE_SHIFT) + gpa_offset;
+			found = true;
+			/* no overlapping memslots allowed: break */
+			break;
+		}
+	}
+
+	return found;
+}
+
+int kvm_unmap_hva(struct kvm *kvm, unsigned long hva) {
+	bool found;
+	gpa_t gpa;
+
+	if (!kvm->arch.pgd)
+		return 0;
+
+	found = hva_to_gpa(kvm, hva, &gpa);
+	if (found) {
+		spin_lock(&kvm->arch.pgd_lock);
+		stage2_clear_pte(kvm, gpa);
+		spin_unlock(&kvm->arch.pgd_lock);
+	}
+	return 0;
+}
+
+int kvm_unmap_hva_range(struct kvm *kvm,
+			unsigned long start, unsigned long end) {
+	unsigned long addr;
+	int ret;
+
+	BUG_ON((start | end) & (~PAGE_MASK));
+
+	for (addr = start; addr < end; addr += PAGE_SIZE) {
+		ret = kvm_unmap_hva(kvm, addr);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+void kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte) {
+	gpa_t gpa;
+	bool found;
+
+	if (!kvm->arch.pgd)
+		return;
+
+	found = hva_to_gpa(kvm, hva, &gpa);
+	if (found) {
+		spin_lock(&kvm->arch.pgd_lock);
+		stage2_set_pte(kvm, NULL, gpa, &pte);
+		spin_unlock(&kvm->arch.pgd_lock);
+		__kvm_tlb_flush_vmid(kvm);
+	}
+}
+
+void kvm_mmu_free_memory_caches(struct kvm_vcpu *vcpu) {
+	mmu_free_memory_cache(&vcpu->arch.mmu_page_cache);
+}
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c index 76bf4f5..a153fd4 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -56,9 +56,11 @@ static unsigned int cachepolicy __initdata = CPOLICY_WRITEBACK;  static unsigned int ecc_mask __initdata = 0;  pgprot_t pgprot_user;  pgprot_t pgprot_kernel;
+pgprot_t pgprot_guest;
 
 EXPORT_SYMBOL(pgprot_user);
 EXPORT_SYMBOL(pgprot_kernel);
+EXPORT_SYMBOL(pgprot_guest);
 
 struct cachepolicy {
 	const char	policy[16];
@@ -514,6 +516,7 @@ static void __init build_mem_type_table(void)
 	pgprot_user   = __pgprot(L_PTE_PRESENT | L_PTE_YOUNG | user_pgprot);
 	pgprot_kernel = __pgprot(L_PTE_PRESENT | L_PTE_YOUNG |
 				 L_PTE_DIRTY | kern_pgprot);
+	pgprot_guest  = __pgprot(L_PTE_PRESENT | L_PTE_YOUNG);
 
 	mem_types[MT_LOW_VECTORS].prot_l1 |= ecc_mask;
 	mem_types[MT_HIGH_VECTORS].prot_l1 |= ecc_mask;

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