1 files changed, 793 insertions, 0 deletions

diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
new file mode 100644
index 000000000000..a9e2fd7245e1
--- /dev/null
+++ b/arch/riscv/kvm/mmu.c
@@ -0,0 +1,793 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *     Anup Patel <anup.patel@wdc.com>
+ */
+
+#include <linux/bitops.h>
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/hugetlb.h>
+#include <linux/module.h>
+#include <linux/uaccess.h>
+#include <linux/vmalloc.h>
+#include <linux/kvm_host.h>
+#include <linux/sched/signal.h>
+#include <asm/csr.h>
+#include <asm/page.h>
+#include <asm/pgtable.h>
+
+#ifdef CONFIG_64BIT
+static unsigned long gstage_mode __ro_after_init = (HGATP_MODE_SV39X4 << HGATP_MODE_SHIFT);
+static unsigned long gstage_pgd_levels __ro_after_init = 3;
+#define gstage_index_bits	9
+#else
+static unsigned long gstage_mode __ro_after_init = (HGATP_MODE_SV32X4 << HGATP_MODE_SHIFT);
+static unsigned long gstage_pgd_levels __ro_after_init = 2;
+#define gstage_index_bits	10
+#endif
+
+#define gstage_pgd_xbits	2
+#define gstage_pgd_size	(1UL << (HGATP_PAGE_SHIFT + gstage_pgd_xbits))
+#define gstage_gpa_bits	(HGATP_PAGE_SHIFT + \
+			 (gstage_pgd_levels * gstage_index_bits) + \
+			 gstage_pgd_xbits)
+#define gstage_gpa_size	((gpa_t)(1ULL << gstage_gpa_bits))
+
+#define gstage_pte_leaf(__ptep)	\
+	(pte_val(*(__ptep)) & (_PAGE_READ | _PAGE_WRITE | _PAGE_EXEC))
+
+static inline unsigned long gstage_pte_index(gpa_t addr, u32 level)
+{
+	unsigned long mask;
+	unsigned long shift = HGATP_PAGE_SHIFT + (gstage_index_bits * level);
+
+	if (level == (gstage_pgd_levels - 1))
+		mask = (PTRS_PER_PTE * (1UL << gstage_pgd_xbits)) - 1;
+	else
+		mask = PTRS_PER_PTE - 1;
+
+	return (addr >> shift) & mask;
+}
+
+static inline unsigned long gstage_pte_page_vaddr(pte_t pte)
+{
+	return (unsigned long)pfn_to_virt(__page_val_to_pfn(pte_val(pte)));
+}
+
+static int gstage_page_size_to_level(unsigned long page_size, u32 *out_level)
+{
+	u32 i;
+	unsigned long psz = 1UL << 12;
+
+	for (i = 0; i < gstage_pgd_levels; i++) {
+		if (page_size == (psz << (i * gstage_index_bits))) {
+			*out_level = i;
+			return 0;
+		}
+	}
+
+	return -EINVAL;
+}
+
+static int gstage_level_to_page_order(u32 level, unsigned long *out_pgorder)
+{
+	if (gstage_pgd_levels < level)
+		return -EINVAL;
+
+	*out_pgorder = 12 + (level * gstage_index_bits);
+	return 0;
+}
+
+static int gstage_level_to_page_size(u32 level, unsigned long *out_pgsize)
+{
+	int rc;
+	unsigned long page_order = PAGE_SHIFT;
+
+	rc = gstage_level_to_page_order(level, &page_order);
+	if (rc)
+		return rc;
+
+	*out_pgsize = BIT(page_order);
+	return 0;
+}
+
+static bool gstage_get_leaf_entry(struct kvm *kvm, gpa_t addr,
+				  pte_t **ptepp, u32 *ptep_level)
+{
+	pte_t *ptep;
+	u32 current_level = gstage_pgd_levels - 1;
+
+	*ptep_level = current_level;
+	ptep = (pte_t *)kvm->arch.pgd;
+	ptep = &ptep[gstage_pte_index(addr, current_level)];
+	while (ptep && pte_val(ptep_get(ptep))) {
+		if (gstage_pte_leaf(ptep)) {
+			*ptep_level = current_level;
+			*ptepp = ptep;
+			return true;
+		}
+
+		if (current_level) {
+			current_level--;
+			*ptep_level = current_level;
+			ptep = (pte_t *)gstage_pte_page_vaddr(ptep_get(ptep));
+			ptep = &ptep[gstage_pte_index(addr, current_level)];
+		} else {
+			ptep = NULL;
+		}
+	}
+
+	return false;
+}
+
+static void gstage_remote_tlb_flush(struct kvm *kvm, u32 level, gpa_t addr)
+{
+	unsigned long order = PAGE_SHIFT;
+
+	if (gstage_level_to_page_order(level, &order))
+		return;
+	addr &= ~(BIT(order) - 1);
+
+	kvm_riscv_hfence_gvma_vmid_gpa(kvm, -1UL, 0, addr, BIT(order), order);
+}
+
+static int gstage_set_pte(struct kvm *kvm, u32 level,
+			   struct kvm_mmu_memory_cache *pcache,
+			   gpa_t addr, const pte_t *new_pte)
+{
+	u32 current_level = gstage_pgd_levels - 1;
+	pte_t *next_ptep = (pte_t *)kvm->arch.pgd;
+	pte_t *ptep = &next_ptep[gstage_pte_index(addr, current_level)];
+
+	if (current_level < level)
+		return -EINVAL;
+
+	while (current_level != level) {
+		if (gstage_pte_leaf(ptep))
+			return -EEXIST;
+
+		if (!pte_val(ptep_get(ptep))) {
+			if (!pcache)
+				return -ENOMEM;
+			next_ptep = kvm_mmu_memory_cache_alloc(pcache);
+			if (!next_ptep)
+				return -ENOMEM;
+			set_pte(ptep, pfn_pte(PFN_DOWN(__pa(next_ptep)),
+					      __pgprot(_PAGE_TABLE)));
+		} else {
+			if (gstage_pte_leaf(ptep))
+				return -EEXIST;
+			next_ptep = (pte_t *)gstage_pte_page_vaddr(ptep_get(ptep));
+		}
+
+		current_level--;
+		ptep = &next_ptep[gstage_pte_index(addr, current_level)];
+	}
+
+	set_pte(ptep, *new_pte);
+	if (gstage_pte_leaf(ptep))
+		gstage_remote_tlb_flush(kvm, current_level, addr);
+
+	return 0;
+}
+
+static int gstage_map_page(struct kvm *kvm,
+			   struct kvm_mmu_memory_cache *pcache,
+			   gpa_t gpa, phys_addr_t hpa,
+			   unsigned long page_size,
+			   bool page_rdonly, bool page_exec)
+{
+	int ret;
+	u32 level = 0;
+	pte_t new_pte;
+	pgprot_t prot;
+
+	ret = gstage_page_size_to_level(page_size, &level);
+	if (ret)
+		return ret;
+
+	/*
+	 * A RISC-V implementation can choose to either:
+	 * 1) Update 'A' and 'D' PTE bits in hardware
+	 * 2) Generate page fault when 'A' and/or 'D' bits are not set
+	 *    PTE so that software can update these bits.
+	 *
+	 * We support both options mentioned above. To achieve this, we
+	 * always set 'A' and 'D' PTE bits at time of creating G-stage
+	 * mapping. To support KVM dirty page logging with both options
+	 * mentioned above, we will write-protect G-stage PTEs to track
+	 * dirty pages.
+	 */
+
+	if (page_exec) {
+		if (page_rdonly)
+			prot = PAGE_READ_EXEC;
+		else
+			prot = PAGE_WRITE_EXEC;
+	} else {
+		if (page_rdonly)
+			prot = PAGE_READ;
+		else
+			prot = PAGE_WRITE;
+	}
+	new_pte = pfn_pte(PFN_DOWN(hpa), prot);
+	new_pte = pte_mkdirty(new_pte);
+
+	return gstage_set_pte(kvm, level, pcache, gpa, &new_pte);
+}
+
+enum gstage_op {
+	GSTAGE_OP_NOP = 0,	/* Nothing */
+	GSTAGE_OP_CLEAR,	/* Clear/Unmap */
+	GSTAGE_OP_WP,		/* Write-protect */
+};
+
+static void gstage_op_pte(struct kvm *kvm, gpa_t addr,
+			  pte_t *ptep, u32 ptep_level, enum gstage_op op)
+{
+	int i, ret;
+	pte_t *next_ptep;
+	u32 next_ptep_level;
+	unsigned long next_page_size, page_size;
+
+	ret = gstage_level_to_page_size(ptep_level, &page_size);
+	if (ret)
+		return;
+
+	BUG_ON(addr & (page_size - 1));
+
+	if (!pte_val(ptep_get(ptep)))
+		return;
+
+	if (ptep_level && !gstage_pte_leaf(ptep)) {
+		next_ptep = (pte_t *)gstage_pte_page_vaddr(ptep_get(ptep));
+		next_ptep_level = ptep_level - 1;
+		ret = gstage_level_to_page_size(next_ptep_level,
+						&next_page_size);
+		if (ret)
+			return;
+
+		if (op == GSTAGE_OP_CLEAR)
+			set_pte(ptep, __pte(0));
+		for (i = 0; i < PTRS_PER_PTE; i++)
+			gstage_op_pte(kvm, addr + i * next_page_size,
+					&next_ptep[i], next_ptep_level, op);
+		if (op == GSTAGE_OP_CLEAR)
+			put_page(virt_to_page(next_ptep));
+	} else {
+		if (op == GSTAGE_OP_CLEAR)
+			set_pte(ptep, __pte(0));
+		else if (op == GSTAGE_OP_WP)
+			set_pte(ptep, __pte(pte_val(ptep_get(ptep)) & ~_PAGE_WRITE));
+		gstage_remote_tlb_flush(kvm, ptep_level, addr);
+	}
+}
+
+static void gstage_unmap_range(struct kvm *kvm, gpa_t start,
+			       gpa_t size, bool may_block)
+{
+	int ret;
+	pte_t *ptep;
+	u32 ptep_level;
+	bool found_leaf;
+	unsigned long page_size;
+	gpa_t addr = start, end = start + size;
+
+	while (addr < end) {
+		found_leaf = gstage_get_leaf_entry(kvm, addr,
+						   &ptep, &ptep_level);
+		ret = gstage_level_to_page_size(ptep_level, &page_size);
+		if (ret)
+			break;
+
+		if (!found_leaf)
+			goto next;
+
+		if (!(addr & (page_size - 1)) && ((end - addr) >= page_size))
+			gstage_op_pte(kvm, addr, ptep,
+				      ptep_level, GSTAGE_OP_CLEAR);
+
+next:
+		addr += page_size;
+
+		/*
+		 * If the range is too large, release the kvm->mmu_lock
+		 * to prevent starvation and lockup detector warnings.
+		 */
+		if (may_block && addr < end)
+			cond_resched_lock(&kvm->mmu_lock);
+	}
+}
+
+static void gstage_wp_range(struct kvm *kvm, gpa_t start, gpa_t end)
+{
+	int ret;
+	pte_t *ptep;
+	u32 ptep_level;
+	bool found_leaf;
+	gpa_t addr = start;
+	unsigned long page_size;
+
+	while (addr < end) {
+		found_leaf = gstage_get_leaf_entry(kvm, addr,
+						   &ptep, &ptep_level);
+		ret = gstage_level_to_page_size(ptep_level, &page_size);
+		if (ret)
+			break;
+
+		if (!found_leaf)
+			goto next;
+
+		if (!(addr & (page_size - 1)) && ((end - addr) >= page_size))
+			gstage_op_pte(kvm, addr, ptep,
+				      ptep_level, GSTAGE_OP_WP);
+
+next:
+		addr += page_size;
+	}
+}
+
+static void gstage_wp_memory_region(struct kvm *kvm, int slot)
+{
+	struct kvm_memslots *slots = kvm_memslots(kvm);
+	struct kvm_memory_slot *memslot = id_to_memslot(slots, slot);
+	phys_addr_t start = memslot->base_gfn << PAGE_SHIFT;
+	phys_addr_t end = (memslot->base_gfn + memslot->npages) << PAGE_SHIFT;
+
+	spin_lock(&kvm->mmu_lock);
+	gstage_wp_range(kvm, start, end);
+	spin_unlock(&kvm->mmu_lock);
+	kvm_flush_remote_tlbs(kvm);
+}
+
+int kvm_riscv_gstage_ioremap(struct kvm *kvm, gpa_t gpa,
+			     phys_addr_t hpa, unsigned long size,
+			     bool writable, bool in_atomic)
+{
+	pte_t pte;
+	int ret = 0;
+	unsigned long pfn;
+	phys_addr_t addr, end;
+	struct kvm_mmu_memory_cache pcache = {
+		.gfp_custom = (in_atomic) ? GFP_ATOMIC | __GFP_ACCOUNT : 0,
+		.gfp_zero = __GFP_ZERO,
+	};
+
+	end = (gpa + size + PAGE_SIZE - 1) & PAGE_MASK;
+	pfn = __phys_to_pfn(hpa);
+
+	for (addr = gpa; addr < end; addr += PAGE_SIZE) {
+		pte = pfn_pte(pfn, PAGE_KERNEL_IO);
+
+		if (!writable)
+			pte = pte_wrprotect(pte);
+
+		ret = kvm_mmu_topup_memory_cache(&pcache, gstage_pgd_levels);
+		if (ret)
+			goto out;
+
+		spin_lock(&kvm->mmu_lock);
+		ret = gstage_set_pte(kvm, 0, &pcache, addr, &pte);
+		spin_unlock(&kvm->mmu_lock);
+		if (ret)
+			goto out;
+
+		pfn++;
+	}
+
+out:
+	kvm_mmu_free_memory_cache(&pcache);
+	return ret;
+}
+
+void kvm_riscv_gstage_iounmap(struct kvm *kvm, gpa_t gpa, unsigned long size)
+{
+	spin_lock(&kvm->mmu_lock);
+	gstage_unmap_range(kvm, gpa, size, false);
+	spin_unlock(&kvm->mmu_lock);
+}
+
+void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
+					     struct kvm_memory_slot *slot,
+					     gfn_t gfn_offset,
+					     unsigned long mask)
+{
+	phys_addr_t base_gfn = slot->base_gfn + gfn_offset;
+	phys_addr_t start = (base_gfn +  __ffs(mask)) << PAGE_SHIFT;
+	phys_addr_t end = (base_gfn + __fls(mask) + 1) << PAGE_SHIFT;
+
+	gstage_wp_range(kvm, start, end);
+}
+
+void kvm_arch_sync_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot)
+{
+}
+
+void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free)
+{
+}
+
+void kvm_arch_memslots_updated(struct kvm *kvm, u64 gen)
+{
+}
+
+void kvm_arch_flush_shadow_all(struct kvm *kvm)
+{
+	kvm_riscv_gstage_free_pgd(kvm);
+}
+
+void kvm_arch_flush_shadow_memslot(struct kvm *kvm,
+				   struct kvm_memory_slot *slot)
+{
+	gpa_t gpa = slot->base_gfn << PAGE_SHIFT;
+	phys_addr_t size = slot->npages << PAGE_SHIFT;
+
+	spin_lock(&kvm->mmu_lock);
+	gstage_unmap_range(kvm, gpa, size, false);
+	spin_unlock(&kvm->mmu_lock);
+}
+
+void kvm_arch_commit_memory_region(struct kvm *kvm,
+				struct kvm_memory_slot *old,
+				const struct kvm_memory_slot *new,
+				enum kvm_mr_change change)
+{
+	/*
+	 * At this point memslot has been committed and there is an
+	 * allocated dirty_bitmap[], dirty pages will be tracked while
+	 * the memory slot is write protected.
+	 */
+	if (change != KVM_MR_DELETE && new->flags & KVM_MEM_LOG_DIRTY_PAGES)
+		gstage_wp_memory_region(kvm, new->id);
+}
+
+int kvm_arch_prepare_memory_region(struct kvm *kvm,
+				const struct kvm_memory_slot *old,
+				struct kvm_memory_slot *new,
+				enum kvm_mr_change change)
+{
+	hva_t hva, reg_end, size;
+	gpa_t base_gpa;
+	bool writable;
+	int ret = 0;
+
+	if (change != KVM_MR_CREATE && change != KVM_MR_MOVE &&
+			change != KVM_MR_FLAGS_ONLY)
+		return 0;
+
+	/*
+	 * Prevent userspace from creating a memory region outside of the GPA
+	 * space addressable by the KVM guest GPA space.
+	 */
+	if ((new->base_gfn + new->npages) >=
+	    (gstage_gpa_size >> PAGE_SHIFT))
+		return -EFAULT;
+
+	hva = new->userspace_addr;
+	size = new->npages << PAGE_SHIFT;
+	reg_end = hva + size;
+	base_gpa = new->base_gfn << PAGE_SHIFT;
+	writable = !(new->flags & KVM_MEM_READONLY);
+
+	mmap_read_lock(current->mm);
+
+	/*
+	 * A memory region could potentially cover multiple VMAs, and
+	 * any holes between them, so iterate over all of them to find
+	 * out if we can map any of them right now.
+	 *
+	 *     +--------------------------------------------+
+	 * +---------------+----------------+   +----------------+
+	 * |   : VMA 1     |      VMA 2     |   |    VMA 3  :    |
+	 * +---------------+----------------+   +----------------+
+	 *     |               memory region                |
+	 *     +--------------------------------------------+
+	 */
+	do {
+		struct vm_area_struct *vma = find_vma(current->mm, hva);
+		hva_t vm_start, vm_end;
+
+		if (!vma || vma->vm_start >= reg_end)
+			break;
+
+		/*
+		 * Mapping a read-only VMA is only allowed if the
+		 * memory region is configured as read-only.
+		 */
+		if (writable && !(vma->vm_flags & VM_WRITE)) {
+			ret = -EPERM;
+			break;
+		}
+
+		/* Take the intersection of this VMA with the memory region */
+		vm_start = max(hva, vma->vm_start);
+		vm_end = min(reg_end, vma->vm_end);
+
+		if (vma->vm_flags & VM_PFNMAP) {
+			gpa_t gpa = base_gpa + (vm_start - hva);
+			phys_addr_t pa;
+
+			pa = (phys_addr_t)vma->vm_pgoff << PAGE_SHIFT;
+			pa += vm_start - vma->vm_start;
+
+			/* IO region dirty page logging not allowed */
+			if (new->flags & KVM_MEM_LOG_DIRTY_PAGES) {
+				ret = -EINVAL;
+				goto out;
+			}
+
+			ret = kvm_riscv_gstage_ioremap(kvm, gpa, pa,
+						       vm_end - vm_start,
+						       writable, false);
+			if (ret)
+				break;
+		}
+		hva = vm_end;
+	} while (hva < reg_end);
+
+	if (change == KVM_MR_FLAGS_ONLY)
+		goto out;
+
+	if (ret)
+		kvm_riscv_gstage_iounmap(kvm, base_gpa, size);
+
+out:
+	mmap_read_unlock(current->mm);
+	return ret;
+}
+
+bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range)
+{
+	if (!kvm->arch.pgd)
+		return false;
+
+	gstage_unmap_range(kvm, range->start << PAGE_SHIFT,
+			   (range->end - range->start) << PAGE_SHIFT,
+			   range->may_block);
+	return false;
+}
+
+bool kvm_set_spte_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
+{
+	int ret;
+	kvm_pfn_t pfn = pte_pfn(range->arg.pte);
+
+	if (!kvm->arch.pgd)
+		return false;
+
+	WARN_ON(range->end - range->start != 1);
+
+	ret = gstage_map_page(kvm, NULL, range->start << PAGE_SHIFT,
+			      __pfn_to_phys(pfn), PAGE_SIZE, true, true);
+	if (ret) {
+		kvm_debug("Failed to map G-stage page (error %d)\n", ret);
+		return true;
+	}
+
+	return false;
+}
+
+bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
+{
+	pte_t *ptep;
+	u32 ptep_level = 0;
+	u64 size = (range->end - range->start) << PAGE_SHIFT;
+
+	if (!kvm->arch.pgd)
+		return false;
+
+	WARN_ON(size != PAGE_SIZE && size != PMD_SIZE && size != PUD_SIZE);
+
+	if (!gstage_get_leaf_entry(kvm, range->start << PAGE_SHIFT,
+				   &ptep, &ptep_level))
+		return false;
+
+	return ptep_test_and_clear_young(NULL, 0, ptep);
+}
+
+bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
+{
+	pte_t *ptep;
+	u32 ptep_level = 0;
+	u64 size = (range->end - range->start) << PAGE_SHIFT;
+
+	if (!kvm->arch.pgd)
+		return false;
+
+	WARN_ON(size != PAGE_SIZE && size != PMD_SIZE && size != PUD_SIZE);
+
+	if (!gstage_get_leaf_entry(kvm, range->start << PAGE_SHIFT,
+				   &ptep, &ptep_level))
+		return false;
+
+	return pte_young(ptep_get(ptep));
+}
+
+int kvm_riscv_gstage_map(struct kvm_vcpu *vcpu,
+			 struct kvm_memory_slot *memslot,
+			 gpa_t gpa, unsigned long hva, bool is_write)
+{
+	int ret;
+	kvm_pfn_t hfn;
+	bool writable;
+	short vma_pageshift;
+	gfn_t gfn = gpa >> PAGE_SHIFT;
+	struct vm_area_struct *vma;
+	struct kvm *kvm = vcpu->kvm;
+	struct kvm_mmu_memory_cache *pcache = &vcpu->arch.mmu_page_cache;
+	bool logging = (memslot->dirty_bitmap &&
+			!(memslot->flags & KVM_MEM_READONLY)) ? true : false;
+	unsigned long vma_pagesize, mmu_seq;
+
+	/* We need minimum second+third level pages */
+	ret = kvm_mmu_topup_memory_cache(pcache, gstage_pgd_levels);
+	if (ret) {
+		kvm_err("Failed to topup G-stage cache\n");
+		return ret;
+	}
+
+	mmap_read_lock(current->mm);
+
+	vma = vma_lookup(current->mm, hva);
+	if (unlikely(!vma)) {
+		kvm_err("Failed to find VMA for hva 0x%lx\n", hva);
+		mmap_read_unlock(current->mm);
+		return -EFAULT;
+	}
+
+	if (is_vm_hugetlb_page(vma))
+		vma_pageshift = huge_page_shift(hstate_vma(vma));
+	else
+		vma_pageshift = PAGE_SHIFT;
+	vma_pagesize = 1ULL << vma_pageshift;
+	if (logging || (vma->vm_flags & VM_PFNMAP))
+		vma_pagesize = PAGE_SIZE;
+
+	if (vma_pagesize == PMD_SIZE || vma_pagesize == PUD_SIZE)
+		gfn = (gpa & huge_page_mask(hstate_vma(vma))) >> PAGE_SHIFT;
+
+	/*
+	 * Read mmu_invalidate_seq so that KVM can detect if the results of
+	 * vma_lookup() or gfn_to_pfn_prot() become stale priort to acquiring
+	 * kvm->mmu_lock.
+	 *
+	 * Rely on mmap_read_unlock() for an implicit smp_rmb(), which pairs
+	 * with the smp_wmb() in kvm_mmu_invalidate_end().
+	 */
+	mmu_seq = kvm->mmu_invalidate_seq;
+	mmap_read_unlock(current->mm);
+
+	if (vma_pagesize != PUD_SIZE &&
+	    vma_pagesize != PMD_SIZE &&
+	    vma_pagesize != PAGE_SIZE) {
+		kvm_err("Invalid VMA page size 0x%lx\n", vma_pagesize);
+		return -EFAULT;
+	}
+
+	hfn = gfn_to_pfn_prot(kvm, gfn, is_write, &writable);
+	if (hfn == KVM_PFN_ERR_HWPOISON) {
+		send_sig_mceerr(BUS_MCEERR_AR, (void __user *)hva,
+				vma_pageshift, current);
+		return 0;
+	}
+	if (is_error_noslot_pfn(hfn))
+		return -EFAULT;
+
+	/*
+	 * If logging is active then we allow writable pages only
+	 * for write faults.
+	 */
+	if (logging && !is_write)
+		writable = false;
+
+	spin_lock(&kvm->mmu_lock);
+
+	if (mmu_invalidate_retry(kvm, mmu_seq))
+		goto out_unlock;
+
+	if (writable) {
+		kvm_set_pfn_dirty(hfn);
+		mark_page_dirty(kvm, gfn);
+		ret = gstage_map_page(kvm, pcache, gpa, hfn << PAGE_SHIFT,
+				      vma_pagesize, false, true);
+	} else {
+		ret = gstage_map_page(kvm, pcache, gpa, hfn << PAGE_SHIFT,
+				      vma_pagesize, true, true);
+	}
+
+	if (ret)
+		kvm_err("Failed to map in G-stage\n");
+
+out_unlock:
+	spin_unlock(&kvm->mmu_lock);
+	kvm_set_pfn_accessed(hfn);
+	kvm_release_pfn_clean(hfn);
+	return ret;
+}
+
+int kvm_riscv_gstage_alloc_pgd(struct kvm *kvm)
+{
+	struct page *pgd_page;
+
+	if (kvm->arch.pgd != NULL) {
+		kvm_err("kvm_arch already initialized?\n");
+		return -EINVAL;
+	}
+
+	pgd_page = alloc_pages(GFP_KERNEL | __GFP_ZERO,
+				get_order(gstage_pgd_size));
+	if (!pgd_page)
+		return -ENOMEM;
+	kvm->arch.pgd = page_to_virt(pgd_page);
+	kvm->arch.pgd_phys = page_to_phys(pgd_page);
+
+	return 0;
+}
+
+void kvm_riscv_gstage_free_pgd(struct kvm *kvm)
+{
+	void *pgd = NULL;
+
+	spin_lock(&kvm->mmu_lock);
+	if (kvm->arch.pgd) {
+		gstage_unmap_range(kvm, 0UL, gstage_gpa_size, false);
+		pgd = READ_ONCE(kvm->arch.pgd);
+		kvm->arch.pgd = NULL;
+		kvm->arch.pgd_phys = 0;
+	}
+	spin_unlock(&kvm->mmu_lock);
+
+	if (pgd)
+		free_pages((unsigned long)pgd, get_order(gstage_pgd_size));
+}
+
+void kvm_riscv_gstage_update_hgatp(struct kvm_vcpu *vcpu)
+{
+	unsigned long hgatp = gstage_mode;
+	struct kvm_arch *k = &vcpu->kvm->arch;
+
+	hgatp |= (READ_ONCE(k->vmid.vmid) << HGATP_VMID_SHIFT) & HGATP_VMID;
+	hgatp |= (k->pgd_phys >> PAGE_SHIFT) & HGATP_PPN;
+
+	csr_write(CSR_HGATP, hgatp);
+
+	if (!kvm_riscv_gstage_vmid_bits())
+		kvm_riscv_local_hfence_gvma_all();
+}
+
+void __init kvm_riscv_gstage_mode_detect(void)
+{
+#ifdef CONFIG_64BIT
+	/* Try Sv57x4 G-stage mode */
+	csr_write(CSR_HGATP, HGATP_MODE_SV57X4 << HGATP_MODE_SHIFT);
+	if ((csr_read(CSR_HGATP) >> HGATP_MODE_SHIFT) == HGATP_MODE_SV57X4) {
+		gstage_mode = (HGATP_MODE_SV57X4 << HGATP_MODE_SHIFT);
+		gstage_pgd_levels = 5;
+		goto skip_sv48x4_test;
+	}
+
+	/* Try Sv48x4 G-stage mode */
+	csr_write(CSR_HGATP, HGATP_MODE_SV48X4 << HGATP_MODE_SHIFT);
+	if ((csr_read(CSR_HGATP) >> HGATP_MODE_SHIFT) == HGATP_MODE_SV48X4) {
+		gstage_mode = (HGATP_MODE_SV48X4 << HGATP_MODE_SHIFT);
+		gstage_pgd_levels = 4;
+	}
+skip_sv48x4_test:
+
+	csr_write(CSR_HGATP, 0);
+	kvm_riscv_local_hfence_gvma_all();
+#endif
+}
+
+unsigned long __init kvm_riscv_gstage_mode(void)
+{
+	return gstage_mode >> HGATP_MODE_SHIFT;
+}
+
+int kvm_riscv_gstage_gpa_bits(void)
+{
+	return gstage_gpa_bits;
+}