[PATCH v14 10/17] RISC-V: KVM: Implement stage2 page table programming

[Anup Patel <anup.patel@wdc.com>]

This patch implements all required functions for programming
the stage2 page table for each Guest/VM.

At high-level, the flow of stage2 related functions is similar
from KVM ARM/ARM64 implementation but the stage2 page table
format is quite different for KVM RISC-V.

[jiangyifei: stage2 dirty log support]
Signed-off-by: Yifei Jiang <jiangyifei@huawei.com>
Signed-off-by: Anup Patel <anup.patel@wdc.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/riscv/include/asm/kvm_host.h     |  12 +
 arch/riscv/include/asm/pgtable-bits.h |   1 +
 arch/riscv/kvm/Kconfig                |   1 +
 arch/riscv/kvm/main.c                 |  19 +
 arch/riscv/kvm/mmu.c                  | 647 +++++++++++++++++++++++++-
 arch/riscv/kvm/vm.c                   |   6 -
 6 files changed, 670 insertions(+), 16 deletions(-)

diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
index ca4eb4ce1335..5d70c8cf3733 100644
--- a/arch/riscv/include/asm/kvm_host.h
+++ b/arch/riscv/include/asm/kvm_host.h
@@ -76,6 +76,13 @@ struct kvm_mmio_decode {
 	int return_handled;
 };
 
+#define KVM_MMU_PAGE_CACHE_NR_OBJS	32
+
+struct kvm_mmu_page_cache {
+	int nobjs;
+	void *objects[KVM_MMU_PAGE_CACHE_NR_OBJS];
+};
+
 struct kvm_cpu_trap {
 	unsigned long sepc;
 	unsigned long scause;
@@ -177,6 +184,9 @@ struct kvm_vcpu_arch {
 	/* MMIO instruction details */
 	struct kvm_mmio_decode mmio_decode;
 
+	/* Cache pages needed to program page tables with spinlock held */
+	struct kvm_mmu_page_cache mmu_page_cache;
+
 	/* VCPU power-off state */
 	bool power_off;
 
@@ -205,6 +215,8 @@ void kvm_riscv_stage2_flush_cache(struct kvm_vcpu *vcpu);
 int kvm_riscv_stage2_alloc_pgd(struct kvm *kvm);
 void kvm_riscv_stage2_free_pgd(struct kvm *kvm);
 void kvm_riscv_stage2_update_hgatp(struct kvm_vcpu *vcpu);
+void kvm_riscv_stage2_mode_detect(void);
+unsigned long kvm_riscv_stage2_mode(void);
 
 void kvm_riscv_stage2_vmid_detect(void);
 unsigned long kvm_riscv_stage2_vmid_bits(void);
diff --git a/arch/riscv/include/asm/pgtable-bits.h b/arch/riscv/include/asm/pgtable-bits.h
index bbaeb5d35842..be49d62fcc2b 100644
--- a/arch/riscv/include/asm/pgtable-bits.h
+++ b/arch/riscv/include/asm/pgtable-bits.h
@@ -26,6 +26,7 @@
 
 #define _PAGE_SPECIAL   _PAGE_SOFT
 #define _PAGE_TABLE     _PAGE_PRESENT
+#define _PAGE_LEAF      (_PAGE_READ | _PAGE_WRITE | _PAGE_EXEC)
 
 /*
  * _PAGE_PROT_NONE is set on not-present pages (and ignored by the hardware) to
diff --git a/arch/riscv/kvm/Kconfig b/arch/riscv/kvm/Kconfig
index b42979f84042..633063edaee8 100644
--- a/arch/riscv/kvm/Kconfig
+++ b/arch/riscv/kvm/Kconfig
@@ -23,6 +23,7 @@ config KVM
 	select PREEMPT_NOTIFIERS
 	select ANON_INODES
 	select KVM_MMIO
+	select KVM_GENERIC_DIRTYLOG_READ_PROTECT
 	select HAVE_KVM_VCPU_ASYNC_IOCTL
 	select HAVE_KVM_EVENTFD
 	select SRCU
diff --git a/arch/riscv/kvm/main.c b/arch/riscv/kvm/main.c
index 49a4941e3838..421ecf4e6360 100644
--- a/arch/riscv/kvm/main.c
+++ b/arch/riscv/kvm/main.c
@@ -64,6 +64,8 @@ void kvm_arch_hardware_disable(void)
 
 int kvm_arch_init(void *opaque)
 {
+	const char *str;
+
 	if (!riscv_isa_extension_available(NULL, h)) {
 		kvm_info("hypervisor extension not available\n");
 		return -ENODEV;
@@ -79,10 +81,27 @@ int kvm_arch_init(void *opaque)
 		return -ENODEV;
 	}
 
+	kvm_riscv_stage2_mode_detect();
+
 	kvm_riscv_stage2_vmid_detect();
 
 	kvm_info("hypervisor extension available\n");
 
+	switch (kvm_riscv_stage2_mode()) {
+	case HGATP_MODE_SV32X4:
+		str = "Sv32x4";
+		break;
+	case HGATP_MODE_SV39X4:
+		str = "Sv39x4";
+		break;
+	case HGATP_MODE_SV48X4:
+		str = "Sv48x4";
+		break;
+	default:
+		return -ENODEV;
+	}
+	kvm_info("using %s G-stage page table format\n", str);
+
 	kvm_info("VMID %ld bits available\n", kvm_riscv_stage2_vmid_bits());
 
 	return 0;
diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
index 8fb356e68cc5..35b9aabe6c57 100644
--- a/arch/riscv/kvm/mmu.c
+++ b/arch/riscv/kvm/mmu.c
@@ -17,11 +17,415 @@
 #include <linux/sched/signal.h>
 #include <asm/page.h>
 #include <asm/pgtable.h>
+#include <asm/sbi.h>
+
+#ifdef CONFIG_64BIT
+static unsigned long stage2_mode = (HGATP_MODE_SV39X4 << HGATP_MODE_SHIFT);
+static unsigned long stage2_pgd_levels = 3;
+#define stage2_index_bits	9
+#else
+static unsigned long stage2_mode = (HGATP_MODE_SV32X4 << HGATP_MODE_SHIFT);
+static unsigned long stage2_pgd_levels = 2;
+#define stage2_index_bits	10
+#endif
+
+#define stage2_pgd_xbits	2
+#define stage2_pgd_size	(1UL << (HGATP_PAGE_SHIFT + stage2_pgd_xbits))
+#define stage2_gpa_bits	(HGATP_PAGE_SHIFT + \
+			 (stage2_pgd_levels * stage2_index_bits) + \
+			 stage2_pgd_xbits)
+#define stage2_gpa_size	((gpa_t)(1ULL << stage2_gpa_bits))
+
+static inline unsigned long stage2_pte_index(gpa_t addr, u32 level)
+{
+	unsigned long mask;
+	unsigned long shift = HGATP_PAGE_SHIFT + (stage2_index_bits * level);
+
+	if (level == (stage2_pgd_levels - 1))
+		mask = (PTRS_PER_PTE * (1UL << stage2_pgd_xbits)) - 1;
+	else
+		mask = PTRS_PER_PTE - 1;
+
+	return (addr >> shift) & mask;
+}
+
+static inline unsigned long stage2_pte_page_vaddr(pte_t pte)
+{
+	return (unsigned long)pfn_to_virt(pte_val(pte) >> _PAGE_PFN_SHIFT);
+}
+
+static int stage2_page_size_to_level(unsigned long page_size, u32 *out_level)
+{
+	u32 i;
+	unsigned long psz = 1UL << 12;
+
+	for (i = 0; i < stage2_pgd_levels; i++) {
+		if (page_size == (psz << (i * stage2_index_bits))) {
+			*out_level = i;
+			return 0;
+		}
+	}
+
+	return -EINVAL;
+}
+
+static int stage2_level_to_page_size(u32 level, unsigned long *out_pgsize)
+{
+	if (stage2_pgd_levels < level)
+		return -EINVAL;
+
+	*out_pgsize = 1UL << (12 + (level * stage2_index_bits));
+
+	return 0;
+}
+
+static int stage2_cache_topup(struct kvm_mmu_page_cache *pcache,
+			      int min, int max)
+{
+	void *page;
+
+	BUG_ON(max > KVM_MMU_PAGE_CACHE_NR_OBJS);
+	if (pcache->nobjs >= min)
+		return 0;
+	while (pcache->nobjs < max) {
+		page = (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
+		if (!page)
+			return -ENOMEM;
+		pcache->objects[pcache->nobjs++] = page;
+	}
+
+	return 0;
+}
+
+static void stage2_cache_flush(struct kvm_mmu_page_cache *pcache)
+{
+	while (pcache && pcache->nobjs)
+		free_page((unsigned long)pcache->objects[--pcache->nobjs]);
+}
+
+static void *stage2_cache_alloc(struct kvm_mmu_page_cache *pcache)
+{
+	void *p;
+
+	if (!pcache)
+		return NULL;
+
+	BUG_ON(!pcache->nobjs);
+	p = pcache->objects[--pcache->nobjs];
+
+	return p;
+}
+
+static bool stage2_get_leaf_entry(struct kvm *kvm, gpa_t addr,
+				  pte_t **ptepp, u32 *ptep_level)
+{
+	pte_t *ptep;
+	u32 current_level = stage2_pgd_levels - 1;
+
+	*ptep_level = current_level;
+	ptep = (pte_t *)kvm->arch.pgd;
+	ptep = &ptep[stage2_pte_index(addr, current_level)];
+	while (ptep && pte_val(*ptep)) {
+		if (pte_val(*ptep) & _PAGE_LEAF) {
+			*ptep_level = current_level;
+			*ptepp = ptep;
+			return true;
+		}
+
+		if (current_level) {
+			current_level--;
+			*ptep_level = current_level;
+			ptep = (pte_t *)stage2_pte_page_vaddr(*ptep);
+			ptep = &ptep[stage2_pte_index(addr, current_level)];
+		} else {
+			ptep = NULL;
+		}
+	}
+
+	return false;
+}
+
+static void stage2_remote_tlb_flush(struct kvm *kvm, u32 level, gpa_t addr)
+{
+	struct cpumask hmask;
+	unsigned long size = PAGE_SIZE;
+	struct kvm_vmid *vmid = &kvm->arch.vmid;
+
+	if (stage2_level_to_page_size(level, &size))
+		return;
+	addr &= ~(size - 1);
+
+	/*
+	 * TODO: Instead of cpu_online_mask, we should only target CPUs
+	 * where the Guest/VM is running.
+	 */
+	preempt_disable();
+	riscv_cpuid_to_hartid_mask(cpu_online_mask, &hmask);
+	sbi_remote_hfence_gvma_vmid(cpumask_bits(&hmask), addr, size,
+				    READ_ONCE(vmid->vmid));
+	preempt_enable();
+}
+
+static int stage2_set_pte(struct kvm *kvm, u32 level,
+			   struct kvm_mmu_page_cache *pcache,
+			   gpa_t addr, const pte_t *new_pte)
+{
+	u32 current_level = stage2_pgd_levels - 1;
+	pte_t *next_ptep = (pte_t *)kvm->arch.pgd;
+	pte_t *ptep = &next_ptep[stage2_pte_index(addr, current_level)];
+
+	if (current_level < level)
+		return -EINVAL;
+
+	while (current_level != level) {
+		if (pte_val(*ptep) & _PAGE_LEAF)
+			return -EEXIST;
+
+		if (!pte_val(*ptep)) {
+			next_ptep = stage2_cache_alloc(pcache);
+			if (!next_ptep)
+				return -ENOMEM;
+			*ptep = pfn_pte(PFN_DOWN(__pa(next_ptep)),
+					__pgprot(_PAGE_TABLE));
+		} else {
+			if (pte_val(*ptep) & _PAGE_LEAF)
+				return -EEXIST;
+			next_ptep = (pte_t *)stage2_pte_page_vaddr(*ptep);
+		}
+
+		current_level--;
+		ptep = &next_ptep[stage2_pte_index(addr, current_level)];
+	}
+
+	*ptep = *new_pte;
+	if (pte_val(*ptep) & _PAGE_LEAF)
+		stage2_remote_tlb_flush(kvm, current_level, addr);
+
+	return 0;
+}
+
+static int stage2_map_page(struct kvm *kvm,
+			   struct kvm_mmu_page_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 = stage2_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 stage2
+	 * mapping. To support KVM dirty page logging with both options
+	 * mentioned above, we will write-protect stage2 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 stage2_set_pte(kvm, level, pcache, gpa, &new_pte);
+}
+
+enum stage2_op {
+	STAGE2_OP_NOP = 0,	/* Nothing */
+	STAGE2_OP_CLEAR,	/* Clear/Unmap */
+	STAGE2_OP_WP,		/* Write-protect */
+};
+
+static void stage2_op_pte(struct kvm *kvm, gpa_t addr,
+			  pte_t *ptep, u32 ptep_level, enum stage2_op op)
+{
+	int i, ret;
+	pte_t *next_ptep;
+	u32 next_ptep_level;
+	unsigned long next_page_size, page_size;
+
+	ret = stage2_level_to_page_size(ptep_level, &page_size);
+	if (ret)
+		return;
+
+	BUG_ON(addr & (page_size - 1));
+
+	if (!pte_val(*ptep))
+		return;
+
+	if (ptep_level && !(pte_val(*ptep) & _PAGE_LEAF)) {
+		next_ptep = (pte_t *)stage2_pte_page_vaddr(*ptep);
+		next_ptep_level = ptep_level - 1;
+		ret = stage2_level_to_page_size(next_ptep_level,
+						&next_page_size);
+		if (ret)
+			return;
+
+		if (op == STAGE2_OP_CLEAR)
+			set_pte(ptep, __pte(0));
+		for (i = 0; i < PTRS_PER_PTE; i++)
+			stage2_op_pte(kvm, addr + i * next_page_size,
+					&next_ptep[i], next_ptep_level, op);
+		if (op == STAGE2_OP_CLEAR)
+			put_page(virt_to_page(next_ptep));
+	} else {
+		if (op == STAGE2_OP_CLEAR)
+			set_pte(ptep, __pte(0));
+		else if (op == STAGE2_OP_WP)
+			set_pte(ptep, __pte(pte_val(*ptep) & ~_PAGE_WRITE));
+		stage2_remote_tlb_flush(kvm, ptep_level, addr);
+	}
+}
+
+static void stage2_unmap_range(struct kvm *kvm, gpa_t start, gpa_t size)
+{
+	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 = stage2_get_leaf_entry(kvm, addr,
+						   &ptep, &ptep_level);
+		ret = stage2_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))
+			stage2_op_pte(kvm, addr, ptep,
+				      ptep_level, STAGE2_OP_CLEAR);
+
+next:
+		addr += page_size;
+	}
+}
+
+static void stage2_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 = stage2_get_leaf_entry(kvm, addr,
+						   &ptep, &ptep_level);
+		ret = stage2_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))
+			stage2_op_pte(kvm, addr, ptep,
+				      ptep_level, STAGE2_OP_WP);
+
+next:
+		addr += page_size;
+	}
+}
+
+void stage2_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);
+	stage2_wp_range(kvm, start, end);
+	spin_unlock(&kvm->mmu_lock);
+	kvm_flush_remote_tlbs(kvm);
+}
+
+int stage2_ioremap(struct kvm *kvm, gpa_t gpa, phys_addr_t hpa,
+		   unsigned long size, bool writable)
+{
+	pte_t pte;
+	int ret = 0;
+	unsigned long pfn;
+	phys_addr_t addr, end;
+	struct kvm_mmu_page_cache pcache = { 0, };
+
+	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);
+
+		if (!writable)
+			pte = pte_wrprotect(pte);
+
+		ret = stage2_cache_topup(&pcache,
+					 stage2_pgd_levels,
+					 KVM_MMU_PAGE_CACHE_NR_OBJS);
+		if (ret)
+			goto out;
+
+		spin_lock(&kvm->mmu_lock);
+		ret = stage2_set_pte(kvm, 0, &pcache, addr, &pte);
+		spin_unlock(&kvm->mmu_lock);
+		if (ret)
+			goto out;
+
+		pfn++;
+	}
+
+out:
+	stage2_cache_flush(&pcache);
+	return ret;
+
+}
+
+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;
+
+	stage2_wp_range(kvm, start, end);
+}
 
 void kvm_arch_sync_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot)
 {
 }
 
+void kvm_arch_flush_remote_tlbs_memslot(struct kvm *kvm,
+					struct kvm_memory_slot *memslot)
+{
+	kvm_flush_remote_tlbs(kvm);
+}
+
 void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free)
 {
 }
@@ -38,7 +442,7 @@ void kvm_arch_memslots_updated(struct kvm *kvm, u64 gen)
 
 void kvm_arch_flush_shadow_all(struct kvm *kvm)
 {
-	/* TODO: */
+	kvm_riscv_stage2_free_pgd(kvm);
 }
 
 void kvm_arch_flush_shadow_memslot(struct kvm *kvm,
@@ -52,7 +456,13 @@ void kvm_arch_commit_memory_region(struct kvm *kvm,
 				const struct kvm_memory_slot *new,
 				enum kvm_mr_change change)
 {
-	/* TODO: */
+	/*
+	 * 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 && mem->flags & KVM_MEM_LOG_DIRTY_PAGES)
+		stage2_wp_memory_region(kvm, mem->slot);
 }
 
 int kvm_arch_prepare_memory_region(struct kvm *kvm,
@@ -60,35 +470,252 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
 				const struct kvm_userspace_memory_region *mem,
 				enum kvm_mr_change change)
 {
-	/* TODO: */
-	return 0;
+	hva_t hva = mem->userspace_addr;
+	hva_t reg_end = hva + mem->memory_size;
+	bool writable = !(mem->flags & KVM_MEM_READONLY);
+	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 ((memslot->base_gfn + memslot->npages) >=
+	    (stage2_gpa_size >> PAGE_SHIFT))
+		return -EFAULT;
+
+	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 = mem->guest_phys_addr +
+				    (vm_start - mem->userspace_addr);
+			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 (memslot->flags & KVM_MEM_LOG_DIRTY_PAGES) {
+				ret = -EINVAL;
+				goto out;
+			}
+
+			ret = stage2_ioremap(kvm, gpa, pa,
+					     vm_end - vm_start, writable);
+			if (ret)
+				break;
+		}
+		hva = vm_end;
+	} while (hva < reg_end);
+
+	if (change == KVM_MR_FLAGS_ONLY)
+		goto out;
+
+	spin_lock(&kvm->mmu_lock);
+	if (ret)
+		stage2_unmap_range(kvm, mem->guest_phys_addr,
+				   mem->memory_size);
+	spin_unlock(&kvm->mmu_lock);
+
+out:
+	mmap_read_unlock(current->mm);
+	return ret;
 }
 
 int kvm_riscv_stage2_map(struct kvm_vcpu *vcpu,
 			 struct kvm_memory_slot *memslot,
 			 gpa_t gpa, unsigned long hva, bool is_write)
 {
-	/* TODO: */
-	return 0;
+	int ret;
+	kvm_pfn_t hfn;
+	bool writeable;
+	short vma_pageshift;
+	gfn_t gfn = gpa >> PAGE_SHIFT;
+	struct vm_area_struct *vma;
+	struct kvm *kvm = vcpu->kvm;
+	struct kvm_mmu_page_cache *pcache = &vcpu->arch.mmu_page_cache;
+	bool logging = (memslot->dirty_bitmap &&
+			!(memslot->flags & KVM_MEM_READONLY)) ? true : false;
+	unsigned long vma_pagesize;
+
+	mmap_read_lock(current->mm);
+
+	vma = find_vma_intersection(current->mm, hva, hva + 1);
+	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 == PGDIR_SIZE)
+		gfn = (gpa & huge_page_mask(hstate_vma(vma))) >> PAGE_SHIFT;
+
+	mmap_read_unlock(current->mm);
+
+	if (vma_pagesize != PGDIR_SIZE &&
+	    vma_pagesize != PMD_SIZE &&
+	    vma_pagesize != PAGE_SIZE) {
+		kvm_err("Invalid VMA page size 0x%lx\n", vma_pagesize);
+		return -EFAULT;
+	}
+
+	/* We need minimum second+third level pages */
+	ret = stage2_cache_topup(pcache, stage2_pgd_levels,
+				 KVM_MMU_PAGE_CACHE_NR_OBJS);
+	if (ret) {
+		kvm_err("Failed to topup stage2 cache\n");
+		return ret;
+	}
+
+	hfn = gfn_to_pfn_prot(kvm, gfn, is_write, &writeable);
+	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)
+		writeable = false;
+
+	spin_lock(&kvm->mmu_lock);
+
+	if (writeable) {
+		kvm_set_pfn_dirty(hfn);
+		mark_page_dirty(kvm, gfn);
+		ret = stage2_map_page(kvm, pcache, gpa, hfn << PAGE_SHIFT,
+				      vma_pagesize, false, true);
+	} else {
+		ret = stage2_map_page(kvm, pcache, gpa, hfn << PAGE_SHIFT,
+				      vma_pagesize, true, true);
+	}
+
+	if (ret)
+		kvm_err("Failed to map in stage2\n");
+
+	spin_unlock(&kvm->mmu_lock);
+	kvm_set_pfn_accessed(hfn);
+	kvm_release_pfn_clean(hfn);
+	return ret;
 }
 
 void kvm_riscv_stage2_flush_cache(struct kvm_vcpu *vcpu)
 {
-	/* TODO: */
+	stage2_cache_flush(&vcpu->arch.mmu_page_cache);
 }
 
 int kvm_riscv_stage2_alloc_pgd(struct kvm *kvm)
 {
-	/* TODO: */
+	if (kvm->arch.pgd != NULL) {
+		kvm_err("kvm_arch already initialized?\n");
+		return -EINVAL;
+	}
+
+	kvm->arch.pgd = alloc_pages_exact(stage2_pgd_size,
+					  GFP_KERNEL | __GFP_ZERO);
+	if (!kvm->arch.pgd)
+		return -ENOMEM;
+	kvm->arch.pgd_phys = virt_to_phys(kvm->arch.pgd);
+
 	return 0;
 }
 
 void kvm_riscv_stage2_free_pgd(struct kvm *kvm)
 {
-	/* TODO: */
+	void *pgd = NULL;
+
+	spin_lock(&kvm->mmu_lock);
+	if (kvm->arch.pgd) {
+		stage2_unmap_range(kvm, 0UL, stage2_gpa_size);
+		pgd = READ_ONCE(kvm->arch.pgd);
+		kvm->arch.pgd = NULL;
+		kvm->arch.pgd_phys = 0;
+	}
+	spin_unlock(&kvm->mmu_lock);
+
+	if (pgd)
+		free_pages_exact(pgd, stage2_pgd_size);
 }
 
 void kvm_riscv_stage2_update_hgatp(struct kvm_vcpu *vcpu)
 {
-	/* TODO: */
+	unsigned long hgatp = stage2_mode;
+	struct kvm_arch *k = &vcpu->kvm->arch;
+
+	hgatp |= (READ_ONCE(k->vmid.vmid) << HGATP_VMID_SHIFT) &
+		 HGATP_VMID_MASK;
+	hgatp |= (k->pgd_phys >> PAGE_SHIFT) & HGATP_PPN;
+
+	csr_write(CSR_HGATP, hgatp);
+
+	if (!kvm_riscv_stage2_vmid_bits())
+		__kvm_riscv_hfence_gvma_all();
+}
+
+void kvm_riscv_stage2_mode_detect(void)
+{
+#ifdef CONFIG_64BIT
+	/* Try Sv48x4 stage2 mode */
+	csr_write(CSR_HGATP, HGATP_MODE_SV48X4 << HGATP_MODE_SHIFT);
+	if ((csr_read(CSR_HGATP) >> HGATP_MODE_SHIFT) == HGATP_MODE_SV48X4) {
+		stage2_mode = (HGATP_MODE_SV48X4 << HGATP_MODE_SHIFT);
+		stage2_pgd_levels = 4;
+	}
+	csr_write(CSR_HGATP, 0);
+
+	__kvm_riscv_hfence_gvma_all();
+#endif
+}
+
+unsigned long kvm_riscv_stage2_mode(void)
+{
+	return stage2_mode >> HGATP_MODE_SHIFT;
 }
diff --git a/arch/riscv/kvm/vm.c b/arch/riscv/kvm/vm.c
index 282d67617229..6cde69a82252 100644
--- a/arch/riscv/kvm/vm.c
+++ b/arch/riscv/kvm/vm.c
@@ -12,12 +12,6 @@
 #include <linux/uaccess.h>
 #include <linux/kvm_host.h>
 
-int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log)
-{
-	/* TODO: To be added later. */
-	return -EOPNOTSUPP;
-}
-
 int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 {
 	int r;
-- 
2.25.1