1 files changed, 369 insertions, 38 deletions

diff --git a/arch/arm64/kvm/hyp/nvhe/mm.c b/arch/arm64/kvm/hyp/nvhe/mm.c
index a8efdf0f9003..ae8391baebc3 100644
--- a/arch/arm64/kvm/hyp/nvhe/mm.c
+++ b/arch/arm64/kvm/hyp/nvhe/mm.c
@@ -8,23 +8,32 @@
 #include <asm/kvm_hyp.h>
 #include <asm/kvm_mmu.h>
 #include <asm/kvm_pgtable.h>
+#include <asm/kvm_pkvm.h>
 #include <asm/spectre.h>
 
 #include <nvhe/early_alloc.h>
 #include <nvhe/gfp.h>
 #include <nvhe/memory.h>
+#include <nvhe/mem_protect.h>
 #include <nvhe/mm.h>
 #include <nvhe/spinlock.h>
 
 struct kvm_pgtable pkvm_pgtable;
 hyp_spinlock_t pkvm_pgd_lock;
-u64 __io_map_base;
 
 struct memblock_region hyp_memory[HYP_MEMBLOCK_REGIONS];
 unsigned int hyp_memblock_nr;
 
-int __pkvm_create_mappings(unsigned long start, unsigned long size,
-			  unsigned long phys, enum kvm_pgtable_prot prot)
+static u64 __io_map_base;
+
+struct hyp_fixmap_slot {
+	u64 addr;
+	kvm_pte_t *ptep;
+};
+static DEFINE_PER_CPU(struct hyp_fixmap_slot, fixmap_slots);
+
+static int __pkvm_create_mappings(unsigned long start, unsigned long size,
+				  unsigned long phys, enum kvm_pgtable_prot prot)
 {
 	int err;
 
@@ -35,45 +44,81 @@ int __pkvm_create_mappings(unsigned long start, unsigned long size,
 	return err;
 }
 
-unsigned long __pkvm_create_private_mapping(phys_addr_t phys, size_t size,
-					    enum kvm_pgtable_prot prot)
+static int __pkvm_alloc_private_va_range(unsigned long start, size_t size)
 {
-	unsigned long addr;
-	int err;
+	unsigned long cur;
 
-	hyp_spin_lock(&pkvm_pgd_lock);
+	hyp_assert_lock_held(&pkvm_pgd_lock);
 
-	size = PAGE_ALIGN(size + offset_in_page(phys));
-	addr = __io_map_base;
-	__io_map_base += size;
+	if (!start || start < __io_map_base)
+		return -EINVAL;
+
+	/* The allocated size is always a multiple of PAGE_SIZE */
+	cur = start + PAGE_ALIGN(size);
 
 	/* Are we overflowing on the vmemmap ? */
-	if (__io_map_base > __hyp_vmemmap) {
-		__io_map_base -= size;
-		addr = (unsigned long)ERR_PTR(-ENOMEM);
-		goto out;
-	}
+	if (cur > __hyp_vmemmap)
+		return -ENOMEM;
 
-	err = kvm_pgtable_hyp_map(&pkvm_pgtable, addr, size, phys, prot);
-	if (err) {
-		addr = (unsigned long)ERR_PTR(err);
-		goto out;
-	}
+	__io_map_base = cur;
+
+	return 0;
+}
 
-	addr = addr + offset_in_page(phys);
-out:
+/**
+ * pkvm_alloc_private_va_range - Allocates a private VA range.
+ * @size:	The size of the VA range to reserve.
+ * @haddr:	The hypervisor virtual start address of the allocation.
+ *
+ * The private virtual address (VA) range is allocated above __io_map_base
+ * and aligned based on the order of @size.
+ *
+ * Return: 0 on success or negative error code on failure.
+ */
+int pkvm_alloc_private_va_range(size_t size, unsigned long *haddr)
+{
+	unsigned long addr;
+	int ret;
+
+	hyp_spin_lock(&pkvm_pgd_lock);
+	addr = __io_map_base;
+	ret = __pkvm_alloc_private_va_range(addr, size);
 	hyp_spin_unlock(&pkvm_pgd_lock);
 
-	return addr;
+	*haddr = addr;
+
+	return ret;
 }
 
-int pkvm_create_mappings(void *from, void *to, enum kvm_pgtable_prot prot)
+int __pkvm_create_private_mapping(phys_addr_t phys, size_t size,
+				  enum kvm_pgtable_prot prot,
+				  unsigned long *haddr)
+{
+	unsigned long addr;
+	int err;
+
+	size = PAGE_ALIGN(size + offset_in_page(phys));
+	err = pkvm_alloc_private_va_range(size, &addr);
+	if (err)
+		return err;
+
+	err = __pkvm_create_mappings(addr, size, phys, prot);
+	if (err)
+		return err;
+
+	*haddr = addr + offset_in_page(phys);
+	return err;
+}
+
+int pkvm_create_mappings_locked(void *from, void *to, enum kvm_pgtable_prot prot)
 {
 	unsigned long start = (unsigned long)from;
 	unsigned long end = (unsigned long)to;
 	unsigned long virt_addr;
 	phys_addr_t phys;
 
+	hyp_assert_lock_held(&pkvm_pgd_lock);
+
 	start = start & PAGE_MASK;
 	end = PAGE_ALIGN(end);
 
@@ -81,7 +126,8 @@ int pkvm_create_mappings(void *from, void *to, enum kvm_pgtable_prot prot)
 		int err;
 
 		phys = hyp_virt_to_phys((void *)virt_addr);
-		err = __pkvm_create_mappings(virt_addr, PAGE_SIZE, phys, prot);
+		err = kvm_pgtable_hyp_map(&pkvm_pgtable, virt_addr, PAGE_SIZE,
+					  phys, prot);
 		if (err)
 			return err;
 	}
@@ -89,13 +135,47 @@ int pkvm_create_mappings(void *from, void *to, enum kvm_pgtable_prot prot)
 	return 0;
 }
 
-int hyp_back_vmemmap(phys_addr_t phys, unsigned long size, phys_addr_t back)
+int pkvm_create_mappings(void *from, void *to, enum kvm_pgtable_prot prot)
 {
-	unsigned long start, end;
+	int ret;
 
-	hyp_vmemmap_range(phys, size, &start, &end);
+	hyp_spin_lock(&pkvm_pgd_lock);
+	ret = pkvm_create_mappings_locked(from, to, prot);
+	hyp_spin_unlock(&pkvm_pgd_lock);
 
-	return __pkvm_create_mappings(start, end - start, back, PAGE_HYP);
+	return ret;
+}
+
+int hyp_back_vmemmap(phys_addr_t back)
+{
+	unsigned long i, start, size, end = 0;
+	int ret;
+
+	for (i = 0; i < hyp_memblock_nr; i++) {
+		start = hyp_memory[i].base;
+		start = ALIGN_DOWN((u64)hyp_phys_to_page(start), PAGE_SIZE);
+		/*
+		 * The beginning of the hyp_vmemmap region for the current
+		 * memblock may already be backed by the page backing the end
+		 * the previous region, so avoid mapping it twice.
+		 */
+		start = max(start, end);
+
+		end = hyp_memory[i].base + hyp_memory[i].size;
+		end = PAGE_ALIGN((u64)hyp_phys_to_page(end));
+		if (start >= end)
+			continue;
+
+		size = end - start;
+		ret = __pkvm_create_mappings(start, size, back, PAGE_HYP);
+		if (ret)
+			return ret;
+
+		memset(hyp_phys_to_virt(back), 0, size);
+		back += size;
+	}
+
+	return 0;
 }
 
 static void *__hyp_bp_vect_base;
@@ -130,23 +210,202 @@ int pkvm_cpu_set_vector(enum arm64_hyp_spectre_vector slot)
 int hyp_map_vectors(void)
 {
 	phys_addr_t phys;
-	void *bp_base;
+	unsigned long bp_base;
+	int ret;
 
-	if (!cpus_have_const_cap(ARM64_SPECTRE_V3A))
+	if (!kvm_system_needs_idmapped_vectors()) {
+		__hyp_bp_vect_base = __bp_harden_hyp_vecs;
 		return 0;
+	}
 
 	phys = __hyp_pa(__bp_harden_hyp_vecs);
-	bp_base = (void *)__pkvm_create_private_mapping(phys,
-							__BP_HARDEN_HYP_VECS_SZ,
-							PAGE_HYP_EXEC);
-	if (IS_ERR_OR_NULL(bp_base))
-		return PTR_ERR(bp_base);
+	ret = __pkvm_create_private_mapping(phys, __BP_HARDEN_HYP_VECS_SZ,
+					    PAGE_HYP_EXEC, &bp_base);
+	if (ret)
+		return ret;
+
+	__hyp_bp_vect_base = (void *)bp_base;
+
+	return 0;
+}
+
+static void *fixmap_map_slot(struct hyp_fixmap_slot *slot, phys_addr_t phys)
+{
+	kvm_pte_t pte, *ptep = slot->ptep;
+
+	pte = *ptep;
+	pte &= ~kvm_phys_to_pte(KVM_PHYS_INVALID);
+	pte |= kvm_phys_to_pte(phys) | KVM_PTE_VALID;
+	WRITE_ONCE(*ptep, pte);
+	dsb(ishst);
+
+	return (void *)slot->addr;
+}
+
+void *hyp_fixmap_map(phys_addr_t phys)
+{
+	return fixmap_map_slot(this_cpu_ptr(&fixmap_slots), phys);
+}
+
+static void fixmap_clear_slot(struct hyp_fixmap_slot *slot)
+{
+	kvm_pte_t *ptep = slot->ptep;
+	u64 addr = slot->addr;
+	u32 level;
+
+	if (FIELD_GET(KVM_PTE_TYPE, *ptep) == KVM_PTE_TYPE_PAGE)
+		level = KVM_PGTABLE_LAST_LEVEL;
+	else
+		level = KVM_PGTABLE_LAST_LEVEL - 1; /* create_fixblock() guarantees PMD level */
+
+	WRITE_ONCE(*ptep, *ptep & ~KVM_PTE_VALID);
+
+	/*
+	 * Irritatingly, the architecture requires that we use inner-shareable
+	 * broadcast TLB invalidation here in case another CPU speculates
+	 * through our fixmap and decides to create an "amalagamation of the
+	 * values held in the TLB" due to the apparent lack of a
+	 * break-before-make sequence.
+	 *
+	 * https://lore.kernel.org/kvm/20221017115209.2099-1-will@kernel.org/T/#mf10dfbaf1eaef9274c581b81c53758918c1d0f03
+	 */
+	dsb(ishst);
+	__tlbi_level(vale2is, __TLBI_VADDR(addr, 0), level);
+	dsb(ish);
+	isb();
+}
+
+void hyp_fixmap_unmap(void)
+{
+	fixmap_clear_slot(this_cpu_ptr(&fixmap_slots));
+}
+
+static int __create_fixmap_slot_cb(const struct kvm_pgtable_visit_ctx *ctx,
+				   enum kvm_pgtable_walk_flags visit)
+{
+	struct hyp_fixmap_slot *slot = (struct hyp_fixmap_slot *)ctx->arg;
+
+	if (!kvm_pte_valid(ctx->old) || (ctx->end - ctx->start) != kvm_granule_size(ctx->level))
+		return -EINVAL;
 
-	__hyp_bp_vect_base = bp_base;
+	slot->addr = ctx->addr;
+	slot->ptep = ctx->ptep;
+
+	/*
+	 * Clear the PTE, but keep the page-table page refcount elevated to
+	 * prevent it from ever being freed. This lets us manipulate the PTEs
+	 * by hand safely without ever needing to allocate memory.
+	 */
+	fixmap_clear_slot(slot);
 
 	return 0;
 }
 
+static int create_fixmap_slot(u64 addr, u64 cpu)
+{
+	struct kvm_pgtable_walker walker = {
+		.cb	= __create_fixmap_slot_cb,
+		.flags	= KVM_PGTABLE_WALK_LEAF,
+		.arg	= per_cpu_ptr(&fixmap_slots, cpu),
+	};
+
+	return kvm_pgtable_walk(&pkvm_pgtable, addr, PAGE_SIZE, &walker);
+}
+
+#if PAGE_SHIFT < 16
+#define HAS_FIXBLOCK
+static struct hyp_fixmap_slot hyp_fixblock_slot;
+static DEFINE_HYP_SPINLOCK(hyp_fixblock_lock);
+#endif
+
+static int create_fixblock(void)
+{
+#ifdef HAS_FIXBLOCK
+	struct kvm_pgtable_walker walker = {
+		.cb	= __create_fixmap_slot_cb,
+		.flags	= KVM_PGTABLE_WALK_LEAF,
+		.arg	= &hyp_fixblock_slot,
+	};
+	unsigned long addr;
+	phys_addr_t phys;
+	int ret, i;
+
+	/* Find a RAM phys address, PMD aligned */
+	for (i = 0; i < hyp_memblock_nr; i++) {
+		phys = ALIGN(hyp_memory[i].base, PMD_SIZE);
+		if (phys + PMD_SIZE < (hyp_memory[i].base + hyp_memory[i].size))
+			break;
+	}
+
+	if (i >= hyp_memblock_nr)
+		return -EINVAL;
+
+	hyp_spin_lock(&pkvm_pgd_lock);
+	addr = ALIGN(__io_map_base, PMD_SIZE);
+	ret = __pkvm_alloc_private_va_range(addr, PMD_SIZE);
+	if (ret)
+		goto unlock;
+
+	ret = kvm_pgtable_hyp_map(&pkvm_pgtable, addr, PMD_SIZE, phys, PAGE_HYP);
+	if (ret)
+		goto unlock;
+
+	ret = kvm_pgtable_walk(&pkvm_pgtable, addr, PMD_SIZE, &walker);
+
+unlock:
+	hyp_spin_unlock(&pkvm_pgd_lock);
+
+	return ret;
+#else
+	return 0;
+#endif
+}
+
+void *hyp_fixblock_map(phys_addr_t phys, size_t *size)
+{
+#ifdef HAS_FIXBLOCK
+	*size = PMD_SIZE;
+	hyp_spin_lock(&hyp_fixblock_lock);
+	return fixmap_map_slot(&hyp_fixblock_slot, phys);
+#else
+	*size = PAGE_SIZE;
+	return hyp_fixmap_map(phys);
+#endif
+}
+
+void hyp_fixblock_unmap(void)
+{
+#ifdef HAS_FIXBLOCK
+	fixmap_clear_slot(&hyp_fixblock_slot);
+	hyp_spin_unlock(&hyp_fixblock_lock);
+#else
+	hyp_fixmap_unmap();
+#endif
+}
+
+int hyp_create_fixmap(void)
+{
+	unsigned long addr, i;
+	int ret;
+
+	for (i = 0; i < hyp_nr_cpus; i++) {
+		ret = pkvm_alloc_private_va_range(PAGE_SIZE, &addr);
+		if (ret)
+			return ret;
+
+		ret = kvm_pgtable_hyp_map(&pkvm_pgtable, addr, PAGE_SIZE,
+					  __hyp_pa(__hyp_bss_start), PAGE_HYP);
+		if (ret)
+			return ret;
+
+		ret = create_fixmap_slot(addr, i);
+		if (ret)
+			return ret;
+	}
+
+	return create_fixblock();
+}
+
 int hyp_create_idmap(u32 hyp_va_bits)
 {
 	unsigned long start, end;
@@ -171,3 +430,75 @@ int hyp_create_idmap(u32 hyp_va_bits)
 
 	return __pkvm_create_mappings(start, end - start, start, PAGE_HYP_EXEC);
 }
+
+int pkvm_create_stack(phys_addr_t phys, unsigned long *haddr)
+{
+	unsigned long addr, prev_base;
+	size_t size;
+	int ret;
+
+	hyp_spin_lock(&pkvm_pgd_lock);
+
+	prev_base = __io_map_base;
+	/*
+	 * Efficient stack verification using the NVHE_STACK_SHIFT bit implies
+	 * an alignment of our allocation on the order of the size.
+	 */
+	size = NVHE_STACK_SIZE * 2;
+	addr = ALIGN(__io_map_base, size);
+
+	ret = __pkvm_alloc_private_va_range(addr, size);
+	if (!ret) {
+		/*
+		 * Since the stack grows downwards, map the stack to the page
+		 * at the higher address and leave the lower guard page
+		 * unbacked.
+		 *
+		 * Any valid stack address now has the NVHE_STACK_SHIFT bit as 1
+		 * and addresses corresponding to the guard page have the
+		 * NVHE_STACK_SHIFT bit as 0 - this is used for overflow detection.
+		 */
+		ret = kvm_pgtable_hyp_map(&pkvm_pgtable, addr + NVHE_STACK_SIZE,
+					  NVHE_STACK_SIZE, phys, PAGE_HYP);
+		if (ret)
+			__io_map_base = prev_base;
+	}
+	hyp_spin_unlock(&pkvm_pgd_lock);
+
+	*haddr = addr + size;
+
+	return ret;
+}
+
+static void *admit_host_page(void *arg)
+{
+	struct kvm_hyp_memcache *host_mc = arg;
+
+	if (!host_mc->nr_pages)
+		return NULL;
+
+	/*
+	 * The host still owns the pages in its memcache, so we need to go
+	 * through a full host-to-hyp donation cycle to change it. Fortunately,
+	 * __pkvm_host_donate_hyp() takes care of races for us, so if it
+	 * succeeds we're good to go.
+	 */
+	if (__pkvm_host_donate_hyp(hyp_phys_to_pfn(host_mc->head), 1))
+		return NULL;
+
+	return pop_hyp_memcache(host_mc, hyp_phys_to_virt);
+}
+
+/* Refill our local memcache by popping pages from the one provided by the host. */
+int refill_memcache(struct kvm_hyp_memcache *mc, unsigned long min_pages,
+		    struct kvm_hyp_memcache *host_mc)
+{
+	struct kvm_hyp_memcache tmp = *host_mc;
+	int ret;
+
+	ret =  __topup_hyp_memcache(mc, min_pages, admit_host_page,
+				    hyp_virt_to_phys, &tmp);
+	*host_mc = tmp;
+
+	return ret;
+}