[PATCH v3 06/32] KVM: arm64: Factor memory allocation out of pgtable.c

Quentin Perret
2021-03-03T16:05:19Z

In preparation for enabling the creation of page-tables at EL2, factor
all memory allocation out of the page-table code, hence making it
re-usable with any compatible memory allocator.

No functional changes intended.

Signed-off-by: Quentin Perret <qperret@google.com>
---
arch/arm64/include/asm/kvm_pgtable.h | 41 +++++++++++-
arch/arm64/kvm/hyp/pgtable.c | 98 +++++++++++++++++-----------
arch/arm64/kvm/mmu.c | 66 ++++++++++++++++++-
3 files changed, 163 insertions(+), 42 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
index 8886d43cfb11..3c306f90f7da 100644
--- a/arch/arm64/include/asm/kvm_pgtable.h
+++ b/arch/arm64/include/asm/kvm_pgtable.h
@@ -13,17 +13,50 @@

typedef u64 kvm_pte_t;

+/**
+ * struct kvm_pgtable_mm_ops - Memory management callbacks.
+ * @zalloc_page: Allocate a single zeroed memory page. The @arg parameter
+ * can be used by the walker to pass a memcache. The
+ * initial refcount of the page is 1.
+ * @zalloc_pages_exact: Allocate an exact number of zeroed memory pages. The
+ * @size parameter is in bytes, it is automatically rounded
+ * to PAGE_SIZE and the resulting allocation is physically
+ * contiguous.
+ * @free_pages_exact: Free an exact number of memory pages, to free memory
+ * allocated with zalloc_pages_exact.
+ * @get_page: Increment the refcount on a page.
+ * @put_page: Decrement the refcount on a page. When the refcount
+ * reaches 0 the page is automatically freed.
+ * @page_count: Return the refcount of a page.
+ * @phys_to_virt: Convert a physical address into a virtual address as
+ * accessible in the current context.
+ * @virt_to_phys: Convert a virtual address in the current context into a
+ * physical address.
+ */
+struct kvm_pgtable_mm_ops {
+ void* (*zalloc_page)(void *arg);
+ void* (*zalloc_pages_exact)(size_t size);
+ void (*free_pages_exact)(void *addr, size_t size);
+ void (*get_page)(void *addr);
+ void (*put_page)(void *addr);
+ int (*page_count)(void *addr);
+ void* (*phys_to_virt)(phys_addr_t phys);
+ phys_addr_t (*virt_to_phys)(void *addr);
+};
+
/**
* struct kvm_pgtable - KVM page-table.
* @ia_bits: Maximum input address size, in bits.
* @start_level: Level at which the page-table walk starts.
* @pgd: Pointer to the first top-level entry of the page-table.
+ * @mm_ops: Memory management callbacks.
* @mmu: Stage-2 KVM MMU struct. Unused for stage-1 page-tables.
*/
struct kvm_pgtable {
u32 ia_bits;
u32 start_level;
kvm_pte_t *pgd;
+ struct kvm_pgtable_mm_ops *mm_ops;

/* Stage-2 only */
struct kvm_s2_mmu *mmu;
@@ -86,10 +119,12 @@ struct kvm_pgtable_walker {
* kvm_pgtable_hyp_init() - Initialise a hypervisor stage-1 page-table.
* @pgt: Uninitialised page-table structure to initialise.
* @va_bits: Maximum virtual address bits.
+ * @mm_ops: Memory management callbacks.
*
* Return: 0 on success, negative error code on failure.
*/
-int kvm_pgtable_hyp_init(struct kvm_pgtable *pgt, u32 va_bits);
+int kvm_pgtable_hyp_init(struct kvm_pgtable *pgt, u32 va_bits,
+ struct kvm_pgtable_mm_ops *mm_ops);

/**
* kvm_pgtable_hyp_destroy() - Destroy an unused hypervisor stage-1 page-table.
@@ -126,10 +161,12 @@ int kvm_pgtable_hyp_map(struct kvm_pgtable *pgt, u64 addr, u64 size, u64 phys,
* kvm_pgtable_stage2_init() - Initialise a guest stage-2 page-table.
* @pgt: Uninitialised page-table structure to initialise.
* @kvm: KVM structure representing the guest virtual machine.
+ * @mm_ops: Memory management callbacks.
*
* Return: 0 on success, negative error code on failure.
*/
-int kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm *kvm);
+int kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm *kvm,
+ struct kvm_pgtable_mm_ops *mm_ops);

/**
* kvm_pgtable_stage2_destroy() - Destroy an unused guest stage-2 page-table.
diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index 81fe032f34d1..b975a67d1f85 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -152,9 +152,9 @@ static kvm_pte_t kvm_phys_to_pte(u64 pa)
return pte;
}

-static kvm_pte_t *kvm_pte_follow(kvm_pte_t pte)
+static kvm_pte_t *kvm_pte_follow(kvm_pte_t pte, struct kvm_pgtable_mm_ops *mm_ops)
{
- return __va(kvm_pte_to_phys(pte));
+ return mm_ops->phys_to_virt(kvm_pte_to_phys(pte));
}

static void kvm_set_invalid_pte(kvm_pte_t *ptep)
@@ -163,9 +163,10 @@ static void kvm_set_invalid_pte(kvm_pte_t *ptep)
WRITE_ONCE(*ptep, pte & ~KVM_PTE_VALID);
}

-static void kvm_set_table_pte(kvm_pte_t *ptep, kvm_pte_t *childp)
+static void kvm_set_table_pte(kvm_pte_t *ptep, kvm_pte_t *childp,
+ struct kvm_pgtable_mm_ops *mm_ops)
{
- kvm_pte_t old = *ptep, pte = kvm_phys_to_pte(__pa(childp));
+ kvm_pte_t old = *ptep, pte = kvm_phys_to_pte(mm_ops->virt_to_phys(childp));

pte |= FIELD_PREP(KVM_PTE_TYPE, KVM_PTE_TYPE_TABLE);
pte |= KVM_PTE_VALID;
@@ -227,7 +228,7 @@ static inline int __kvm_pgtable_visit(struct kvm_pgtable_walk_data *data,
goto out;
}

- childp = kvm_pte_follow(pte);
+ childp = kvm_pte_follow(pte, data->pgt->mm_ops);
ret = __kvm_pgtable_walk(data, childp, level + 1);
if (ret)
goto out;
@@ -302,8 +303,9 @@ int kvm_pgtable_walk(struct kvm_pgtable *pgt, u64 addr, u64 size,
}

struct hyp_map_data {
- u64 phys;
- kvm_pte_t attr;
+ u64 phys;
+ kvm_pte_t attr;
+ struct kvm_pgtable_mm_ops *mm_ops;
};

static int hyp_map_set_prot_attr(enum kvm_pgtable_prot prot,
@@ -358,6 +360,8 @@ static int hyp_map_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
enum kvm_pgtable_walk_flags flag, void * const arg)
{
kvm_pte_t *childp;
+ struct hyp_map_data *data = arg;
+ struct kvm_pgtable_mm_ops *mm_ops = data->mm_ops;

if (hyp_map_walker_try_leaf(addr, end, level, ptep, arg))
return 0;
@@ -365,11 +369,11 @@ static int hyp_map_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
if (WARN_ON(level == KVM_PGTABLE_MAX_LEVELS - 1))
return -EINVAL;

- childp = (kvm_pte_t *)get_zeroed_page(GFP_KERNEL);
+ childp = (kvm_pte_t *)mm_ops->zalloc_page(NULL);
if (!childp)
return -ENOMEM;

- kvm_set_table_pte(ptep, childp);
+ kvm_set_table_pte(ptep, childp, mm_ops);
return 0;
}

@@ -379,6 +383,7 @@ int kvm_pgtable_hyp_map(struct kvm_pgtable *pgt, u64 addr, u64 size, u64 phys,
int ret;
struct hyp_map_data map_data = {
.phys = ALIGN_DOWN(phys, PAGE_SIZE),
+ .mm_ops = pgt->mm_ops,
};
struct kvm_pgtable_walker walker = {
.cb = hyp_map_walker,
@@ -396,16 +401,18 @@ int kvm_pgtable_hyp_map(struct kvm_pgtable *pgt, u64 addr, u64 size, u64 phys,
return ret;
}

-int kvm_pgtable_hyp_init(struct kvm_pgtable *pgt, u32 va_bits)
+int kvm_pgtable_hyp_init(struct kvm_pgtable *pgt, u32 va_bits,
+ struct kvm_pgtable_mm_ops *mm_ops)
{
u64 levels = ARM64_HW_PGTABLE_LEVELS(va_bits);

- pgt->pgd = (kvm_pte_t *)get_zeroed_page(GFP_KERNEL);
+ pgt->pgd = (kvm_pte_t *)mm_ops->zalloc_page(NULL);
if (!pgt->pgd)
return -ENOMEM;

pgt->ia_bits = va_bits;
pgt->start_level = KVM_PGTABLE_MAX_LEVELS - levels;
+ pgt->mm_ops = mm_ops;
pgt->mmu = NULL;
return 0;
}
@@ -413,7 +420,9 @@ int kvm_pgtable_hyp_init(struct kvm_pgtable *pgt, u32 va_bits)
static int hyp_free_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
enum kvm_pgtable_walk_flags flag, void * const arg)
{
- put_page(virt_to_page(kvm_pte_follow(*ptep)));
+ struct kvm_pgtable_mm_ops *mm_ops = arg;
+
+ mm_ops->put_page((void *)kvm_pte_follow(*ptep, mm_ops));
return 0;
}

@@ -422,10 +431,11 @@ void kvm_pgtable_hyp_destroy(struct kvm_pgtable *pgt)
struct kvm_pgtable_walker walker = {
.cb = hyp_free_walker,
.flags = KVM_PGTABLE_WALK_TABLE_POST,
+ .arg = pgt->mm_ops,
};

WARN_ON(kvm_pgtable_walk(pgt, 0, BIT(pgt->ia_bits), &walker));
- put_page(virt_to_page(pgt->pgd));
+ pgt->mm_ops->put_page(pgt->pgd);
pgt->pgd = NULL;
}

@@ -437,6 +447,8 @@ struct stage2_map_data {

struct kvm_s2_mmu *mmu;
struct kvm_mmu_memory_cache *memcache;
+
+ struct kvm_pgtable_mm_ops *mm_ops;
};

static int stage2_map_set_prot_attr(enum kvm_pgtable_prot prot,
@@ -470,7 +482,7 @@ static int stage2_map_walker_try_leaf(u64 addr, u64 end, u32 level,
{
kvm_pte_t new, old = *ptep;
u64 granule = kvm_granule_size(level), phys = data->phys;
- struct page *page = virt_to_page(ptep);
+ struct kvm_pgtable_mm_ops *mm_ops = data->mm_ops;

if (!kvm_block_mapping_supported(addr, end, phys, level))
return -E2BIG;
@@ -492,11 +504,11 @@ static int stage2_map_walker_try_leaf(u64 addr, u64 end, u32 level,
*/
kvm_set_invalid_pte(ptep);
kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, data->mmu, addr, level);
- put_page(page);
+ mm_ops->put_page(ptep);
}

smp_store_release(ptep, new);
- get_page(page);
+ mm_ops->get_page(ptep);
data->phys += granule;
return 0;
}
@@ -526,13 +538,13 @@ static int stage2_map_walk_table_pre(u64 addr, u64 end, u32 level,
static int stage2_map_walk_leaf(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
struct stage2_map_data *data)
{
- int ret;
+ struct kvm_pgtable_mm_ops *mm_ops = data->mm_ops;
kvm_pte_t *childp, pte = *ptep;
- struct page *page = virt_to_page(ptep);
+ int ret;

if (data->anchor) {
if (kvm_pte_valid(pte))
- put_page(page);
+ mm_ops->put_page(ptep);

return 0;
}
@@ -547,7 +559,7 @@ static int stage2_map_walk_leaf(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
if (!data->memcache)
return -ENOMEM;

- childp = kvm_mmu_memory_cache_alloc(data->memcache);
+ childp = mm_ops->zalloc_page(data->memcache);
if (!childp)
return -ENOMEM;

@@ -559,11 +571,11 @@ static int stage2_map_walk_leaf(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
if (kvm_pte_valid(pte)) {
kvm_set_invalid_pte(ptep);
kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, data->mmu, addr, level);
- put_page(page);
+ mm_ops->put_page(ptep);
}

- kvm_set_table_pte(ptep, childp);
- get_page(page);
+ kvm_set_table_pte(ptep, childp, mm_ops);
+ mm_ops->get_page(ptep);

return 0;
}
@@ -572,13 +584,14 @@ static int stage2_map_walk_table_post(u64 addr, u64 end, u32 level,
kvm_pte_t *ptep,
struct stage2_map_data *data)
{
+ struct kvm_pgtable_mm_ops *mm_ops = data->mm_ops;
int ret = 0;

if (!data->anchor)
return 0;

- put_page(virt_to_page(kvm_pte_follow(*ptep)));
- put_page(virt_to_page(ptep));
+ mm_ops->put_page(kvm_pte_follow(*ptep, mm_ops));
+ mm_ops->put_page(ptep);

if (data->anchor == ptep) {
data->anchor = NULL;
@@ -633,6 +646,7 @@ int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
.phys = ALIGN_DOWN(phys, PAGE_SIZE),
.mmu = pgt->mmu,
.memcache = mc,
+ .mm_ops = pgt->mm_ops,
};
struct kvm_pgtable_walker walker = {
.cb = stage2_map_walker,
@@ -669,7 +683,9 @@ static int stage2_unmap_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
enum kvm_pgtable_walk_flags flag,
void * const arg)
{
- struct kvm_s2_mmu *mmu = arg;
+ struct kvm_pgtable *pgt = arg;
+ struct kvm_s2_mmu *mmu = pgt->mmu;
+ struct kvm_pgtable_mm_ops *mm_ops = pgt->mm_ops;
kvm_pte_t pte = *ptep, *childp = NULL;
bool need_flush = false;

@@ -677,9 +693,9 @@ static int stage2_unmap_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
return 0;

if (kvm_pte_table(pte, level)) {
- childp = kvm_pte_follow(pte);
+ childp = kvm_pte_follow(pte, mm_ops);

- if (page_count(virt_to_page(childp)) != 1)
+ if (mm_ops->page_count(childp) != 1)
return 0;
} else if (stage2_pte_cacheable(pte)) {
need_flush = true;
@@ -692,15 +708,15 @@ static int stage2_unmap_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
*/
kvm_set_invalid_pte(ptep);
kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, mmu, addr, level);
- put_page(virt_to_page(ptep));
+ mm_ops->put_page(ptep);

if (need_flush) {
- stage2_flush_dcache(kvm_pte_follow(pte),
+ stage2_flush_dcache(kvm_pte_follow(pte, mm_ops),
kvm_granule_size(level));
}

if (childp)
- put_page(virt_to_page(childp));
+ mm_ops->put_page(childp);

return 0;
}
@@ -709,7 +725,7 @@ int kvm_pgtable_stage2_unmap(struct kvm_pgtable *pgt, u64 addr, u64 size)
{
struct kvm_pgtable_walker walker = {
.cb = stage2_unmap_walker,
- .arg = pgt->mmu,
+ .arg = pgt,
.flags = KVM_PGTABLE_WALK_LEAF | KVM_PGTABLE_WALK_TABLE_POST,
};

@@ -841,12 +857,13 @@ static int stage2_flush_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
enum kvm_pgtable_walk_flags flag,
void * const arg)
{
+ struct kvm_pgtable_mm_ops *mm_ops = arg;
kvm_pte_t pte = *ptep;

if (!kvm_pte_valid(pte) || !stage2_pte_cacheable(pte))
return 0;

- stage2_flush_dcache(kvm_pte_follow(pte), kvm_granule_size(level));
+ stage2_flush_dcache(kvm_pte_follow(pte, mm_ops), kvm_granule_size(level));
return 0;
}

@@ -855,6 +872,7 @@ int kvm_pgtable_stage2_flush(struct kvm_pgtable *pgt, u64 addr, u64 size)
struct kvm_pgtable_walker walker = {
.cb = stage2_flush_walker,
.flags = KVM_PGTABLE_WALK_LEAF,
+ .arg = pgt->mm_ops,
};

if (cpus_have_const_cap(ARM64_HAS_STAGE2_FWB))
@@ -863,7 +881,8 @@ int kvm_pgtable_stage2_flush(struct kvm_pgtable *pgt, u64 addr, u64 size)
return kvm_pgtable_walk(pgt, addr, size, &walker);
}

-int kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm *kvm)
+int kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm *kvm,
+ struct kvm_pgtable_mm_ops *mm_ops)
{
size_t pgd_sz;
u64 vtcr = kvm->arch.vtcr;
@@ -872,12 +891,13 @@ int kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm *kvm)
u32 start_level = VTCR_EL2_TGRAN_SL0_BASE - sl0;

pgd_sz = kvm_pgd_pages(ia_bits, start_level) * PAGE_SIZE;
- pgt->pgd = alloc_pages_exact(pgd_sz, GFP_KERNEL_ACCOUNT | __GFP_ZERO);
+ pgt->pgd = mm_ops->zalloc_pages_exact(pgd_sz);
if (!pgt->pgd)
return -ENOMEM;

pgt->ia_bits = ia_bits;
pgt->start_level = start_level;
+ pgt->mm_ops = mm_ops;
pgt->mmu = &kvm->arch.mmu;

/* Ensure zeroed PGD pages are visible to the hardware walker */
@@ -889,15 +909,16 @@ static int stage2_free_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
enum kvm_pgtable_walk_flags flag,
void * const arg)
{
+ struct kvm_pgtable_mm_ops *mm_ops = arg;
kvm_pte_t pte = *ptep;

if (!kvm_pte_valid(pte))
return 0;

- put_page(virt_to_page(ptep));
+ mm_ops->put_page(ptep);

if (kvm_pte_table(pte, level))
- put_page(virt_to_page(kvm_pte_follow(pte)));
+ mm_ops->put_page(kvm_pte_follow(pte, mm_ops));

return 0;
}
@@ -909,10 +930,11 @@ void kvm_pgtable_stage2_destroy(struct kvm_pgtable *pgt)
.cb = stage2_free_walker,
.flags = KVM_PGTABLE_WALK_LEAF |
KVM_PGTABLE_WALK_TABLE_POST,
+ .arg = pgt->mm_ops,
};

WARN_ON(kvm_pgtable_walk(pgt, 0, BIT(pgt->ia_bits), &walker));
pgd_sz = kvm_pgd_pages(pgt->ia_bits, pgt->start_level) * PAGE_SIZE;
- free_pages_exact(pgt->pgd, pgd_sz);
+ pgt->mm_ops->free_pages_exact(pgt->pgd, pgd_sz);
pgt->pgd = NULL;
}
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 77cb2d28f2a4..4d41d7838d53 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -88,6 +88,44 @@ static bool kvm_is_device_pfn(unsigned long pfn)
return !pfn_valid(pfn);
}

+static void *stage2_memcache_zalloc_page(void *arg)
+{
+ struct kvm_mmu_memory_cache *mc = arg;
+
+ /* Allocated with __GFP_ZERO, so no need to zero */
+ return kvm_mmu_memory_cache_alloc(mc);
+}
+
+static void *kvm_host_zalloc_pages_exact(size_t size)
+{
+ return alloc_pages_exact(size, GFP_KERNEL_ACCOUNT | __GFP_ZERO);
+}
+
+static void kvm_host_get_page(void *addr)
+{
+ get_page(virt_to_page(addr));
+}
+
+static void kvm_host_put_page(void *addr)
+{
+ put_page(virt_to_page(addr));
+}
+
+static int kvm_host_page_count(void *addr)
+{
+ return page_count(virt_to_page(addr));
+}
+
+static phys_addr_t kvm_host_pa(void *addr)
+{
+ return __pa(addr);
+}
+
+static void *kvm_host_va(phys_addr_t phys)
+{
+ return __va(phys);
+}
+
/*
* Unmapping vs dcache management:
*
@@ -351,6 +389,17 @@ int create_hyp_exec_mappings(phys_addr_t phys_addr, size_t size,
return 0;
}

+static struct kvm_pgtable_mm_ops kvm_s2_mm_ops = {
+ .zalloc_page = stage2_memcache_zalloc_page,
+ .zalloc_pages_exact = kvm_host_zalloc_pages_exact,
+ .free_pages_exact = free_pages_exact,
+ .get_page = kvm_host_get_page,
+ .put_page = kvm_host_put_page,
+ .page_count = kvm_host_page_count,
+ .phys_to_virt = kvm_host_va,
+ .virt_to_phys = kvm_host_pa,
+};
+
/**
* kvm_init_stage2_mmu - Initialise a S2 MMU strucrure
* @kvm: The pointer to the KVM structure
@@ -374,7 +423,7 @@ int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu)
if (!pgt)
return -ENOMEM;

- err = kvm_pgtable_stage2_init(pgt, kvm);
+ err = kvm_pgtable_stage2_init(pgt, kvm, &kvm_s2_mm_ops);
if (err)
goto out_free_pgtable;

@@ -1208,6 +1257,19 @@ static int kvm_map_idmap_text(void)
return err;
}

+static void *kvm_hyp_zalloc_page(void *arg)
+{
+ return (void *)get_zeroed_page(GFP_KERNEL);
+}
+
+static struct kvm_pgtable_mm_ops kvm_hyp_mm_ops = {
+ .zalloc_page = kvm_hyp_zalloc_page,
+ .get_page = kvm_host_get_page,
+ .put_page = kvm_host_put_page,
+ .phys_to_virt = kvm_host_va,
+ .virt_to_phys = kvm_host_pa,
+};
+
int kvm_mmu_init(void)
{
int err;
@@ -1251,7 +1313,7 @@ int kvm_mmu_init(void)
goto out;
}

- err = kvm_pgtable_hyp_init(hyp_pgtable, hyp_va_bits);
+ err = kvm_pgtable_hyp_init(hyp_pgtable, hyp_va_bits, &kvm_hyp_mm_ops);
if (err)
goto out_free_pgtable;