KVM: arm64: Add support for stage-2 map()/unmap() in generic page-table

Add stage-2 map() and unmap() operations to the generic page-table code.

Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20200911132529.19844-7-will@kernel.org
This commit is contained in:
Will Deacon 2020-09-11 14:25:14 +01:00 committed by Marc Zyngier
parent 71233d05f4
commit 6d9d2115c4
2 changed files with 319 additions and 0 deletions

View File

@ -140,6 +140,52 @@ int kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm *kvm);
*/
void kvm_pgtable_stage2_destroy(struct kvm_pgtable *pgt);
/**
* kvm_pgtable_stage2_map() - Install a mapping in a guest stage-2 page-table.
* @pgt: Page-table structure initialised by kvm_pgtable_stage2_init().
* @addr: Intermediate physical address at which to place the mapping.
* @size: Size of the mapping.
* @phys: Physical address of the memory to map.
* @prot: Permissions and attributes for the mapping.
* @mc: Cache of pre-allocated GFP_PGTABLE_USER memory from which to
* allocate page-table pages.
*
* The offset of @addr within a page is ignored, @size is rounded-up to
* the next page boundary and @phys is rounded-down to the previous page
* boundary.
*
* If device attributes are not explicitly requested in @prot, then the
* mapping will be normal, cacheable.
*
* Note that this function will both coalesce existing table entries and split
* existing block mappings, relying on page-faults to fault back areas outside
* of the new mapping lazily.
*
* Return: 0 on success, negative error code on failure.
*/
int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
u64 phys, enum kvm_pgtable_prot prot,
struct kvm_mmu_memory_cache *mc);
/**
* kvm_pgtable_stage2_unmap() - Remove a mapping from a guest stage-2 page-table.
* @pgt: Page-table structure initialised by kvm_pgtable_stage2_init().
* @addr: Intermediate physical address from which to remove the mapping.
* @size: Size of the mapping.
*
* The offset of @addr within a page is ignored and @size is rounded-up to
* the next page boundary.
*
* TLB invalidation is performed for each page-table entry cleared during the
* unmapping operation and the reference count for the page-table page
* containing the cleared entry is decremented, with unreferenced pages being
* freed. Unmapping a cacheable page will ensure that it is clean to the PoC if
* FWB is not supported by the CPU.
*
* Return: 0 on success, negative error code on failure.
*/
int kvm_pgtable_stage2_unmap(struct kvm_pgtable *pgt, u64 addr, u64 size);
/**
* kvm_pgtable_walk() - Walk a page-table.
* @pgt: Page-table structure initialised by kvm_pgtable_*_init().

View File

@ -32,10 +32,19 @@
#define KVM_PTE_LEAF_ATTR_LO_S1_SH_IS 3
#define KVM_PTE_LEAF_ATTR_LO_S1_AF BIT(10)
#define KVM_PTE_LEAF_ATTR_LO_S2_MEMATTR GENMASK(5, 2)
#define KVM_PTE_LEAF_ATTR_LO_S2_S2AP_R BIT(6)
#define KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W BIT(7)
#define KVM_PTE_LEAF_ATTR_LO_S2_SH GENMASK(9, 8)
#define KVM_PTE_LEAF_ATTR_LO_S2_SH_IS 3
#define KVM_PTE_LEAF_ATTR_LO_S2_AF BIT(10)
#define KVM_PTE_LEAF_ATTR_HI GENMASK(63, 51)
#define KVM_PTE_LEAF_ATTR_HI_S1_XN BIT(54)
#define KVM_PTE_LEAF_ATTR_HI_S2_XN BIT(54)
struct kvm_pgtable_walk_data {
struct kvm_pgtable *pgt;
struct kvm_pgtable_walker *walker;
@ -417,6 +426,270 @@ void kvm_pgtable_hyp_destroy(struct kvm_pgtable *pgt)
pgt->pgd = NULL;
}
struct stage2_map_data {
u64 phys;
kvm_pte_t attr;
kvm_pte_t *anchor;
struct kvm_s2_mmu *mmu;
struct kvm_mmu_memory_cache *memcache;
};
static int stage2_map_set_prot_attr(enum kvm_pgtable_prot prot,
struct stage2_map_data *data)
{
bool device = prot & KVM_PGTABLE_PROT_DEVICE;
kvm_pte_t attr = device ? PAGE_S2_MEMATTR(DEVICE_nGnRE) :
PAGE_S2_MEMATTR(NORMAL);
u32 sh = KVM_PTE_LEAF_ATTR_LO_S2_SH_IS;
if (!(prot & KVM_PGTABLE_PROT_X))
attr |= KVM_PTE_LEAF_ATTR_HI_S2_XN;
else if (device)
return -EINVAL;
if (prot & KVM_PGTABLE_PROT_R)
attr |= KVM_PTE_LEAF_ATTR_LO_S2_S2AP_R;
if (prot & KVM_PGTABLE_PROT_W)
attr |= KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W;
attr |= FIELD_PREP(KVM_PTE_LEAF_ATTR_LO_S2_SH, sh);
attr |= KVM_PTE_LEAF_ATTR_LO_S2_AF;
data->attr = attr;
return 0;
}
static bool stage2_map_walker_try_leaf(u64 addr, u64 end, u32 level,
kvm_pte_t *ptep,
struct stage2_map_data *data)
{
u64 granule = kvm_granule_size(level), phys = data->phys;
if (!kvm_block_mapping_supported(addr, end, phys, level))
return false;
if (kvm_set_valid_leaf_pte(ptep, phys, data->attr, level))
goto out;
/* There's an existing valid leaf entry, so perform break-before-make */
kvm_set_invalid_pte(ptep);
kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, data->mmu, addr, level);
kvm_set_valid_leaf_pte(ptep, phys, data->attr, level);
out:
data->phys += granule;
return true;
}
static int stage2_map_walk_table_pre(u64 addr, u64 end, u32 level,
kvm_pte_t *ptep,
struct stage2_map_data *data)
{
if (data->anchor)
return 0;
if (!kvm_block_mapping_supported(addr, end, data->phys, level))
return 0;
kvm_set_invalid_pte(ptep);
kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, data->mmu, addr, 0);
data->anchor = ptep;
return 0;
}
static int stage2_map_walk_leaf(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
struct stage2_map_data *data)
{
kvm_pte_t *childp, pte = *ptep;
struct page *page = virt_to_page(ptep);
if (data->anchor) {
if (kvm_pte_valid(pte))
put_page(page);
return 0;
}
if (stage2_map_walker_try_leaf(addr, end, level, ptep, data))
goto out_get_page;
if (WARN_ON(level == KVM_PGTABLE_MAX_LEVELS - 1))
return -EINVAL;
if (!data->memcache)
return -ENOMEM;
childp = kvm_mmu_memory_cache_alloc(data->memcache);
if (!childp)
return -ENOMEM;
/*
* If we've run into an existing block mapping then replace it with
* a table. Accesses beyond 'end' that fall within the new table
* will be mapped lazily.
*/
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);
}
kvm_set_table_pte(ptep, childp);
out_get_page:
get_page(page);
return 0;
}
static int stage2_map_walk_table_post(u64 addr, u64 end, u32 level,
kvm_pte_t *ptep,
struct stage2_map_data *data)
{
int ret = 0;
if (!data->anchor)
return 0;
free_page((unsigned long)kvm_pte_follow(*ptep));
put_page(virt_to_page(ptep));
if (data->anchor == ptep) {
data->anchor = NULL;
ret = stage2_map_walk_leaf(addr, end, level, ptep, data);
}
return ret;
}
/*
* This is a little fiddly, as we use all three of the walk flags. The idea
* is that the TABLE_PRE callback runs for table entries on the way down,
* looking for table entries which we could conceivably replace with a
* block entry for this mapping. If it finds one, then it sets the 'anchor'
* field in 'struct stage2_map_data' to point at the table entry, before
* clearing the entry to zero and descending into the now detached table.
*
* The behaviour of the LEAF callback then depends on whether or not the
* anchor has been set. If not, then we're not using a block mapping higher
* up the table and we perform the mapping at the existing leaves instead.
* If, on the other hand, the anchor _is_ set, then we drop references to
* all valid leaves so that the pages beneath the anchor can be freed.
*
* Finally, the TABLE_POST callback does nothing if the anchor has not
* been set, but otherwise frees the page-table pages while walking back up
* the page-table, installing the block entry when it revisits the anchor
* pointer and clearing the anchor to NULL.
*/
static int stage2_map_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
enum kvm_pgtable_walk_flags flag, void * const arg)
{
struct stage2_map_data *data = arg;
switch (flag) {
case KVM_PGTABLE_WALK_TABLE_PRE:
return stage2_map_walk_table_pre(addr, end, level, ptep, data);
case KVM_PGTABLE_WALK_LEAF:
return stage2_map_walk_leaf(addr, end, level, ptep, data);
case KVM_PGTABLE_WALK_TABLE_POST:
return stage2_map_walk_table_post(addr, end, level, ptep, data);
}
return -EINVAL;
}
int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
u64 phys, enum kvm_pgtable_prot prot,
struct kvm_mmu_memory_cache *mc)
{
int ret;
struct stage2_map_data map_data = {
.phys = ALIGN_DOWN(phys, PAGE_SIZE),
.mmu = pgt->mmu,
.memcache = mc,
};
struct kvm_pgtable_walker walker = {
.cb = stage2_map_walker,
.flags = KVM_PGTABLE_WALK_TABLE_PRE |
KVM_PGTABLE_WALK_LEAF |
KVM_PGTABLE_WALK_TABLE_POST,
.arg = &map_data,
};
ret = stage2_map_set_prot_attr(prot, &map_data);
if (ret)
return ret;
ret = kvm_pgtable_walk(pgt, addr, size, &walker);
dsb(ishst);
return ret;
}
static void stage2_flush_dcache(void *addr, u64 size)
{
if (cpus_have_const_cap(ARM64_HAS_STAGE2_FWB))
return;
__flush_dcache_area(addr, size);
}
static bool stage2_pte_cacheable(kvm_pte_t pte)
{
u64 memattr = FIELD_GET(KVM_PTE_LEAF_ATTR_LO_S2_MEMATTR, pte);
return memattr == PAGE_S2_MEMATTR(NORMAL);
}
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;
kvm_pte_t pte = *ptep, *childp = NULL;
bool need_flush = false;
if (!kvm_pte_valid(pte))
return 0;
if (kvm_pte_table(pte, level)) {
childp = kvm_pte_follow(pte);
if (page_count(virt_to_page(childp)) != 1)
return 0;
} else if (stage2_pte_cacheable(pte)) {
need_flush = true;
}
/*
* This is similar to the map() path in that we unmap the entire
* block entry and rely on the remaining portions being faulted
* back lazily.
*/
kvm_set_invalid_pte(ptep);
kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, mmu, addr, level);
put_page(virt_to_page(ptep));
if (need_flush) {
stage2_flush_dcache(kvm_pte_follow(pte),
kvm_granule_size(level));
}
if (childp)
free_page((unsigned long)childp);
return 0;
}
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,
.flags = KVM_PGTABLE_WALK_LEAF | KVM_PGTABLE_WALK_TABLE_POST,
};
return kvm_pgtable_walk(pgt, addr, size, &walker);
}
int kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm *kvm)
{
size_t pgd_sz;