UbiquitousOS
/
OpenCloudOS-Kernel
mirror of https://gitee.com/OpenCloudOS/OpenCloudOS-Kernel.git
11
0
Fork 0
Code Issues Projects Releases Wiki Activity

KVM: arm64: Walk userspace page tables to compute the THP mapping size 

We currently rely on the kvm_is_transparent_hugepage() helper to
discover whether a given page has the potential to be mapped as
a block mapping.

However, this API doesn't really give un everything we want:
- we don't get the size: this is not crucial today as we only
  support PMD-sized THPs, but we'd like to have larger sizes
  in the future
- we're the only user left of the API, and there is a will
  to remove it altogether

To address the above, implement a simple walker using the existing
page table infrastructure, and plumb it into transparent_hugepage_adjust().
No new page sizes are supported in the process.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com>
Link: https://lore.kernel.org/r/20210726153552.1535838-3-maz@kernel.org
This commit is contained in:
Marc Zyngier 2021-07-26 16:35:48 +01:00
parent 63db506e07
commit 6011cf68c8
1 changed files with 30 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

34
arch/arm64/kvm/mmu.c
View File

@ -433,6 +433,32 @@ int create_hyp_exec_mappings(phys_addr_t phys_addr, size_t size,
return 0;
}
static struct kvm_pgtable_mm_ops kvm_user_mm_ops = {
/* We shouldn't need any other callback to walk the PT */
.phys_to_virt = kvm_host_va,
};
static int get_user_mapping_size(struct kvm *kvm, u64 addr)
{
struct kvm_pgtable pgt = {
.pgd = (kvm_pte_t *)kvm->mm->pgd,
.ia_bits = VA_BITS,
.start_level = (KVM_PGTABLE_MAX_LEVELS -
CONFIG_PGTABLE_LEVELS),
.mm_ops = &kvm_user_mm_ops,
};
kvm_pte_t pte = 0; /* Keep GCC quiet... */
u32 level = ~0;
int ret;
ret = kvm_pgtable_get_leaf(&pgt, addr, &pte, &level);
VM_BUG_ON(ret);
VM_BUG_ON(level >= KVM_PGTABLE_MAX_LEVELS);
VM_BUG_ON(!(pte & PTE_VALID));
return BIT(ARM64_HW_PGTABLE_LEVEL_SHIFT(level));
}
static struct kvm_pgtable_mm_ops kvm_s2_mm_ops = {
.zalloc_page = stage2_memcache_zalloc_page,
.zalloc_pages_exact = kvm_host_zalloc_pages_exact,
@ -780,7 +806,7 @@ static bool fault_supports_stage2_huge_mapping(struct kvm_memory_slot *memslot,
* Returns the size of the mapping.
*/
static unsigned long
transparent_hugepage_adjust(struct kvm_memory_slot *memslot,
transparent_hugepage_adjust(struct kvm *kvm, struct kvm_memory_slot *memslot,
unsigned long hva, kvm_pfn_t *pfnp,
phys_addr_t *ipap)
{
@ -791,8 +817,8 @@ transparent_hugepage_adjust(struct kvm_memory_slot *memslot,
* sure that the HVA and IPA are sufficiently aligned and that the
* block map is contained within the memslot.
*/
if (kvm_is_transparent_hugepage(pfn) &&
fault_supports_stage2_huge_mapping(memslot, hva, PMD_SIZE)) {
if (fault_supports_stage2_huge_mapping(memslot, hva, PMD_SIZE) &&
get_user_mapping_size(kvm, hva) >= PMD_SIZE) {
/*
* The address we faulted on is backed by a transparent huge
* page. However, because we map the compound huge page and
@ -1051,7 +1077,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
* backed by a THP and thus use block mapping if possible.
*/
if (vma_pagesize == PAGE_SIZE && !(force_pte || device))
vma_pagesize = transparent_hugepage_adjust(memslot, hva,
vma_pagesize = transparent_hugepage_adjust(kvm, memslot, hva,
&pfn, &fault_ipa);
if (fault_status != FSC_PERM && !device && kvm_has_mte(kvm)) {