diff options
Diffstat (limited to 'virt/kvm/arm/mmu.c')
| -rw-r--r-- | virt/kvm/arm/mmu.c | 87 |
1 files changed, 68 insertions, 19 deletions
diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c index 1d90d79706bd..91aaf73b00df 100644 --- a/virt/kvm/arm/mmu.c +++ b/virt/kvm/arm/mmu.c @@ -177,6 +177,35 @@ static void clear_stage2_pmd_entry(struct kvm *kvm, pmd_t *pmd, phys_addr_t addr put_page(virt_to_page(pmd)); } +static inline void kvm_set_pte(pte_t *ptep, pte_t new_pte) +{ + WRITE_ONCE(*ptep, new_pte); + dsb(ishst); +} + +static inline void kvm_set_pmd(pmd_t *pmdp, pmd_t new_pmd) +{ + WRITE_ONCE(*pmdp, new_pmd); + dsb(ishst); +} + +static inline void kvm_pmd_populate(pmd_t *pmdp, pte_t *ptep) +{ + kvm_set_pmd(pmdp, kvm_mk_pmd(ptep)); +} + +static inline void kvm_pud_populate(pud_t *pudp, pmd_t *pmdp) +{ + WRITE_ONCE(*pudp, kvm_mk_pud(pmdp)); + dsb(ishst); +} + +static inline void kvm_pgd_populate(pgd_t *pgdp, pud_t *pudp) +{ + WRITE_ONCE(*pgdp, kvm_mk_pgd(pudp)); + dsb(ishst); +} + /* * Unmapping vs dcache management: * @@ -196,6 +225,10 @@ static void clear_stage2_pmd_entry(struct kvm *kvm, pmd_t *pmd, phys_addr_t addr * This is why right after unmapping a page/section and invalidating * the corresponding TLBs, we call kvm_flush_dcache_p*() to make sure * the IO subsystem will never hit in the cache. + * + * This is all avoided on systems that have ARM64_HAS_STAGE2_FWB, as + * we then fully enforce cacheability of RAM, no matter what the guest + * does. */ static void unmap_stage2_ptes(struct kvm *kvm, pmd_t *pmd, phys_addr_t addr, phys_addr_t end) @@ -576,7 +609,6 @@ static void create_hyp_pte_mappings(pmd_t *pmd, unsigned long start, pte = pte_offset_kernel(pmd, addr); kvm_set_pte(pte, pfn_pte(pfn, prot)); get_page(virt_to_page(pte)); - kvm_flush_dcache_to_poc(pte, sizeof(*pte)); pfn++; } while (addr += PAGE_SIZE, addr != end); } @@ -601,9 +633,8 @@ static int create_hyp_pmd_mappings(pud_t *pud, unsigned long start, kvm_err("Cannot allocate Hyp pte\n"); return -ENOMEM; } - pmd_populate_kernel(NULL, pmd, pte); + kvm_pmd_populate(pmd, pte); get_page(virt_to_page(pmd)); - kvm_flush_dcache_to_poc(pmd, sizeof(*pmd)); } next = pmd_addr_end(addr, end); @@ -634,9 +665,8 @@ static int create_hyp_pud_mappings(pgd_t *pgd, unsigned long start, kvm_err("Cannot allocate Hyp pmd\n"); return -ENOMEM; } - pud_populate(NULL, pud, pmd); + kvm_pud_populate(pud, pmd); get_page(virt_to_page(pud)); - kvm_flush_dcache_to_poc(pud, sizeof(*pud)); } next = pud_addr_end(addr, end); @@ -671,9 +701,8 @@ static int __create_hyp_mappings(pgd_t *pgdp, unsigned long ptrs_per_pgd, err = -ENOMEM; goto out; } - pgd_populate(NULL, pgd, pud); + kvm_pgd_populate(pgd, pud); get_page(virt_to_page(pgd)); - kvm_flush_dcache_to_poc(pgd, sizeof(*pgd)); } next = pgd_addr_end(addr, end); @@ -1015,19 +1044,35 @@ static int stage2_set_pmd_huge(struct kvm *kvm, struct kvm_mmu_memory_cache pmd = stage2_get_pmd(kvm, cache, addr); VM_BUG_ON(!pmd); - /* - * Mapping in huge pages should only happen through a fault. If a - * page is merged into a transparent huge page, the individual - * subpages of that huge page should be unmapped through MMU - * notifiers before we get here. - * - * Merging of CompoundPages is not supported; they should become - * splitting first, unmapped, merged, and mapped back in on-demand. - */ - VM_BUG_ON(pmd_present(*pmd) && pmd_pfn(*pmd) != pmd_pfn(*new_pmd)); - old_pmd = *pmd; if (pmd_present(old_pmd)) { + /* + * Multiple vcpus faulting on the same PMD entry, can + * lead to them sequentially updating the PMD with the + * same value. Following the break-before-make + * (pmd_clear() followed by tlb_flush()) process can + * hinder forward progress due to refaults generated + * on missing translations. + * + * Skip updating the page table if the entry is + * unchanged. + */ + if (pmd_val(old_pmd) == pmd_val(*new_pmd)) + return 0; + + /* + * Mapping in huge pages should only happen through a + * fault. If a page is merged into a transparent huge + * page, the individual subpages of that huge page + * should be unmapped through MMU notifiers before we + * get here. + * + * Merging of CompoundPages is not supported; they + * should become splitting first, unmapped, merged, + * and mapped back in on-demand. + */ + VM_BUG_ON(pmd_pfn(old_pmd) != pmd_pfn(*new_pmd)); + pmd_clear(pmd); kvm_tlb_flush_vmid_ipa(kvm, addr); } else { @@ -1090,7 +1135,7 @@ static int stage2_set_pte(struct kvm *kvm, struct kvm_mmu_memory_cache *cache, if (!cache) return 0; /* ignore calls from kvm_set_spte_hva */ pte = mmu_memory_cache_alloc(cache); - pmd_populate_kernel(NULL, pmd, pte); + kvm_pmd_populate(pmd, pte); get_page(virt_to_page(pmd)); } @@ -1102,6 +1147,10 @@ static int stage2_set_pte(struct kvm *kvm, struct kvm_mmu_memory_cache *cache, /* Create 2nd stage page table mapping - Level 3 */ old_pte = *pte; if (pte_present(old_pte)) { + /* Skip page table update if there is no change */ + if (pte_val(old_pte) == pte_val(*new_pte)) + return 0; + kvm_set_pte(pte, __pte(0)); kvm_tlb_flush_vmid_ipa(kvm, addr); } else { |