diff options
Diffstat (limited to 'arch/arm/kvm/mmu.c')
-rw-r--r-- | arch/arm/kvm/mmu.c | 223 |
1 files changed, 185 insertions, 38 deletions
diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c index b0de86b..3719583 100644 --- a/arch/arm/kvm/mmu.c +++ b/arch/arm/kvm/mmu.c @@ -19,6 +19,7 @@ #include <linux/mman.h> #include <linux/kvm_host.h> #include <linux/io.h> +#include <linux/hugetlb.h> #include <trace/events/kvm.h> #include <asm/pgalloc.h> #include <asm/cacheflush.h> @@ -41,6 +42,8 @@ static unsigned long hyp_idmap_start; static unsigned long hyp_idmap_end; static phys_addr_t hyp_idmap_vector; +#define kvm_pmd_huge(_x) (pmd_huge(_x) || pmd_trans_huge(_x)) + static void kvm_tlb_flush_vmid_ipa(struct kvm *kvm, phys_addr_t ipa) { /* @@ -93,19 +96,29 @@ static bool page_empty(void *ptr) static void clear_pud_entry(struct kvm *kvm, pud_t *pud, phys_addr_t addr) { - pmd_t *pmd_table = pmd_offset(pud, 0); - pud_clear(pud); - kvm_tlb_flush_vmid_ipa(kvm, addr); - pmd_free(NULL, pmd_table); + if (pud_huge(*pud)) { + pud_clear(pud); + kvm_tlb_flush_vmid_ipa(kvm, addr); + } else { + pmd_t *pmd_table = pmd_offset(pud, 0); + pud_clear(pud); + kvm_tlb_flush_vmid_ipa(kvm, addr); + pmd_free(NULL, pmd_table); + } put_page(virt_to_page(pud)); } static void clear_pmd_entry(struct kvm *kvm, pmd_t *pmd, phys_addr_t addr) { - pte_t *pte_table = pte_offset_kernel(pmd, 0); - pmd_clear(pmd); - kvm_tlb_flush_vmid_ipa(kvm, addr); - pte_free_kernel(NULL, pte_table); + if (kvm_pmd_huge(*pmd)) { + pmd_clear(pmd); + kvm_tlb_flush_vmid_ipa(kvm, addr); + } else { + pte_t *pte_table = pte_offset_kernel(pmd, 0); + pmd_clear(pmd); + kvm_tlb_flush_vmid_ipa(kvm, addr); + pte_free_kernel(NULL, pte_table); + } put_page(virt_to_page(pmd)); } @@ -136,18 +149,32 @@ static void unmap_range(struct kvm *kvm, pgd_t *pgdp, continue; } + if (pud_huge(*pud)) { + /* + * If we are dealing with a huge pud, just clear it and + * move on. + */ + clear_pud_entry(kvm, pud, addr); + addr = pud_addr_end(addr, end); + continue; + } + pmd = pmd_offset(pud, addr); if (pmd_none(*pmd)) { addr = pmd_addr_end(addr, end); continue; } - pte = pte_offset_kernel(pmd, addr); - clear_pte_entry(kvm, pte, addr); - next = addr + PAGE_SIZE; + if (!kvm_pmd_huge(*pmd)) { + pte = pte_offset_kernel(pmd, addr); + clear_pte_entry(kvm, pte, addr); + next = addr + PAGE_SIZE; + } - /* If we emptied the pte, walk back up the ladder */ - if (page_empty(pte)) { + /* + * If the pmd entry is to be cleared, walk back up the ladder + */ + if (kvm_pmd_huge(*pmd) || page_empty(pte)) { clear_pmd_entry(kvm, pmd, addr); next = pmd_addr_end(addr, end); if (page_empty(pmd) && !page_empty(pud)) { @@ -420,29 +447,71 @@ void kvm_free_stage2_pgd(struct kvm *kvm) kvm->arch.pgd = NULL; } - -static int stage2_set_pte(struct kvm *kvm, struct kvm_mmu_memory_cache *cache, - phys_addr_t addr, const pte_t *new_pte, bool iomap) +static pmd_t *stage2_get_pmd(struct kvm *kvm, struct kvm_mmu_memory_cache *cache, + phys_addr_t addr) { pgd_t *pgd; pud_t *pud; pmd_t *pmd; - pte_t *pte, old_pte; - /* Create 2nd stage page table mapping - Level 1 */ pgd = kvm->arch.pgd + pgd_index(addr); pud = pud_offset(pgd, addr); if (pud_none(*pud)) { if (!cache) - return 0; /* ignore calls from kvm_set_spte_hva */ + return NULL; pmd = mmu_memory_cache_alloc(cache); pud_populate(NULL, pud, pmd); get_page(virt_to_page(pud)); } - pmd = pmd_offset(pud, addr); + return pmd_offset(pud, addr); +} + +static int stage2_set_pmd_huge(struct kvm *kvm, struct kvm_mmu_memory_cache + *cache, phys_addr_t addr, const pmd_t *new_pmd) +{ + pmd_t *pmd, old_pmd; + + 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; + kvm_set_pmd(pmd, *new_pmd); + if (pmd_present(old_pmd)) + kvm_tlb_flush_vmid_ipa(kvm, addr); + else + get_page(virt_to_page(pmd)); + return 0; +} + +static int stage2_set_pte(struct kvm *kvm, struct kvm_mmu_memory_cache *cache, + phys_addr_t addr, const pte_t *new_pte, bool iomap) +{ + pmd_t *pmd; + pte_t *pte, old_pte; - /* Create 2nd stage page table mapping - Level 2 */ + /* Create stage-2 page table mapping - Level 1 */ + pmd = stage2_get_pmd(kvm, cache, addr); + if (!pmd) { + /* + * Ignore calls from kvm_set_spte_hva for unallocated + * address ranges. + */ + return 0; + } + + /* Create stage-2 page mappings - Level 2 */ if (pmd_none(*pmd)) { if (!cache) return 0; /* ignore calls from kvm_set_spte_hva */ @@ -507,16 +576,60 @@ out: return ret; } +static bool transparent_hugepage_adjust(pfn_t *pfnp, phys_addr_t *ipap) +{ + pfn_t pfn = *pfnp; + gfn_t gfn = *ipap >> PAGE_SHIFT; + + if (PageTransCompound(pfn_to_page(pfn))) { + unsigned long mask; + /* + * The address we faulted on is backed by a transparent huge + * page. However, because we map the compound huge page and + * not the individual tail page, we need to transfer the + * refcount to the head page. We have to be careful that the + * THP doesn't start to split while we are adjusting the + * refcounts. + * + * We are sure this doesn't happen, because mmu_notifier_retry + * was successful and we are holding the mmu_lock, so if this + * THP is trying to split, it will be blocked in the mmu + * notifier before touching any of the pages, specifically + * before being able to call __split_huge_page_refcount(). + * + * We can therefore safely transfer the refcount from PG_tail + * to PG_head and switch the pfn from a tail page to the head + * page accordingly. + */ + mask = PTRS_PER_PMD - 1; + VM_BUG_ON((gfn & mask) != (pfn & mask)); + if (pfn & mask) { + *ipap &= PMD_MASK; + kvm_release_pfn_clean(pfn); + pfn &= ~mask; + kvm_get_pfn(pfn); + *pfnp = pfn; + } + + return true; + } + + return false; +} + static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, - gfn_t gfn, struct kvm_memory_slot *memslot, + struct kvm_memory_slot *memslot, unsigned long fault_status) { - pte_t new_pte; - pfn_t pfn; int ret; - bool write_fault, writable; + bool write_fault, writable, hugetlb = false, force_pte = false; unsigned long mmu_seq; + gfn_t gfn = fault_ipa >> PAGE_SHIFT; + unsigned long hva = gfn_to_hva(vcpu->kvm, gfn); + struct kvm *kvm = vcpu->kvm; struct kvm_mmu_memory_cache *memcache = &vcpu->arch.mmu_page_cache; + struct vm_area_struct *vma; + pfn_t pfn; write_fault = kvm_is_write_fault(kvm_vcpu_get_hsr(vcpu)); if (fault_status == FSC_PERM && !write_fault) { @@ -524,6 +637,26 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, return -EFAULT; } + /* Let's check if we will get back a huge page backed by hugetlbfs */ + down_read(¤t->mm->mmap_sem); + vma = find_vma_intersection(current->mm, hva, hva + 1); + if (is_vm_hugetlb_page(vma)) { + hugetlb = true; + gfn = (fault_ipa & PMD_MASK) >> PAGE_SHIFT; + } else { + /* + * Pages belonging to VMAs not aligned to the PMD mapping + * granularity cannot be mapped using block descriptors even + * if the pages belong to a THP for the process, because the + * stage-2 block descriptor will cover more than a single THP + * and we loose atomicity for unmapping, updates, and splits + * of the THP or other pages in the stage-2 block range. + */ + if (vma->vm_start & ~PMD_MASK) + force_pte = true; + } + up_read(¤t->mm->mmap_sem); + /* We need minimum second+third level pages */ ret = mmu_topup_memory_cache(memcache, 2, KVM_NR_MEM_OBJS); if (ret) @@ -541,26 +674,40 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, */ smp_rmb(); - pfn = gfn_to_pfn_prot(vcpu->kvm, gfn, write_fault, &writable); + pfn = gfn_to_pfn_prot(kvm, gfn, write_fault, &writable); if (is_error_pfn(pfn)) return -EFAULT; - new_pte = pfn_pte(pfn, PAGE_S2); - coherent_icache_guest_page(vcpu->kvm, gfn); - - spin_lock(&vcpu->kvm->mmu_lock); - if (mmu_notifier_retry(vcpu->kvm, mmu_seq)) + spin_lock(&kvm->mmu_lock); + if (mmu_notifier_retry(kvm, mmu_seq)) goto out_unlock; - if (writable) { - kvm_set_s2pte_writable(&new_pte); - kvm_set_pfn_dirty(pfn); + if (!hugetlb && !force_pte) + hugetlb = transparent_hugepage_adjust(&pfn, &fault_ipa); + + if (hugetlb) { + pmd_t new_pmd = pfn_pmd(pfn, PAGE_S2); + new_pmd = pmd_mkhuge(new_pmd); + if (writable) { + kvm_set_s2pmd_writable(&new_pmd); + kvm_set_pfn_dirty(pfn); + } + coherent_icache_guest_page(kvm, hva & PMD_MASK, PMD_SIZE); + ret = stage2_set_pmd_huge(kvm, memcache, fault_ipa, &new_pmd); + } else { + pte_t new_pte = pfn_pte(pfn, PAGE_S2); + if (writable) { + kvm_set_s2pte_writable(&new_pte); + kvm_set_pfn_dirty(pfn); + } + coherent_icache_guest_page(kvm, hva, PAGE_SIZE); + ret = stage2_set_pte(kvm, memcache, fault_ipa, &new_pte, false); } - stage2_set_pte(vcpu->kvm, memcache, fault_ipa, &new_pte, false); + out_unlock: - spin_unlock(&vcpu->kvm->mmu_lock); + spin_unlock(&kvm->mmu_lock); kvm_release_pfn_clean(pfn); - return 0; + return ret; } /** @@ -629,7 +776,7 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu, struct kvm_run *run) memslot = gfn_to_memslot(vcpu->kvm, gfn); - ret = user_mem_abort(vcpu, fault_ipa, gfn, memslot, fault_status); + ret = user_mem_abort(vcpu, fault_ipa, memslot, fault_status); if (ret == 0) ret = 1; out_unlock: |