diff options
| -rw-r--r-- | arch/arm64/kvm/mmu.c | 48 |
1 files changed, 21 insertions, 27 deletions
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index 7113587222ff..f54408355d1d 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -1218,6 +1218,20 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, } /* + * Permission faults just need to update the existing leaf entry, + * and so normally don't require allocations from the memcache. The + * only exception to this is when dirty logging is enabled at runtime + * and a write fault needs to collapse a block entry into a table. + */ + if (fault_status != ESR_ELx_FSC_PERM || + (logging_active && write_fault)) { + ret = kvm_mmu_topup_memory_cache(memcache, + kvm_mmu_cache_min_pages(kvm)); + if (ret) + return ret; + } + + /* * Let's check if we will get back a huge page backed by hugetlbfs, or * get block mapping for device MMIO region. */ @@ -1269,37 +1283,17 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, fault_ipa &= ~(vma_pagesize - 1); gfn = fault_ipa >> PAGE_SHIFT; - mmap_read_unlock(current->mm); - - /* - * Permission faults just need to update the existing leaf entry, - * and so normally don't require allocations from the memcache. The - * only exception to this is when dirty logging is enabled at runtime - * and a write fault needs to collapse a block entry into a table. - */ - if (fault_status != ESR_ELx_FSC_PERM || - (logging_active && write_fault)) { - ret = kvm_mmu_topup_memory_cache(memcache, - kvm_mmu_cache_min_pages(kvm)); - if (ret) - return ret; - } - mmu_seq = vcpu->kvm->mmu_invalidate_seq; /* - * Ensure the read of mmu_invalidate_seq happens before we call - * gfn_to_pfn_prot (which calls get_user_pages), so that we don't risk - * the page we just got a reference to gets unmapped before we have a - * chance to grab the mmu_lock, which ensure that if the page gets - * unmapped afterwards, the call to kvm_unmap_gfn will take it away - * from us again properly. This smp_rmb() interacts with the smp_wmb() - * in kvm_mmu_notifier_invalidate_<page|range_end>. + * Read mmu_invalidate_seq so that KVM can detect if the results of + * vma_lookup() or __gfn_to_pfn_memslot() become stale prior to + * acquiring kvm->mmu_lock. * - * Besides, __gfn_to_pfn_memslot() instead of gfn_to_pfn_prot() is - * used to avoid unnecessary overhead introduced to locate the memory - * slot because it's always fixed even @gfn is adjusted for huge pages. + * Rely on mmap_read_unlock() for an implicit smp_rmb(), which pairs + * with the smp_wmb() in kvm_mmu_invalidate_end(). */ - smp_rmb(); + mmu_seq = vcpu->kvm->mmu_invalidate_seq; + mmap_read_unlock(current->mm); pfn = __gfn_to_pfn_memslot(memslot, gfn, false, false, NULL, write_fault, &writable, NULL); |