diff options
Diffstat (limited to 'arch/mips/kvm/mmu.c')
| -rw-r--r-- | arch/mips/kvm/mmu.c | 74 |
1 files changed, 70 insertions, 4 deletions
diff --git a/arch/mips/kvm/mmu.c b/arch/mips/kvm/mmu.c index 63a6d542ecb3..7962eea4ebc3 100644 --- a/arch/mips/kvm/mmu.c +++ b/arch/mips/kvm/mmu.c @@ -451,6 +451,58 @@ void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm, } /** + * _kvm_mips_map_page_fast() - Fast path GPA fault handler. + * @vcpu: VCPU pointer. + * @gpa: Guest physical address of fault. + * @write_fault: Whether the fault was due to a write. + * @out_entry: New PTE for @gpa (written on success unless NULL). + * @out_buddy: New PTE for @gpa's buddy (written on success unless + * NULL). + * + * Perform fast path GPA fault handling, doing all that can be done without + * calling into KVM. This handles dirtying of clean pages (for dirty page + * logging). + * + * Returns: 0 on success, in which case we can update derived mappings and + * resume guest execution. + * -EFAULT on failure due to absent GPA mapping or write to + * read-only page, in which case KVM must be consulted. + */ +static int _kvm_mips_map_page_fast(struct kvm_vcpu *vcpu, unsigned long gpa, + bool write_fault, + pte_t *out_entry, pte_t *out_buddy) +{ + struct kvm *kvm = vcpu->kvm; + gfn_t gfn = gpa >> PAGE_SHIFT; + pte_t *ptep; + int ret = 0; + + spin_lock(&kvm->mmu_lock); + + /* Fast path - just check GPA page table for an existing entry */ + ptep = kvm_mips_pte_for_gpa(kvm, NULL, gpa); + if (!ptep || !pte_present(*ptep)) { + ret = -EFAULT; + goto out; + } + + if (write_fault && !pte_dirty(*ptep)) { + /* Track dirtying of pages */ + set_pte(ptep, pte_mkdirty(*ptep)); + mark_page_dirty(kvm, gfn); + } + + if (out_entry) + *out_entry = *ptep; + if (out_buddy) + *out_buddy = *ptep_buddy(ptep); + +out: + spin_unlock(&kvm->mmu_lock); + return ret; +} + +/** * kvm_mips_map_page() - Map a guest physical page. * @vcpu: VCPU pointer. * @gpa: Guest physical address of fault. @@ -462,9 +514,9 @@ void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm, * Handle GPA faults by creating a new GPA mapping (or updating an existing * one). * - * This takes care of asking KVM for the corresponding PFN, and creating a - * mapping in the GPA page tables. Derived mappings (GVA page tables and TLBs) - * must be handled by the caller. + * This takes care of marking pages dirty (dirty page tracking), asking KVM for + * the corresponding PFN, and creating a mapping in the GPA page tables. Derived + * mappings (GVA page tables and TLBs) must be handled by the caller. * * Returns: 0 on success, in which case the caller may use the @out_entry * and @out_buddy PTEs to update derived mappings and resume guest @@ -485,7 +537,12 @@ static int kvm_mips_map_page(struct kvm_vcpu *vcpu, unsigned long gpa, pte_t *ptep, entry, old_pte; unsigned long prot_bits; + /* Try the fast path to handle clean pages */ srcu_idx = srcu_read_lock(&kvm->srcu); + err = _kvm_mips_map_page_fast(vcpu, gpa, write_fault, out_entry, + out_buddy); + if (!err) + goto out; /* We need a minimum of cached pages ready for page table creation */ err = mmu_topup_memory_cache(memcache, KVM_MMU_CACHE_MIN_PAGES, @@ -493,6 +550,7 @@ static int kvm_mips_map_page(struct kvm_vcpu *vcpu, unsigned long gpa, if (err) goto out; + /* Slow path - ask KVM core whether we can access this GPA */ pfn = gfn_to_pfn(kvm, gfn); if (is_error_noslot_pfn(pfn)) { @@ -502,11 +560,19 @@ static int kvm_mips_map_page(struct kvm_vcpu *vcpu, unsigned long gpa, spin_lock(&kvm->mmu_lock); + /* Ensure page tables are allocated */ ptep = kvm_mips_pte_for_gpa(kvm, memcache, gpa); - prot_bits = __READABLE | _PAGE_PRESENT | __WRITEABLE; + /* Set up the PTE */ + prot_bits = __READABLE | _PAGE_PRESENT | _PAGE_WRITE | + _page_cachable_default; + if (write_fault) { + prot_bits |= __WRITEABLE; + mark_page_dirty(kvm, gfn); + } entry = pfn_pte(pfn, __pgprot(prot_bits)); + /* Write the PTE */ old_pte = *ptep; set_pte(ptep, entry); if (pte_present(old_pte)) |