KVM: propagate fault r/w information to gup(), allow read-only memory
As suggested by Andrea, pass r/w error code to gup(), upgrading read fault to writable if host pte allows it. Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Marcelo Tosatti
Avi Kivity
Родитель
7905d9a5ad
Коммит
612819c3c6
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@ -2216,7 +2216,7 @@ static void direct_pte_prefetch(struct kvm_vcpu *vcpu, u64 *sptep)
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}
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static int __direct_map(struct kvm_vcpu *vcpu, gpa_t v, int write,
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int level, gfn_t gfn, pfn_t pfn)
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int map_writable, int level, gfn_t gfn, pfn_t pfn)
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{
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struct kvm_shadow_walk_iterator iterator;
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struct kvm_mmu_page *sp;
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@ -2225,9 +2225,13 @@ static int __direct_map(struct kvm_vcpu *vcpu, gpa_t v, int write,
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for_each_shadow_entry(vcpu, (u64)gfn << PAGE_SHIFT, iterator) {
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if (iterator.level == level) {
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mmu_set_spte(vcpu, iterator.sptep, ACC_ALL, ACC_ALL,
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unsigned pte_access = ACC_ALL;
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if (!map_writable)
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pte_access &= ~ACC_WRITE_MASK;
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mmu_set_spte(vcpu, iterator.sptep, ACC_ALL, pte_access,
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0, write, 1, &pt_write,
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level, gfn, pfn, false, true);
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level, gfn, pfn, false, map_writable);
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direct_pte_prefetch(vcpu, iterator.sptep);
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++vcpu->stat.pf_fixed;
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break;
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@ -2288,6 +2292,7 @@ static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, int write, gfn_t gfn)
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int level;
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pfn_t pfn;
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unsigned long mmu_seq;
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bool map_writable;
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level = mapping_level(vcpu, gfn);
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@ -2302,7 +2307,7 @@ static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, int write, gfn_t gfn)
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mmu_seq = vcpu->kvm->mmu_notifier_seq;
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smp_rmb();
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pfn = gfn_to_pfn(vcpu->kvm, gfn);
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pfn = gfn_to_pfn_prot(vcpu->kvm, gfn, write, &map_writable);
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/* mmio */
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if (is_error_pfn(pfn))
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@ -2312,7 +2317,7 @@ static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, int write, gfn_t gfn)
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if (mmu_notifier_retry(vcpu, mmu_seq))
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goto out_unlock;
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kvm_mmu_free_some_pages(vcpu);
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r = __direct_map(vcpu, v, write, level, gfn, pfn);
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r = __direct_map(vcpu, v, write, map_writable, level, gfn, pfn);
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spin_unlock(&vcpu->kvm->mmu_lock);
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@ -2611,11 +2616,11 @@ static bool can_do_async_pf(struct kvm_vcpu *vcpu)
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}
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static bool try_async_pf(struct kvm_vcpu *vcpu, bool no_apf, gfn_t gfn,
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gva_t gva, pfn_t *pfn)
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gva_t gva, pfn_t *pfn, bool write, bool *writable)
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{
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bool async;
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*pfn = gfn_to_pfn_async(vcpu->kvm, gfn, &async);
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*pfn = gfn_to_pfn_async(vcpu->kvm, gfn, &async, write, writable);
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if (!async)
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return false; /* *pfn has correct page already */
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@ -2632,7 +2637,7 @@ static bool try_async_pf(struct kvm_vcpu *vcpu, bool no_apf, gfn_t gfn,
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return true;
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}
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*pfn = gfn_to_pfn(vcpu->kvm, gfn);
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*pfn = gfn_to_pfn_prot(vcpu->kvm, gfn, write, writable);
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return false;
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}
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@ -2645,6 +2650,8 @@ static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa, u32 error_code,
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int level;
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gfn_t gfn = gpa >> PAGE_SHIFT;
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unsigned long mmu_seq;
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int write = error_code & PFERR_WRITE_MASK;
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bool map_writable;
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ASSERT(vcpu);
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ASSERT(VALID_PAGE(vcpu->arch.mmu.root_hpa));
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@ -2660,7 +2667,7 @@ static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa, u32 error_code,
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mmu_seq = vcpu->kvm->mmu_notifier_seq;
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smp_rmb();
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if (try_async_pf(vcpu, no_apf, gfn, gpa, &pfn))
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if (try_async_pf(vcpu, no_apf, gfn, gpa, &pfn, write, &map_writable))
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return 0;
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/* mmio */
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@ -2670,7 +2677,7 @@ static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa, u32 error_code,
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if (mmu_notifier_retry(vcpu, mmu_seq))
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goto out_unlock;
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kvm_mmu_free_some_pages(vcpu);
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r = __direct_map(vcpu, gpa, error_code & PFERR_WRITE_MASK,
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r = __direct_map(vcpu, gpa, write, map_writable,
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level, gfn, pfn);
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spin_unlock(&vcpu->kvm->mmu_lock);
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@ -427,7 +427,7 @@ static void FNAME(pte_prefetch)(struct kvm_vcpu *vcpu, struct guest_walker *gw,
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static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
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struct guest_walker *gw,
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int user_fault, int write_fault, int hlevel,
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int *ptwrite, pfn_t pfn)
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int *ptwrite, pfn_t pfn, bool map_writable)
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{
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unsigned access = gw->pt_access;
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struct kvm_mmu_page *sp = NULL;
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@ -501,7 +501,7 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
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mmu_set_spte(vcpu, it.sptep, access, gw->pte_access & access,
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user_fault, write_fault, dirty, ptwrite, it.level,
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gw->gfn, pfn, false, true);
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gw->gfn, pfn, false, map_writable);
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FNAME(pte_prefetch)(vcpu, gw, it.sptep);
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return it.sptep;
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@ -539,6 +539,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, u32 error_code,
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pfn_t pfn;
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int level = PT_PAGE_TABLE_LEVEL;
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unsigned long mmu_seq;
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bool map_writable;
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pgprintk("%s: addr %lx err %x\n", __func__, addr, error_code);
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@ -569,13 +570,17 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, u32 error_code,
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mmu_seq = vcpu->kvm->mmu_notifier_seq;
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smp_rmb();
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if (try_async_pf(vcpu, no_apf, walker.gfn, addr, &pfn))
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if (try_async_pf(vcpu, no_apf, walker.gfn, addr, &pfn, write_fault,
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&map_writable))
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return 0;
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/* mmio */
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if (is_error_pfn(pfn))
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return kvm_handle_bad_page(vcpu->kvm, walker.gfn, pfn);
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if (!map_writable)
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walker.pte_access &= ~ACC_WRITE_MASK;
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spin_lock(&vcpu->kvm->mmu_lock);
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if (mmu_notifier_retry(vcpu, mmu_seq))
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goto out_unlock;
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@ -583,7 +588,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, u32 error_code,
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trace_kvm_mmu_audit(vcpu, AUDIT_PRE_PAGE_FAULT);
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kvm_mmu_free_some_pages(vcpu);
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sptep = FNAME(fetch)(vcpu, addr, &walker, user_fault, write_fault,
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level, &write_pt, pfn);
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level, &write_pt, pfn, map_writable);
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(void)sptep;
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pgprintk("%s: shadow pte %p %llx ptwrite %d\n", __func__,
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sptep, *sptep, write_pt);
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@ -334,8 +334,11 @@ void kvm_set_page_accessed(struct page *page);
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pfn_t hva_to_pfn_atomic(struct kvm *kvm, unsigned long addr);
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pfn_t gfn_to_pfn_atomic(struct kvm *kvm, gfn_t gfn);
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pfn_t gfn_to_pfn_async(struct kvm *kvm, gfn_t gfn, bool *async);
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pfn_t gfn_to_pfn_async(struct kvm *kvm, gfn_t gfn, bool *async,
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bool write_fault, bool *writable);
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pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn);
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pfn_t gfn_to_pfn_prot(struct kvm *kvm, gfn_t gfn, bool write_fault,
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bool *writable);
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pfn_t gfn_to_pfn_memslot(struct kvm *kvm,
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struct kvm_memory_slot *slot, gfn_t gfn);
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int memslot_id(struct kvm *kvm, gfn_t gfn);
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@ -959,7 +959,7 @@ static pfn_t get_fault_pfn(void)
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}
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static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr, bool atomic,
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bool *async)
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bool *async, bool write_fault, bool *writable)
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{
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struct page *page[1];
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int npages = 0;
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@ -968,12 +968,34 @@ static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr, bool atomic,
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/* we can do it either atomically or asynchronously, not both */
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BUG_ON(atomic && async);
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BUG_ON(!write_fault && !writable);
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if (writable)
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*writable = true;
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if (atomic || async)
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npages = __get_user_pages_fast(addr, 1, 1, page);
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if (unlikely(npages != 1) && !atomic) {
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might_sleep();
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npages = get_user_pages_fast(addr, 1, 1, page);
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if (writable)
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*writable = write_fault;
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npages = get_user_pages_fast(addr, 1, write_fault, page);
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/* map read fault as writable if possible */
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if (unlikely(!write_fault) && npages == 1) {
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struct page *wpage[1];
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npages = __get_user_pages_fast(addr, 1, 1, wpage);
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if (npages == 1) {
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*writable = true;
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put_page(page[0]);
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page[0] = wpage[0];
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}
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npages = 1;
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}
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}
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if (unlikely(npages != 1)) {
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@ -1011,11 +1033,12 @@ static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr, bool atomic,
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pfn_t hva_to_pfn_atomic(struct kvm *kvm, unsigned long addr)
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{
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return hva_to_pfn(kvm, addr, true, NULL);
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return hva_to_pfn(kvm, addr, true, NULL, true, NULL);
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}
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EXPORT_SYMBOL_GPL(hva_to_pfn_atomic);
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static pfn_t __gfn_to_pfn(struct kvm *kvm, gfn_t gfn, bool atomic, bool *async)
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static pfn_t __gfn_to_pfn(struct kvm *kvm, gfn_t gfn, bool atomic, bool *async,
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bool write_fault, bool *writable)
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{
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unsigned long addr;
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@ -1028,32 +1051,40 @@ static pfn_t __gfn_to_pfn(struct kvm *kvm, gfn_t gfn, bool atomic, bool *async)
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return page_to_pfn(bad_page);
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}
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return hva_to_pfn(kvm, addr, atomic, async);
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return hva_to_pfn(kvm, addr, atomic, async, write_fault, writable);
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}
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pfn_t gfn_to_pfn_atomic(struct kvm *kvm, gfn_t gfn)
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{
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return __gfn_to_pfn(kvm, gfn, true, NULL);
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return __gfn_to_pfn(kvm, gfn, true, NULL, true, NULL);
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}
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EXPORT_SYMBOL_GPL(gfn_to_pfn_atomic);
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pfn_t gfn_to_pfn_async(struct kvm *kvm, gfn_t gfn, bool *async)
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pfn_t gfn_to_pfn_async(struct kvm *kvm, gfn_t gfn, bool *async,
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bool write_fault, bool *writable)
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{
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return __gfn_to_pfn(kvm, gfn, false, async);
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return __gfn_to_pfn(kvm, gfn, false, async, write_fault, writable);
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}
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EXPORT_SYMBOL_GPL(gfn_to_pfn_async);
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pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn)
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{
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return __gfn_to_pfn(kvm, gfn, false, NULL);
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return __gfn_to_pfn(kvm, gfn, false, NULL, true, NULL);
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}
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EXPORT_SYMBOL_GPL(gfn_to_pfn);
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pfn_t gfn_to_pfn_prot(struct kvm *kvm, gfn_t gfn, bool write_fault,
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bool *writable)
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{
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return __gfn_to_pfn(kvm, gfn, false, NULL, write_fault, writable);
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}
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EXPORT_SYMBOL_GPL(gfn_to_pfn_prot);
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pfn_t gfn_to_pfn_memslot(struct kvm *kvm,
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struct kvm_memory_slot *slot, gfn_t gfn)
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{
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unsigned long addr = gfn_to_hva_memslot(slot, gfn);
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return hva_to_pfn(kvm, addr, false, NULL);
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return hva_to_pfn(kvm, addr, false, NULL, true, NULL);
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}
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int gfn_to_page_many_atomic(struct kvm *kvm, gfn_t gfn, struct page **pages,
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