iscsi_ibft: fix crash due to KASLR physical memory remapping

[linux-2.6-microblaze.git] / virt / kvm / kvm_main.c

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 6b4feb9..46fb042 100644 (file)
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -307,6 +307,7 @@ bool kvm_make_all_cpus_request(struct kvm *kvm, unsigned int req)
 {
        return kvm_make_all_cpus_request_except(kvm, req, NULL);
 }
+EXPORT_SYMBOL_GPL(kvm_make_all_cpus_request);
 
 #ifndef CONFIG_HAVE_KVM_ARCH_TLB_FLUSH_ALL
 void kvm_flush_remote_tlbs(struct kvm *kvm)
@@ -2054,6 +2055,13 @@ static bool vma_is_valid(struct vm_area_struct *vma, bool write_fault)
        return true;
 }
 
+static int kvm_try_get_pfn(kvm_pfn_t pfn)
+{
+       if (kvm_is_reserved_pfn(pfn))
+               return 1;
+       return get_page_unless_zero(pfn_to_page(pfn));
+}
+
 static int hva_to_pfn_remapped(struct vm_area_struct *vma,
                               unsigned long addr, bool *async,
                               bool write_fault, bool *writable,
@@ -2103,13 +2111,21 @@ static int hva_to_pfn_remapped(struct vm_area_struct *vma,
         * Whoever called remap_pfn_range is also going to call e.g.
         * unmap_mapping_range before the underlying pages are freed,
         * causing a call to our MMU notifier.
+        *
+        * Certain IO or PFNMAP mappings can be backed with valid
+        * struct pages, but be allocated without refcounting e.g.,
+        * tail pages of non-compound higher order allocations, which
+        * would then underflow the refcount when the caller does the
+        * required put_page. Don't allow those pages here.
         */ 
-       kvm_get_pfn(pfn);
+       if (!kvm_try_get_pfn(pfn))
+               r = -EFAULT;
 
 out:
        pte_unmap_unlock(ptep, ptl);
        *p_pfn = pfn;
-       return 0;
+
+       return r;
 }
 
 /*
@@ -2929,6 +2945,8 @@ static int kvm_vcpu_check_block(struct kvm_vcpu *vcpu)
                goto out;
        if (signal_pending(current))
                goto out;
+       if (kvm_check_request(KVM_REQ_UNBLOCK, vcpu))
+               goto out;
 
        ret = 0;
 out:
@@ -2973,8 +2991,7 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu)
                                goto out;
                        }
                        poll_end = cur = ktime_get();
-               } while (single_task_running() && !need_resched() &&
-                        ktime_before(cur, stop));
+               } while (kvm_vcpu_can_poll(cur, stop));
        }
 
        prepare_to_rcuwait(&vcpu->wait);