5 files changed, 46 insertions, 19 deletions

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 02b51dd4e4ad..f77df1c5de6e 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1857,7 +1857,7 @@ int kvm_lapic_enable_pv_eoi(struct kvm_vcpu *vcpu, u64 data)
         if (!pv_eoi_enabled(vcpu))
                 return 0;
         return kvm_gfn_to_hva_cache_init(vcpu->kvm, &vcpu->arch.pv_eoi.data,
-                                         addr);
+                                         addr, sizeof(u8));
 }
 
 void kvm_lapic_init(void)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index f19ac0aca60d..e1721324c271 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1823,7 +1823,8 @@ static int kvm_pv_enable_async_pf(struct kvm_vcpu *vcpu, u64 data)
                 return 0;
         }
 
-        if (kvm_gfn_to_hva_cache_init(vcpu->kvm, &vcpu->arch.apf.data, gpa))
+        if (kvm_gfn_to_hva_cache_init(vcpu->kvm, &vcpu->arch.apf.data, gpa,
+                                        sizeof(u32)))
                 return 1;
 
         vcpu->arch.apf.send_user_only = !(data & KVM_ASYNC_PF_SEND_ALWAYS);
@@ -1952,12 +1953,9 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 
                 gpa_offset = data & ~(PAGE_MASK | 1);
 
-                /* Check that the address is 32-byte aligned. */
-                if (gpa_offset & (sizeof(struct pvclock_vcpu_time_info) - 1))
-                        break;
-
                 if (kvm_gfn_to_hva_cache_init(vcpu->kvm,
-                     &vcpu->arch.pv_time, data & ~1ULL))
+                     &vcpu->arch.pv_time, data & ~1ULL,
+                     sizeof(struct pvclock_vcpu_time_info)))
                         vcpu->arch.pv_time_enabled = false;
                 else
                         vcpu->arch.pv_time_enabled = true;
@@ -1977,7 +1975,8 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
                         return 1;
 
                 if (kvm_gfn_to_hva_cache_init(vcpu->kvm, &vcpu->arch.st.stime,
-                                                        data & KVM_STEAL_VALID_BITS))
+                                                data & KVM_STEAL_VALID_BITS,
+                                                sizeof(struct kvm_steal_time)))
                         return 1;
 
                 vcpu->arch.st.msr_val = data;
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index cad77fe09d77..c13958251927 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -518,7 +518,7 @@ int kvm_write_guest(struct kvm *kvm, gpa_t gpa, const void *data,
 int kvm_write_guest_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
                            void *data, unsigned long len);
 int kvm_gfn_to_hva_cache_init(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
-                              gpa_t gpa);
+                              gpa_t gpa, unsigned long len);
 int kvm_clear_guest_page(struct kvm *kvm, gfn_t gfn, int offset, int len);
 int kvm_clear_guest(struct kvm *kvm, gpa_t gpa, unsigned long len);
 struct kvm_memory_slot *gfn_to_memslot(struct kvm *kvm, gfn_t gfn);
diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h
index fa7cc7244cbd..b0bcce0ddc95 100644
--- a/include/linux/kvm_types.h
+++ b/include/linux/kvm_types.h
@@ -71,6 +71,7 @@ struct gfn_to_hva_cache {
         u64 generation;
         gpa_t gpa;
         unsigned long hva;
+        unsigned long len;
         struct kvm_memory_slot *memslot;
 };
 
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index adc68feb5c5a..f18013f09e68 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1541,21 +1541,38 @@ int kvm_write_guest(struct kvm *kvm, gpa_t gpa, const void *data,
 }
 
 int kvm_gfn_to_hva_cache_init(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
-                              gpa_t gpa)
+                              gpa_t gpa, unsigned long len)
 {
         struct kvm_memslots *slots = kvm_memslots(kvm);
         int offset = offset_in_page(gpa);
-        gfn_t gfn = gpa >> PAGE_SHIFT;
+        gfn_t start_gfn = gpa >> PAGE_SHIFT;
+        gfn_t end_gfn = (gpa + len - 1) >> PAGE_SHIFT;
+        gfn_t nr_pages_needed = end_gfn - start_gfn + 1;
+        gfn_t nr_pages_avail;
 
         ghc->gpa = gpa;
         ghc->generation = slots->generation;
-        ghc->memslot = gfn_to_memslot(kvm, gfn);
-        ghc->hva = gfn_to_hva_many(ghc->memslot, gfn, NULL);
-        if (!kvm_is_error_hva(ghc->hva))
+        ghc->len = len;
+        ghc->memslot = gfn_to_memslot(kvm, start_gfn);
+        ghc->hva = gfn_to_hva_many(ghc->memslot, start_gfn, &nr_pages_avail);
+        if (!kvm_is_error_hva(ghc->hva) && nr_pages_avail >= nr_pages_needed) {
                 ghc->hva += offset;
-        else
-                return -EFAULT;
-
+        } else {
+                /*
+                 * If the requested region crosses two memslots, we still
+                 * verify that the entire region is valid here.
+                 */
+                while (start_gfn <= end_gfn) {
+                        ghc->memslot = gfn_to_memslot(kvm, start_gfn);
+                        ghc->hva = gfn_to_hva_many(ghc->memslot, start_gfn,
+                                                   &nr_pages_avail);
+                        if (kvm_is_error_hva(ghc->hva))
+                                return -EFAULT;
+                        start_gfn += nr_pages_avail;
+                }
+                /* Use the slow path for cross page reads and writes. */
+                ghc->memslot = NULL;
+        }
         return 0;
 }
 EXPORT_SYMBOL_GPL(kvm_gfn_to_hva_cache_init);
@@ -1566,8 +1583,13 @@ int kvm_write_guest_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
         struct kvm_memslots *slots = kvm_memslots(kvm);
         int r;
 
+        BUG_ON(len > ghc->len);
+
         if (slots->generation != ghc->generation)
-                kvm_gfn_to_hva_cache_init(kvm, ghc, ghc->gpa);
+                kvm_gfn_to_hva_cache_init(kvm, ghc, ghc->gpa, ghc->len);
+
+        if (unlikely(!ghc->memslot))
+                return kvm_write_guest(kvm, ghc->gpa, data, len);
 
         if (kvm_is_error_hva(ghc->hva))
                 return -EFAULT;
@@ -1587,8 +1609,13 @@ int kvm_read_guest_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
         struct kvm_memslots *slots = kvm_memslots(kvm);
         int r;
 
+        BUG_ON(len > ghc->len);
+
         if (slots->generation != ghc->generation)
-                kvm_gfn_to_hva_cache_init(kvm, ghc, ghc->gpa);
+                kvm_gfn_to_hva_cache_init(kvm, ghc, ghc->gpa, ghc->len);
+
+        if (unlikely(!ghc->memslot))
+                return kvm_read_guest(kvm, ghc->gpa, data, len);
 
         if (kvm_is_error_hva(ghc->hva))
                 return -EFAULT;