KVM: Allow cross page reads and writes from cached translations.

This patch adds support for kvm_gfn_to_hva_cache_init functions for
reads and writes that will cross a page.  If the range falls within
the same memslot, then this will be a fast operation.  If the range
is split between two memslots, then the slower kvm_read_guest and
kvm_write_guest are used.

Tested: Test against kvm_clock unit tests.

Signed-off-by: Andrew Honig <ahonig@google.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>

2 files changed, 7 insertions, 8 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;