KVM: introduce kvm_read_guest_virt, kvm_write_guest_virt

This commit change the name of emulator_read_std into kvm_read_guest_virt,
and add new function name kvm_write_guest_virt that allow writing into a
guest virtual address.

Signed-off-by: Izik Eidus <ieidus@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

2 files changed, 42 insertions, 18 deletions

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 9efc446b5ac6..b74576aec19a 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -609,10 +609,6 @@ void kvm_inject_nmi(struct kvm_vcpu *vcpu);
 
 void fx_init(struct kvm_vcpu *vcpu);
 
-int emulator_read_std(unsigned long addr,
-                      void *val,
-                      unsigned int bytes,
-                      struct kvm_vcpu *vcpu);
 int emulator_write_emulated(unsigned long addr,
                             const void *val,
                             unsigned int bytes,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 3b2acfd72d7f..67f91764e99b 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1976,10 +1976,8 @@ static struct kvm_io_device *vcpu_find_mmio_dev(struct kvm_vcpu *vcpu,
         return dev;
 }
 
-int emulator_read_std(unsigned long addr,
-                             void *val,
-                             unsigned int bytes,
-                             struct kvm_vcpu *vcpu)
+int kvm_read_guest_virt(gva_t addr, void *val, unsigned int bytes,
+                        struct kvm_vcpu *vcpu)
 {
         void *data = val;
         int r = X86EMUL_CONTINUE;
@@ -1987,27 +1985,57 @@ int emulator_read_std(unsigned long addr,
         while (bytes) {
                 gpa_t gpa = vcpu->arch.mmu.gva_to_gpa(vcpu, addr);
                 unsigned offset = addr & (PAGE_SIZE-1);
-                unsigned tocopy = min(bytes, (unsigned)PAGE_SIZE - offset);
+                unsigned toread = min(bytes, (unsigned)PAGE_SIZE - offset);
                 int ret;
 
                 if (gpa == UNMAPPED_GVA) {
                         r = X86EMUL_PROPAGATE_FAULT;
                         goto out;
                 }
-                ret = kvm_read_guest(vcpu->kvm, gpa, data, tocopy);
+                ret = kvm_read_guest(vcpu->kvm, gpa, data, toread);
                 if (ret < 0) {
                         r = X86EMUL_UNHANDLEABLE;
                         goto out;
                 }
 
-                bytes -= tocopy;
-                data += tocopy;
-                addr += tocopy;
+                bytes -= toread;
+                data += toread;
+                addr += toread;
         }
 out:
         return r;
 }
-EXPORT_SYMBOL_GPL(emulator_read_std);
+
+int kvm_write_guest_virt(gva_t addr, void *val, unsigned int bytes,
+                         struct kvm_vcpu *vcpu)
+{
+        void *data = val;
+        int r = X86EMUL_CONTINUE;
+
+        while (bytes) {
+                gpa_t gpa = vcpu->arch.mmu.gva_to_gpa(vcpu, addr);
+                unsigned offset = addr & (PAGE_SIZE-1);
+                unsigned towrite = min(bytes, (unsigned)PAGE_SIZE - offset);
+                int ret;
+
+                if (gpa == UNMAPPED_GVA) {
+                        r = X86EMUL_PROPAGATE_FAULT;
+                        goto out;
+                }
+                ret = kvm_write_guest(vcpu->kvm, gpa, data, towrite);
+                if (ret < 0) {
+                        r = X86EMUL_UNHANDLEABLE;
+                        goto out;
+                }
+
+                bytes -= towrite;
+                data += towrite;
+                addr += towrite;
+        }
+out:
+        return r;
+}
+
 
 static int emulator_read_emulated(unsigned long addr,
                                   void *val,
@@ -2029,8 +2057,8 @@ static int emulator_read_emulated(unsigned long addr,
         if ((gpa & PAGE_MASK) == APIC_DEFAULT_PHYS_BASE)
                 goto mmio;
 
-        if (emulator_read_std(addr, val, bytes, vcpu)
-                        == X86EMUL_CONTINUE)
+        if (kvm_read_guest_virt(addr, val, bytes, vcpu)
+                                == X86EMUL_CONTINUE)
                 return X86EMUL_CONTINUE;
         if (gpa == UNMAPPED_GVA)
                 return X86EMUL_PROPAGATE_FAULT;
@@ -2233,7 +2261,7 @@ void kvm_report_emulation_failure(struct kvm_vcpu *vcpu, const char *context)
 
         rip_linear = rip + get_segment_base(vcpu, VCPU_SREG_CS);
 
-        emulator_read_std(rip_linear, (void *)opcodes, 4, vcpu);
+        kvm_read_guest_virt(rip_linear, (void *)opcodes, 4, vcpu);
 
         printk(KERN_ERR "emulation failed (%s) rip %lx %02x %02x %02x %02x\n",
                context, rip, opcodes[0], opcodes[1], opcodes[2], opcodes[3]);
@@ -2241,7 +2269,7 @@ void kvm_report_emulation_failure(struct kvm_vcpu *vcpu, const char *context)
 EXPORT_SYMBOL_GPL(kvm_report_emulation_failure);
 
 static struct x86_emulate_ops emulate_ops = {
-        .read_std            = emulator_read_std,
+        .read_std            = kvm_read_guest_virt,
         .read_emulated       = emulator_read_emulated,
         .write_emulated      = emulator_write_emulated,
         .cmpxchg_emulated    = emulator_cmpxchg_emulated,