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>

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,

arch/x86/kvm/x86.c

@@ -1976,9 +1976,7 @@ 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,
+int kvm_read_guest_virt(gva_t addr, void *val, unsigned int bytes,
 			struct kvm_vcpu *vcpu)
 {
 	void *data = val;
@@ -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,
@@ -2029,7 +2057,7 @@ 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)
+	if (kvm_read_guest_virt(addr, val, bytes, vcpu)
 				== X86EMUL_CONTINUE)
 		return X86EMUL_CONTINUE;
 	if (gpa == UNMAPPED_GVA)
@@ -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,