KVM: Provide unlocked version of emulator_write_phys()

Signed-off-by: Avi Kivity <avi@qumranet.com>

arch/x86/kvm/x86.c

@@ -1840,22 +1840,29 @@ mmio:
 	return X86EMUL_UNHANDLEABLE;
 }
 
-static int emulator_write_phys(struct kvm_vcpu *vcpu, gpa_t gpa,
+int __emulator_write_phys(struct kvm_vcpu *vcpu, gpa_t gpa,
 			  const void *val, int bytes)
 {
 	int ret;
 
-	down_read(&vcpu->kvm->slots_lock);
 	ret = kvm_write_guest(vcpu->kvm, gpa, val, bytes);
-	if (ret < 0) {
-		up_read(&vcpu->kvm->slots_lock);
+	if (ret < 0)
 		return 0;
-	}
 	kvm_mmu_pte_write(vcpu, gpa, val, bytes);
-	up_read(&vcpu->kvm->slots_lock);
 	return 1;
 }
 
+static int emulator_write_phys(struct kvm_vcpu *vcpu, gpa_t gpa,
+			const void *val, int bytes)
+{
+	int ret;
+
+	down_read(&vcpu->kvm->slots_lock);
+	ret =__emulator_write_phys(vcpu, gpa, val, bytes);
+	up_read(&vcpu->kvm->slots_lock);
+	return ret;
+}
+
 static int emulator_write_emulated_onepage(unsigned long addr,
 					   const void *val,
 					   unsigned int bytes,

include/asm-x86/kvm_host.h

@@ -432,6 +432,9 @@ void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned int kvm_nr_mmu_pages);
 
 int load_pdptrs(struct kvm_vcpu *vcpu, unsigned long cr3);
 
+int __emulator_write_phys(struct kvm_vcpu *vcpu, gpa_t gpa,
+			  const void *val, int bytes);
+
 enum emulation_result {
 	EMULATE_DONE,       /* no further processing */
 	EMULATE_DO_MMIO,      /* kvm_run filled with mmio request */