KVM: PPC: Avoid patching paravirt template code

Currently we patch the whole code include paravirt template code.
This isn't safe for scratch area and has impact to performance.

Signed-off-by: Liu Yu <yu.liu@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>

arch/powerpc/kernel/kvm.c

@@ -665,6 +665,9 @@ static void kvm_check_ins(u32 *inst, u32 features)
 	}
 }
 
+extern u32 kvm_template_start[];
+extern u32 kvm_template_end[];
+
 static void kvm_use_magic_page(void)
 {
 	u32 *p;
@@ -692,8 +695,14 @@ static void kvm_use_magic_page(void)
 	 */
 	local_irq_disable();
 
-	for (p = start; p < end; p++)
+	for (p = start; p < end; p++) {
+		/* Avoid patching the template code */
+		if (p >= kvm_template_start && p < kvm_template_end) {
+			p = kvm_template_end - 1;
+			continue;
+		}
 		kvm_check_ins(p, features);
+	}
 
 	local_irq_enable();
 

arch/powerpc/kernel/kvm_emul.S

@@ -66,6 +66,9 @@ kvm_hypercall_start:
 	   shared->critical == r1 and r2 is always != r1 */		\
 	STL64(r2, KVM_MAGIC_PAGE + KVM_MAGIC_CRITICAL, 0);
 
+.global kvm_template_start
+kvm_template_start:
+
 .global kvm_emulate_mtmsrd
 kvm_emulate_mtmsrd:
 
@@ -350,3 +353,6 @@ kvm_emulate_mtsrin_orig_ins_offs:
 .global kvm_emulate_mtsrin_len
 kvm_emulate_mtsrin_len:
 	.long (kvm_emulate_mtsrin_end - kvm_emulate_mtsrin) / 4
+
+.global kvm_template_end
+kvm_template_end: