KVM: Implement helper functions for setting x86 control registers

Link: https://lore.kernel.org/ltp/[email protected]/
Reviewed-by: Petr Vorel <[email protected]>
Signed-off-by: Martin Doucha <[email protected]>

Author: mdoucha

testcases/kernel/kvm/include/kvm_x86.h

@@ -221,6 +221,9 @@ unsigned int kvm_create_stack_descriptor(struct segment_descriptor *table,
 void kvm_get_cpuid(unsigned int eax, unsigned int ecx, struct kvm_cpuid *buf);
 void kvm_read_cregs(struct kvm_cregs *buf);
 void kvm_read_sregs(struct kvm_sregs *buf);
+void kvm_set_cr0(unsigned long val);
+void kvm_set_cr3(unsigned long val);
+void kvm_set_cr4(unsigned long val);
 uint64_t kvm_rdmsr(unsigned int msr);
 void kvm_wrmsr(unsigned int msr, uint64_t value);
 

testcases/kernel/kvm/lib_x86.c

@@ -214,6 +214,33 @@ void kvm_get_cpuid(unsigned int eax, unsigned int ecx, struct kvm_cpuid *buf)
 	);
 }
 
+void kvm_set_cr0(unsigned long val)
+{
+	asm (
+		"mov %0, %%cr0\n"
+		:
+		: "r" (val)
+	);
+}
+
+void kvm_set_cr3(unsigned long val)
+{
+	asm (
+		"mov %0, %%cr3\n"
+		:
+		: "r" (val)
+	);
+}
+
+void kvm_set_cr4(unsigned long val)
+{
+	asm (
+		"mov %0, %%cr4\n"
+		:
+		: "r" (val)
+	);
+}
+
 uint64_t kvm_rdmsr(unsigned int msr)
 {
 	unsigned int ret_lo, ret_hi;