KVM: LoongArch: selftests: Add basic interfaces

Add some basic function interfaces such as CSR register access, local
irq enable or disable APIs.

Signed-off-by: Bibo Mao <[e-mail]>
Signed-off-by: Huacai Chen <[e-mail]>

tools/testing/selftests/kvm/include/loongarch/processor.h

···
 #define  CSR_TLBREHI_PS_SHIFT		0
 #define  CSR_TLBREHI_PS			(0x3fUL << CSR_TLBREHI_PS_SHIFT)
 
+#define csr_read(csr)				\
+({						\
+	register unsigned long __v;		\
+	__asm__ __volatile__(			\
+		"csrrd %[val], %[reg]\n\t"	\
+		: [val] "=r" (__v)		\
+		: [reg] "i" (csr)		\
+		: "memory");			\
+	__v;					\
+})
+
+#define csr_write(v, csr)			\
+({						\
+	register unsigned long __v = v;		\
+	__asm__ __volatile__ (			\
+		"csrwr %[val], %[reg]\n\t"	\
+		: [val] "+r" (__v)		\
+		: [reg] "i" (csr)		\
+		: "memory");			\
+	__v;					\
+})
+
 #define EXREGS_GPRS			(32)
 
 #ifndef __ASSEMBLER__
···
 #define PRMD_OFFSET_EXREGS		offsetof(struct ex_regs, prmd)
 #define EXREGS_SIZE			sizeof(struct ex_regs)
 
+static inline void cpu_relax(void)
+{
+	asm volatile("nop" ::: "memory");
+}
+
+static inline void local_irq_enable(void)
+{
+	unsigned int flags = CSR_CRMD_IE;
+	register unsigned int mask asm("$t0") = CSR_CRMD_IE;
+
+	__asm__ __volatile__(
+		"csrxchg %[val], %[mask], %[reg]\n\t"
+		: [val] "+r" (flags)
+		: [mask] "r" (mask), [reg] "i" (LOONGARCH_CSR_CRMD)
+		: "memory");
+}
+
+static inline void local_irq_disable(void)
+{
+	unsigned int flags = 0;
+	register unsigned int mask asm("$t0") = CSR_CRMD_IE;
+
+	__asm__ __volatile__(
+		"csrxchg %[val], %[mask], %[reg]\n\t"
+		: [val] "+r" (flags)
+		: [mask] "r" (mask), [reg] "i" (LOONGARCH_CSR_CRMD)
+		: "memory");
+}
 #else
 #define PC_OFFSET_EXREGS		((EXREGS_GPRS + 0) * 8)
 #define ESTAT_OFFSET_EXREGS		((EXREGS_GPRS + 1) * 8)

tools/testing/selftests/kvm/lib/loongarch/processor.c

···
 	while (1) ;
 }
 
+uint32_t guest_get_vcpuid(void)
+{
+	return csr_read(LOONGARCH_CSR_CPUID);
+}
+
 void vcpu_args_set(struct kvm_vcpu *vcpu, unsigned int num, ...)
 {
 	int i;