#define nop() asm volatile ("nop")
+static inline void serialize(void)
+{
+ /* Instruction opcode for SERIALIZE; supported in binutils >= 2.35. */
+ asm volatile(".byte 0xf, 0x1, 0xe8" ::: "memory");
+}
+
+ /* The dst parameter must be 64-bytes aligned */
+ static inline void movdir64b(void *dst, const void *src)
+ {
+ const struct { char _[64]; } *__src = src;
+ struct { char _[64]; } *__dst = dst;
+
+ /*
+ * MOVDIR64B %(rdx), rax.
+ *
+ * Both __src and __dst must be memory constraints in order to tell the
+ * compiler that no other memory accesses should be reordered around
+ * this one.
+ *
+ * Also, both must be supplied as lvalues because this tells
+ * the compiler what the object is (its size) the instruction accesses.
+ * I.e., not the pointers but what they point to, thus the deref'ing '*'.
+ */
+ asm volatile(".byte 0x66, 0x0f, 0x38, 0xf8, 0x02"
+ : "+m" (*__dst)
+ : "m" (*__src), "a" (__dst), "d" (__src));
+ }
+
+ /**
+ * enqcmds - Enqueue a command in supervisor (CPL0) mode
+ * @dst: destination, in MMIO space (must be 512-bit aligned)
+ * @src: 512 bits memory operand
+ *
+ * The ENQCMDS instruction allows software to write a 512-bit command to
+ * a 512-bit-aligned special MMIO region that supports the instruction.
+ * A return status is loaded into the ZF flag in the RFLAGS register.
+ * ZF = 0 equates to success, and ZF = 1 indicates retry or error.
+ *
+ * This function issues the ENQCMDS instruction to submit data from
+ * kernel space to MMIO space, in a unit of 512 bits. Order of data access
+ * is not guaranteed, nor is a memory barrier performed afterwards. It
+ * returns 0 on success and -EAGAIN on failure.
+ *
+ * Warning: Do not use this helper unless your driver has checked that the
+ * ENQCMDS instruction is supported on the platform and the device accepts
+ * ENQCMDS.
+ */
+ static inline int enqcmds(void __iomem *dst, const void *src)
+ {
+ const struct { char _[64]; } *__src = src;
+ struct { char _[64]; } *__dst = dst;
+ int zf;
+
+ /*
+ * ENQCMDS %(rdx), rax
+ *
+ * See movdir64b()'s comment on operand specification.
+ */
+ asm volatile(".byte 0xf3, 0x0f, 0x38, 0xf8, 0x02, 0x66, 0x90"
+ CC_SET(z)
+ : CC_OUT(z) (zf), "+m" (*__dst)
+ : "m" (*__src), "a" (__dst), "d" (__src));
+
+ /* Submission failure is indicated via EFLAGS.ZF=1 */
+ if (zf)
+ return -EAGAIN;
+
+ return 0;
+ }
+
#endif /* __KERNEL__ */
#endif /* _ASM_X86_SPECIAL_INSNS_H */