[hyperv] Add support for Hyper-V hypervisor

Add support for detecting and communicating with the Hyper-V
hypervisor.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/arch/x86_64/include/bits/hyperv.h

@@ -0,0 +1,75 @@
+#ifndef _BITS_HYPERV_H
+#define _BITS_HYPERV_H
+
+/** @file
+ *
+ * Hyper-V interface
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <stddef.h>
+#include <stdint.h>
+#include <ipxe/io.h>
+
+/**
+ * Issue hypercall
+ *
+ * @v hv		Hyper-V hypervisor
+ * @v code		Call code
+ * @v in		Input parameters
+ * @v out		Output parameters
+ * @ret status		Status code
+ */
+static inline __attribute__ (( always_inline )) int
+hv_call ( struct hv_hypervisor *hv, unsigned int code, const void *in,
+	  void *out ) {
+	void *hypercall = hv->hypercall;
+	register uint64_t rcx asm ( "rcx" );
+	register uint64_t rdx asm ( "rdx" );
+	register uint64_t r8 asm ( "r8" );
+	uint64_t in_phys;
+	uint64_t out_phys;
+	uint16_t result;
+
+	in_phys = ( ( __builtin_constant_p ( in ) && ( in == NULL ) )
+		       ? 0 : virt_to_phys ( in ) );
+	out_phys = ( ( __builtin_constant_p ( out ) && ( out == NULL ) )
+		       ? 0 : virt_to_phys ( out ) );
+	rcx = code;
+	rdx = in_phys;
+	r8 = out_phys;
+	__asm__ __volatile__ ( "call *%4"
+			       : "=a" ( result ), "+r" ( rcx ), "+r" ( rdx ),
+				 "+r" ( r8 )
+			       : "m" ( hypercall )
+			       : "r9", "r10", "r11", "xmm0", "xmm1", "xmm2",
+				 "xmm3", "xmm4", "xmm5" );
+	return result;
+}
+
+/**
+ * Set bit atomically
+ *
+ * @v bits		Bit field
+ * @v bit		Bit to set
+ */
+static inline __attribute__ (( always_inline )) void
+hv_set_bit ( void *bits, unsigned int bit ) {
+	struct {
+		uint64_t qword[ ( bit / 64 ) + 1 ];
+	} *qwords = bits;
+
+	/* Set bit using "lock bts".  Inform compiler that any memory
+	 * from the start of the bit field up to and including the
+	 * qword containing this bit may be modified.  (This is
+	 * overkill but shouldn't matter in practice since we're
+	 * unlikely to subsequently read other bits from the same bit
+	 * field.)
+	 */
+	__asm__ __volatile__ ( "lock bts %1, %0"
+			       : "+m" ( *qwords ) : "Ir" ( bit ) );
+}
+
+#endif /* _BITS_HYPERV_H */