X86: uv: implement a gru_read_gpa kernel function

The BIOS has decided to store a pointer to the partition reserved page in
a scratch MMR. The GRU is only able to read an MMR using a vload
instruction. The gru_read_gpa() function will implemented.

Signed-off-by: Robin Holt <[e-mail]>
Signed-off-by: Jack Steiner <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/misc/sgi-gru/gru_instructions.h

···
  *     	- nelem and stride are in elements
  *     	- tri0/tri1 is in bytes for the beginning of the data segment.
  */
+static inline void gru_vload_phys(void *cb, unsigned long gpa,
+		unsigned int tri0, int iaa, unsigned long hints)
+{
+	struct gru_instruction *ins = (struct gru_instruction *)cb;
+
+	ins->baddr0 = (long)gpa | ((unsigned long)iaa << 62);
+	ins->nelem = 1;
+	ins->tri0 = tri0;
+	ins->op1_stride = 1;
+	gru_start_instruction(ins, __opword(OP_VLOAD, 0, XTYPE_DW, iaa, 0,
+					CB_IMA(hints)));
+}
+
 static inline void gru_vload(void *cb, unsigned long mem_addr,
 		unsigned int tri0, unsigned char xtype, unsigned long nelem,
 		unsigned long stride, unsigned long hints)

drivers/misc/sgi-gru/grukservices.c

···
 /* ---------------------- GRU DATA COPY FUNCTIONS ---------------------------*/
 
 /*
+ * Load a DW from a global GPA. The GPA can be a memory or MMR address.
+ */
+int gru_read_gpa(unsigned long *value, unsigned long gpa)
+{
+	void *cb;
+	void *dsr;
+	int ret, iaa;
+
+	STAT(read_gpa);
+	if (gru_get_cpu_resources(GRU_NUM_KERNEL_DSR_BYTES, &cb, &dsr))
+		return MQE_BUG_NO_RESOURCES;
+	iaa = gpa >> 62;
+	gru_vload_phys(cb, gpa, gru_get_tri(dsr), iaa, IMA);
+	ret = gru_wait(cb);
+	if (ret == CBS_IDLE)
+		*value = *(unsigned long *)dsr;
+	gru_free_cpu_resources(cb, dsr);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(gru_read_gpa);
+
+
+/*
  * Copy a block of data using the GRU resources
  */
 int gru_copy_gpa(unsigned long dest_gpa, unsigned long src_gpa,

drivers/misc/sgi-gru/grukservices.h

···
 
 
 /*
+ * Read a GRU global GPA. Source can be located in a remote partition.
+ *
+ *    Input:
+ *    	value		memory address where MMR value is returned
+ *    	gpa		source numalink physical address of GPA
+ *
+ *    Output:
+ *	0		OK
+ *	>0		error
+ */
+int gru_read_gpa(unsigned long *value, unsigned long gpa);
+
+
+/*
  * Copy data using the GRU. Source or destination can be located in a remote
  * partition.
  *

drivers/misc/sgi-gru/gruprocfs.c

···
 	printstat(s, flush_tlb_gru_tgh);
 	printstat(s, flush_tlb_gru_zero_asid);
 	printstat(s, copy_gpa);
+	printstat(s, read_gpa);
 	printstat(s, mesq_receive);
 	printstat(s, mesq_receive_none);
 	printstat(s, mesq_send);

drivers/misc/sgi-gru/grutables.h

···
 	atomic_long_t flush_tlb_gru_zero_asid;
 
 	atomic_long_t copy_gpa;
+	atomic_long_t read_gpa;
 
 	atomic_long_t mesq_receive;
 	atomic_long_t mesq_receive_none;