scsi: libsas: Align SMP request allocation to ARCH_DMA_MINALIGN

This series [1] reduced the kmalloc() minimum alignment on arm64 to 8 bytes
(from 128). In libsas, this will cause SMP requests to be 8-byte aligned
through kmalloc() allocation. However, for hisi_sas hardware, all command
addresses must be 16-byte-aligned. Otherwise, the commands fail to be
executed.

ARCH_DMA_MINALIGN represents the minimum (static) alignment for safe DMA
operations, so use ARCH_DMA_MINALIGN as the alignment for SMP request.

Link: https://lkml.kernel.org/r/[email protected] [1]
Signed-off-by: Yihang Li <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Damien Le Moal <[email protected]>
Reviewed-by: John Garry <[email protected]>
Reviewed-by: Jason Yan <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

Author: Yihang Li

drivers/scsi/libsas/sas_expander.c

@@ -135,7 +135,7 @@ static int smp_execute_task(struct domain_device *dev, void *req, int req_size,
 
 static inline void *alloc_smp_req(int size)
 {
-	u8 *p = kzalloc(size, GFP_KERNEL);
+	u8 *p = kzalloc(ALIGN(size, ARCH_DMA_MINALIGN), GFP_KERNEL);
 	if (p)
 		p[0] = SMP_REQUEST;
 	return p;