[PATCH 6.12.y 2/3] vhost-scsi: Allocate T10 PI structs only when enabled

[Sasha Levin <sashal@kernel.org>]

From: Mike Christie <michael.christie@oracle.com>

[ Upstream commit bf2d650391be508dd8b5e188b65ed32300cf3489 ]

T10 PI is not a widely used feature. This has us only allocate the
structs for it if the feature has been enabled. For a common small setup
where you have 1 virtqueue and 128 commands per queue, this saves:

8MB = 32 bytes per sg * 2048 entries * 128 commands

per vhost-scsi device.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20241203191705.19431-3-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Stable-dep-of: 01c3a5fa6d64 ("vhost-scsi: zero misaligned I/O bounce pages")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/vhost/scsi.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index 725166d4cc79f..4e1b5184cf36b 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -1712,12 +1712,14 @@ static int vhost_scsi_setup_vq_cmds(struct vhost_virtqueue *vq, int max_cmds)
 			goto out;
 		}
 
-		tv_cmd->tvc_prot_sgl = kcalloc(VHOST_SCSI_PREALLOC_PROT_SGLS,
-					       sizeof(struct scatterlist),
-					       GFP_KERNEL);
-		if (!tv_cmd->tvc_prot_sgl) {
-			pr_err("Unable to allocate tv_cmd->tvc_prot_sgl\n");
-			goto out;
+		if (vhost_has_feature(vq, VIRTIO_SCSI_F_T10_PI)) {
+			tv_cmd->tvc_prot_sgl = kcalloc(VHOST_SCSI_PREALLOC_PROT_SGLS,
+						sizeof(struct scatterlist),
+						GFP_KERNEL);
+			if (!tv_cmd->tvc_prot_sgl) {
+				pr_err("Unable to allocate tv_cmd->tvc_prot_sgl\n");
+				goto out;
+			}
 		}
 	}
 	return 0;
-- 
2.53.0