[PATCH 4/6] nvme: Add a quirk for page aligned admin queue buffers

Apple controllers seem to require any queue buffers on the admin queue
to be aligned to the NVMe controller page size. Weirdly, this constraint
does not apply to the i/o queue where any alignment is fine. This has
always been required on pre-M1 controllers and is required starting with
macOS 15 firmware or post-M4 controllers again. On M1/M2/M3 we only got
away with this because there was a chicken bit to disable this
requirement. Let's add a quirk that enforces this alignment.

Signed-off-by: Sven Peter <[email protected]>
---
 drivers/nvme/host/core.c | 5 ++++-
 drivers/nvme/host/nvme.h | 7 +++++++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 453c1f0b2dd0..b76f4e4d8850 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2071,7 +2071,10 @@ static void nvme_set_ctrl_limits(struct nvme_ctrl *ctrl,
 	lim->max_integrity_segments = ctrl->max_integrity_segments;
 	lim->virt_boundary_mask = ctrl->ops->get_virt_boundary(ctrl, is_admin);
 	lim->max_segment_size = UINT_MAX;
-	lim->dma_alignment = 3;
+	if (is_admin && (ctrl->quirks & NVME_QUIRK_ADMIN_PAGE_ALIGN))
+		lim->dma_alignment = NVME_CTRL_PAGE_SIZE - 1;
+	else
+		lim->dma_alignment = 3;
 }
 
 static bool nvme_update_disk_info(struct nvme_ns *ns, struct nvme_id_ns *id,
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 824651cc898d..957ded0c6f53 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -178,6 +178,11 @@ enum nvme_quirks {
 	 * Align dma pool segment size to 512 bytes
 	 */
 	NVME_QUIRK_DMAPOOL_ALIGN_512		= (1 << 22),
+
+	/*
+	 * Admin queue DMA buffers must be page aligned
+	 */
+	NVME_QUIRK_ADMIN_PAGE_ALIGN		= (1 << 23),
 };
 
 static inline char *nvme_quirk_name(enum nvme_quirks q)
@@ -229,6 +234,8 @@ static inline char *nvme_quirk_name(enum nvme_quirks q)
 		return "broken_msi";
 	case NVME_QUIRK_DMAPOOL_ALIGN_512:
 		return "dmapool_align_512";
+	case NVME_QUIRK_ADMIN_PAGE_ALIGN:
+		return "admin_page_align";
 	}
 
 	return "unknown";

-- 
2.55.0