[RFC 4/4] nvme-pci: add quirk for qemu with bogus NOWS

[Luis Chamberlain <mcgrof@kernel.org>]

The NOWS value for qemu is bogus but that means we need
to be mucking with userspace when testing large IO, so just
add a quirk to use sensible max limits, in this case just use
MDTS as these drives are virtualized.

Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
---
 drivers/nvme/host/core.c | 2 ++
 drivers/nvme/host/nvme.h | 5 +++++
 drivers/nvme/host/pci.c  | 3 ++-
 3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index f028913e2e62..8f516de16281 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2070,6 +2070,8 @@ static bool nvme_update_disk_info(struct nvme_ns *ns, struct nvme_id_ns *id,
 		/* NOWS = Namespace Optimal Write Size */
 		if (id->nows)
 			io_opt = bs * (1 + le16_to_cpu(id->nows));
+		else if (ns->ctrl->quirks & NVME_QUIRK_BOGUS_NOWS)
+			io_opt = lim->max_hw_sectors << SECTOR_SHIFT;
 	}
 
 	/*
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 7be92d07430e..c63a804db462 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),
+
+	/*
+	 * Reports a NOWS of 0 which is 1 logical block size which is bogus
+	 */
+	NVME_QUIRK_BOGUS_NOWS			= (1 << 23),
 };
 
 /*
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 27b830072c14..577d8f909139 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -3469,7 +3469,8 @@ static const struct pci_device_id nvme_id_table[] = {
 				NVME_QUIRK_DISABLE_WRITE_ZEROES |
 				NVME_QUIRK_BOGUS_NID, },
 	{ PCI_VDEVICE(REDHAT, 0x0010),	/* Qemu emulated controller */
-		.driver_data = NVME_QUIRK_BOGUS_NID, },
+		.driver_data = NVME_QUIRK_BOGUS_NID |
+				NVME_QUIRK_BOGUS_NOWS, },
 	{ PCI_DEVICE(0x1217, 0x8760), /* O2 Micro 64GB Steam Deck */
 		.driver_data = NVME_QUIRK_DMAPOOL_ALIGN_512, },
 	{ PCI_DEVICE(0x126f, 0x2262),	/* Silicon Motion generic */
-- 
2.47.2