On 10/8/25 17:39, Andre Przywara wrote:
On Sat, 30 Aug 2025 22:39:54 +0200
Heinrich Schuchardt <[email protected]> wrote:
Hi Heinrich,
QEMU allows to specify the logical block size via parameter
logical_block_size of a virtio-blk-device.
The communication channel via virtqueues remains based on 512 byte blocks
even if the logical_block_size is larger.
Consider the logical block size in the block device driver.
Reported-by: Emil Renner Berthing <[email protected]>
Signed-off-by: Heinrich Schuchardt <[email protected]>
---
v2:
remove superfluous include linux/err.h
---
drivers/virtio/virtio_blk.c | 25 ++++++++++++++++++++++---
1 file changed, 22 insertions(+), 3 deletions(-)
diff --git a/drivers/virtio/virtio_blk.c b/drivers/virtio/virtio_blk.c
index 2f999fc8bbe..4224e3c17f4 100644
--- a/drivers/virtio/virtio_blk.c
+++ b/drivers/virtio/virtio_blk.c
@@ -12,10 +12,17 @@
#include <virtio_types.h>
#include <virtio.h>
#include <virtio_ring.h>
+#include <linux/log2.h>
#include "virtio_blk.h"
+/**
+ * struct virtio_blk_priv - private date for virtio block device
+ */
struct virtio_blk_priv {
+ /** @virtqueue - virtqueue to process */
struct virtqueue *vq;
+ /** @blksz_shift - log2 of block size divided by 512 */
+ u32 blksz_shift;
};
static const u32 feature[] = {
@@ -71,6 +78,8 @@ static ulong virtio_blk_do_req(struct udevice *dev, u64
sector,
u8 status;
int ret;
+ sector <<= priv->blksz_shift;
+ blkcnt <<= priv->blksz_shift;
virtio_blk_init_header_sg(dev, sector, type, &out_hdr, &hdr_sg);
sgs[num_out++] = &hdr_sg;
@@ -109,7 +118,7 @@ static ulong virtio_blk_do_req(struct udevice *dev, u64 sector,
;
log_debug("done\n");
- return status == VIRTIO_BLK_S_OK ? blkcnt : -EIO;
+ return status == VIRTIO_BLK_S_OK ? blkcnt >> priv->blksz_shift : -EIO;
}
static ulong virtio_blk_read(struct udevice *dev, lbaint_t start,
@@ -177,15 +186,25 @@ static int virtio_blk_probe(struct udevice *dev)
struct blk_desc *desc = dev_get_uclass_plat(dev);
u64 cap;
int ret;
+ u32 blk_size;
ret = virtio_find_vqs(dev, 1, &priv->vq);
if (ret)
return ret;
- desc->blksz = 512;
- desc->log2blksz = 9;
virtio_cread(dev, struct virtio_blk_config, capacity, &cap);
desc->lba = cap;
+ if (!virtio_has_feature(dev, VIRTIO_BLK_F_BLK_SIZE)) {
Is that actually the right condition check? I would assume that we only
query the blk_size field if the feature bit is *set*, not when it's
cleared?
We see a failure (virtio block device not registering), because blk_size is
0 on the Arm FVP fast model, which is fine I think because the feature bit
is clear as well.
Cheers,
Andre
Hello Andre,
Thanks for sharing your test results.
Looking at these QEMU lines, I think the evaluated feature flag is correct:
pc-bios/s390-ccw/virtio.h:163:
uint32_t blk_size; /* block size of device (if VIRTIO_BLK_F_BLK_SIZE) */
include/standard-headers/linux/virtio_blk.h:72-73:
/* block size of device (if VIRTIO_BLK_F_BLK_SIZE) */
__virtio32 blk_size;
virtio_has_feature() cannot detect a feature if is not in the feature
set of the U-Boot driver. See function virtio_uclass_child_pre_probe():
uc_priv->features = driver_features_legacy & device_features;
VIRTIO_BLK_F_BLK_SIZE is missing in the feature set of virtio_blk.
The not in front of virtio_has_feature() is wrong.
Could you, please, retest with this diff:
diff --git a/drivers/virtio/virtio_blk.c b/drivers/virtio/virtio_blk.c
index 4224e3c17f4..ec2e28b54f7 100644
--- a/drivers/virtio/virtio_blk.c
+++ b/drivers/virtio/virtio_blk.c
@@ -26,6 +26,7 @@ struct virtio_blk_priv {
};
static const u32 feature[] = {
+ VIRTIO_BLK_F_BLK_SIZE,
VIRTIO_BLK_F_WRITE_ZEROES
};
@@ -194,7 +195,7 @@ static int virtio_blk_probe(struct udevice *dev)
virtio_cread(dev, struct virtio_blk_config, capacity, &cap);
desc->lba = cap;
- if (!virtio_has_feature(dev, VIRTIO_BLK_F_BLK_SIZE)) {
+ if (virtio_has_feature(dev, VIRTIO_BLK_F_BLK_SIZE)) {
virtio_cread(dev, struct virtio_blk_config, blk_size,
&blk_size);
desc->blksz = blk_size;
if (!is_power_of_2(blk_size) || desc->blksz < 512)
Best regards
Heinrich
+ virtio_cread(dev, struct virtio_blk_config, blk_size,
&blk_size);
+ desc->blksz = blk_size;
+ if (!is_power_of_2(blk_size) || desc->blksz < 512)
+ return -EIO;
+ } else {
+ desc->blksz = 512;
+ }
+ desc->log2blksz = LOG2(desc->blksz);
+ priv->blksz_shift = desc->log2blksz - 9;
+ desc->lba >>= priv->blksz_shift;
return 0;
}
