linux-kernel - [PATCH] vdpa_sim_blk: add `capacity` module parameter

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Message-ID: <20240705112821.144819-1-sgarzare@redhat.com>
Date: Fri,  5 Jul 2024 13:28:21 +0200
From: Stefano Garzarella <sgarzare@...hat.com>
To: virtualization@...ts.linux.dev
Cc: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
	Jason Wang <jasowang@...hat.com>,
	linux-kernel@...r.kernel.org,
	"Michael S. Tsirkin" <mst@...hat.com>,
	Eugenio Pérez <eperezma@...hat.com>,
	Stefano Garzarella <sgarzare@...hat.com>
Subject: [PATCH] vdpa_sim_blk: add `capacity` module parameter

The vDPA block simulator always allocated a 128 MiB ram-disk, but some
filesystems (e.g. XFS) may require larger minimum sizes (see
https://issues.redhat.com/browse/RHEL-45951).

So to allow us to test these filesystems, let's add a module parameter
to control the size of the simulated virtio-blk devices.
The value is mapped directly to the `capacity` field of the virtio-blk
configuration space, so it must be expressed in sector numbers of 512
bytes.

The default value (0x40000) is the same as the previous value, so the
behavior without setting `capacity` remains unchanged.

Before this patch or with this patch without setting `capacity`:
  $ modprobe vdpa-sim-blk
  $ vdpa dev add mgmtdev vdpasim_blk name blk0
  virtio_blk virtio6: 1/0/0 default/read/poll queues
  virtio_blk virtio6: [vdb] 262144 512-byte logical blocks (134 MB/128 MiB)

After this patch:
  $ modprobe vdpa-sim-blk capacity=614400
  $ vdpa dev add mgmtdev vdpasim_blk name blk0
  virtio_blk virtio6: 1/0/0 default/read/poll queues
  virtio_blk virtio6: [vdb] 614400 512-byte logical blocks (315 MB/300 MiB)

Signed-off-by: Stefano Garzarella <sgarzare@...hat.com>
---
 drivers/vdpa/vdpa_sim/vdpa_sim_blk.c | 25 +++++++++++++------------
 1 file changed, 13 insertions(+), 12 deletions(-)

diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c b/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c
index b137f3679343..18f390149836 100644
--- a/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c
+++ b/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c
@@ -33,7 +33,6 @@
 				 (1ULL << VIRTIO_BLK_F_DISCARD)  | \
 				 (1ULL << VIRTIO_BLK_F_WRITE_ZEROES))
 
-#define VDPASIM_BLK_CAPACITY	0x40000
 #define VDPASIM_BLK_SIZE_MAX	0x1000
 #define VDPASIM_BLK_SEG_MAX	32
 #define VDPASIM_BLK_DWZ_MAX_SECTORS UINT_MAX
@@ -43,6 +42,10 @@
 #define VDPASIM_BLK_AS_NUM	1
 #define VDPASIM_BLK_GROUP_NUM	1
 
+static unsigned long capacity = 0x40000;
+module_param(capacity, ulong, 0444);
+MODULE_PARM_DESC(capacity, "virtio-blk device capacity (in 512-byte sectors)");
+
 struct vdpasim_blk {
 	struct vdpasim vdpasim;
 	void *buffer;
@@ -79,10 +82,10 @@ static void vdpasim_blk_buffer_unlock(struct vdpasim_blk *blk)
 static bool vdpasim_blk_check_range(struct vdpasim *vdpasim, u64 start_sector,
 				    u64 num_sectors, u64 max_sectors)
 {
-	if (start_sector > VDPASIM_BLK_CAPACITY) {
+	if (start_sector > capacity) {
 		dev_dbg(&vdpasim->vdpa.dev,
-			"starting sector exceeds the capacity - start: 0x%llx capacity: 0x%x\n",
-			start_sector, VDPASIM_BLK_CAPACITY);
+			"starting sector exceeds the capacity - start: 0x%llx capacity: 0x%lx\n",
+			start_sector, capacity);
 	}
 
 	if (num_sectors > max_sectors) {
@@ -92,10 +95,10 @@ static bool vdpasim_blk_check_range(struct vdpasim *vdpasim, u64 start_sector,
 		return false;
 	}
 
-	if (num_sectors > VDPASIM_BLK_CAPACITY - start_sector) {
+	if (num_sectors > capacity - start_sector) {
 		dev_dbg(&vdpasim->vdpa.dev,
-			"request exceeds the capacity - start: 0x%llx num: 0x%llx capacity: 0x%x\n",
-			start_sector, num_sectors, VDPASIM_BLK_CAPACITY);
+			"request exceeds the capacity - start: 0x%llx num: 0x%llx capacity: 0x%lx\n",
+			start_sector, num_sectors, capacity);
 		return false;
 	}
 
@@ -369,7 +372,7 @@ static void vdpasim_blk_get_config(struct vdpasim *vdpasim, void *config)
 
 	memset(config, 0, sizeof(struct virtio_blk_config));
 
-	blk_config->capacity = cpu_to_vdpasim64(vdpasim, VDPASIM_BLK_CAPACITY);
+	blk_config->capacity = cpu_to_vdpasim64(vdpasim, capacity);
 	blk_config->size_max = cpu_to_vdpasim32(vdpasim, VDPASIM_BLK_SIZE_MAX);
 	blk_config->seg_max = cpu_to_vdpasim32(vdpasim, VDPASIM_BLK_SEG_MAX);
 	blk_config->num_queues = cpu_to_vdpasim16(vdpasim, VDPASIM_BLK_VQ_NUM);
@@ -437,8 +440,7 @@ static int vdpasim_blk_dev_add(struct vdpa_mgmt_dev *mdev, const char *name,
 	if (blk->shared_backend) {
 		blk->buffer = shared_buffer;
 	} else {
-		blk->buffer = kvzalloc(VDPASIM_BLK_CAPACITY << SECTOR_SHIFT,
-				       GFP_KERNEL);
+		blk->buffer = kvzalloc(capacity << SECTOR_SHIFT, GFP_KERNEL);
 		if (!blk->buffer) {
 			ret = -ENOMEM;
 			goto put_dev;
@@ -495,8 +497,7 @@ static int __init vdpasim_blk_init(void)
 		goto parent_err;
 
 	if (shared_backend) {
-		shared_buffer = kvzalloc(VDPASIM_BLK_CAPACITY << SECTOR_SHIFT,
-					 GFP_KERNEL);
+		shared_buffer = kvzalloc(capacity << SECTOR_SHIFT, GFP_KERNEL);
 		if (!shared_buffer) {
 			ret = -ENOMEM;
 			goto mgmt_dev_err;
-- 
2.45.2