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Message-ID: <20240705073017-mutt-send-email-mst@kernel.org>
Date: Fri, 5 Jul 2024 07:30:51 -0400
From: "Michael S. Tsirkin" <mst@...hat.com>
To: Stefano Garzarella <sgarzare@...hat.com>
Cc: virtualization@...ts.linux.dev, Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
Jason Wang <jasowang@...hat.com>, linux-kernel@...r.kernel.org,
Eugenio PĂ©rez <eperezma@...hat.com>
Subject: Re: [PATCH] vdpa_sim_blk: add `capacity` module parameter
On Fri, Jul 05, 2024 at 01:28:21PM +0200, Stefano Garzarella wrote:
> 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>
What a hack. Cindy was working on adding control over config
space, why can't that be used?
> ---
> 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
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