[U-Boot] [PATCH] nvme: Fix PRP Offset Invalid

[Bin Meng]

HI Aaron,

On Thu, Aug 22, 2019 at 5:12 PM Aaron Williams <awilliams at marvell.com> wrote:
>
> When large writes take place I saw a Samsung EVO 970+ return a status
> value of 0x13, PRP Offset Invalid.  I tracked this down to the
> improper handling of PRP entries.  The blocks the PRP entries are
> placed in cannot cross a page boundary and thus should be allocated
> on page boundaries.  This is how the Linux kernel driver works.
>
> With this patch, the PRP pool is allocated on a page boundary and
> other than the very first allocation, the pool size is a multiple of
> the page size.  Each page can hold (4096 / 8) - 1 entries since the
> last entry must point to the next page in the pool.
>
> Signed-off-by: Aaron Williams <awilliams at marvell.com>
> ---
>  drivers/nvme/nvme.c | 28 ++++++++++++++++++----------
>  1 file changed, 18 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/nvme/nvme.c b/drivers/nvme/nvme.c
> index d4965e2ef6..bc4cf40b40 100644
> --- a/drivers/nvme/nvme.c
> +++ b/drivers/nvme/nvme.c
> @@ -73,6 +73,9 @@ static int nvme_setup_prps(struct nvme_dev *dev, u64 *prp2,
>         u64 *prp_pool;
>         int length = total_len;
>         int i, nprps;
> +       u32 prps_per_page = (page_size >> 3) - 1;
> +       u32 num_pages;
> +
>         length -= (page_size - offset);
>
>         if (length <= 0) {
> @@ -89,15 +92,19 @@ static int nvme_setup_prps(struct nvme_dev *dev, u64 *prp2,
>         }
>
>         nprps = DIV_ROUND_UP(length, page_size);
> +       num_pages = DIV_ROUND_UP(nprps, prps_per_page);
>
>         if (nprps > dev->prp_entry_num) {
>                 free(dev->prp_pool);
> -               dev->prp_pool = malloc(nprps << 3);
> +               /* Always increase in increments of pages.  It doesn't waste

nits: please use the correct multi-line comment format.

> +                * much memory and reduces the number of allocations.
> +                */
> +               dev->prp_pool = memalign(page_size, num_pages * page_size);
>                 if (!dev->prp_pool) {
>                         printf("Error: malloc prp_pool fail\n");
>                         return -ENOMEM;
>                 }
> -               dev->prp_entry_num = nprps;
> +               dev->prp_entry_num = prps_per_page * num_pages;
>         }
>
>         prp_pool = dev->prp_pool;
> @@ -788,14 +795,6 @@ static int nvme_probe(struct udevice *udev)
>         }
>         memset(ndev->queues, 0, NVME_Q_NUM * sizeof(struct nvme_queue *));
>
> -       ndev->prp_pool = malloc(MAX_PRP_POOL);
> -       if (!ndev->prp_pool) {
> -               ret = -ENOMEM;
> -               printf("Error: %s: Out of memory!\n", udev->name);
> -               goto free_nvme;
> -       }
> -       ndev->prp_entry_num = MAX_PRP_POOL >> 3;
> -
>         ndev->cap = nvme_readq(&ndev->bar->cap);
>         ndev->q_depth = min_t(int, NVME_CAP_MQES(ndev->cap) + 1, NVME_Q_DEPTH);
>         ndev->db_stride = 1 << NVME_CAP_STRIDE(ndev->cap);
> @@ -805,6 +804,15 @@ static int nvme_probe(struct udevice *udev)
>         if (ret)
>                 goto free_queue;
>
> +       /* Allocate after the page size is known */
> +       ndev->prp_pool = memalign(ndev->page_size, MAX_PRP_POOL);
> +       if (!ndev->prp_pool) {
> +               ret = -ENOMEM;
> +               printf("Error: %s: Out of memory!\n", udev->name);
> +               goto free_nvme;
> +       }
> +       ndev->prp_entry_num = MAX_PRP_POOL >> 3;
> +
>         ret = nvme_setup_io_queues(ndev);
>         if (ret)
>                 goto free_queue;
> --

Other than above nits, you can include my:
Reviewed-by: Bin Meng <bmeng.cn at gmail.com>

in your next version patch. Thanks!

Regards,
Bin