Re: [PATCH] dmaengine: idxd: add module parameter to force disable of SVA

Vinod Koul
2021-01-17T06:52:18Z

On 15-01-21, 15:01, Dave Jiang wrote:
> Add a module parameter that overrides the SVA feature enabling. This keeps
> the driver in legacy mode even when intel_iommu=sm_on is set. In this mode,
> the descriptor fields must be programmed with dma_addr_t from the Linux DMA
> API for source, destination, and completion descriptors.
>
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> ---
> drivers/dma/idxd/init.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/dma/idxd/init.c b/drivers/dma/idxd/init.c
> index 25cc947c6179..9687a24ff982 100644
> --- a/drivers/dma/idxd/init.c
> +++ b/drivers/dma/idxd/init.c
> @@ -26,6 +26,10 @@ MODULE_VERSION(IDXD_DRIVER_VERSION);
> MODULE_LICENSE("GPL v2");
> MODULE_AUTHOR("Intel Corporation");
>
> +static bool sva = true;
> +module_param(sva, bool, 0644);
> +MODULE_PARM_DESC(sva, "Toggle SVA support on/off");

Documentation for this please..

> +
> #define DRV_NAME "idxd"
>
> bool support_enqcmd;
> @@ -338,12 +342,14 @@ static int idxd_probe(struct idxd_device *idxd)
> idxd_device_init_reset(idxd);
> dev_dbg(dev, "IDXD reset complete\n");
>
> - if (IS_ENABLED(CONFIG_INTEL_IDXD_SVM)) {
> + if (IS_ENABLED(CONFIG_INTEL_IDXD_SVM) && sva) {
> rc = idxd_enable_system_pasid(idxd);
> if (rc < 0)
> dev_warn(dev, "Failed to enable PASID. No SVA support: %d\n", rc);
> else
> set_bit(IDXD_FLAG_PASID_ENABLED, &idxd->flags);
> + } else if (!sva) {
> + dev_warn(dev, "User forced SVA off via module param.\n");
> }
>
> idxd_read_caps(idxd);
>

--
~Vinod