[PATCH v1] dmaengine: idxd: drain ATS translations when disabling WQ

[PATCH v1] dmaengine: idxd: drain ATS translations when disabling WQ

[Vinicius Costa Gomes]

From: Nikhil Rao <nikhil.rao@intel.com>

There's an errata[1], for the Disable WQ command that it
does not guaranteee that address translations are drained. If WQ
configuration is updated, pending address translations can use an
updated WQ configuration, resulting an invalid translation response
that is cached in the device translation cache.

Replace the Disable WQ command with a Drain WQ command followed by a
Reset WQ command, this guarantees that all ATS translations are
drained from the device before changing WQ configuration.

[1] https://cdrdv2.intel.com/v1/dl/getcontent/843306 ("Intel DSA May
Cause Invalid Translation Caching")

Signed-off-by: Nikhil Rao <nikhil.rao@intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
---
 drivers/dma/idxd/device.c | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/idxd/device.c b/drivers/dma/idxd/device.c
index 5cf419fe6b46..c2cdf41b6e57 100644
--- a/drivers/dma/idxd/device.c
+++ b/drivers/dma/idxd/device.c
@@ -16,6 +16,7 @@ static void idxd_cmd_exec(struct idxd_device *idxd, int cmd_code, u32 operand,
 			  u32 *status);
 static void idxd_device_wqs_clear_state(struct idxd_device *idxd);
 static void idxd_wq_disable_cleanup(struct idxd_wq *wq);
+static int idxd_wq_config_write(struct idxd_wq *wq);
 
 /* Interrupt control bits */
 void idxd_unmask_error_interrupts(struct idxd_device *idxd)
@@ -215,14 +216,28 @@ int idxd_wq_disable(struct idxd_wq *wq, bool reset_config)
 		return 0;
 	}
 
+	/*
+	 * Disable WQ does not drain address translations, if WQ attributes are
+	 * changed before translations are drained, pending translations can
+	 * be issued using updated WQ attibutes, resulting in invalid
+	 * translations being cached in the device translation cache.
+	 *
+	 * To make sure pending translations are drained before WQ
+	 * attributes are changed, we use a WQ Drain followed by WQ Reset and
+	 * then restore the WQ configuration.
+	 */
+	idxd_wq_drain(wq);
+
 	operand = BIT(wq->id % 16) | ((wq->id / 16) << 16);
-	idxd_cmd_exec(idxd, IDXD_CMD_DISABLE_WQ, operand, &status);
+	idxd_cmd_exec(idxd, IDXD_CMD_RESET_WQ, operand, &status);
 
 	if (status != IDXD_CMDSTS_SUCCESS) {
-		dev_dbg(dev, "WQ disable failed: %#x\n", status);
+		dev_dbg(dev, "WQ reset failed: %#x\n", status);
 		return -ENXIO;
 	}
 
+	idxd_wq_config_write(wq);
+
 	if (reset_config)
 		idxd_wq_disable_cleanup(wq);
 	clear_bit(wq->id, idxd->wq_enable_map);
-- 
2.51.0

Re: [PATCH v1] dmaengine: idxd: drain ATS translations when disabling WQ

[Dave Jiang]

On 9/30/25 6:22 PM, Vinicius Costa Gomes wrote:
> From: Nikhil Rao <nikhil.rao@intel.com>
> 
> There's an errata[1], for the Disable WQ command that it
> does not guaranteee that address translations are drained. If WQ
> configuration is updated, pending address translations can use an
> updated WQ configuration, resulting an invalid translation response
> that is cached in the device translation cache.
> 
> Replace the Disable WQ command with a Drain WQ command followed by a
> Reset WQ command, this guarantees that all ATS translations are
> drained from the device before changing WQ configuration.
> 
> [1] https://cdrdv2.intel.com/v1/dl/getcontent/843306 ("Intel DSA May
> Cause Invalid Translation Caching")
> 
> Signed-off-by: Nikhil Rao <nikhil.rao@intel.com>
> Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
> Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>

Reviewed-by: Dave Jiang <dave.jiang@intel.com>
> ---
>  drivers/dma/idxd/device.c | 19 +++++++++++++++++--
>  1 file changed, 17 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/dma/idxd/device.c b/drivers/dma/idxd/device.c
> index 5cf419fe6b46..c2cdf41b6e57 100644
> --- a/drivers/dma/idxd/device.c
> +++ b/drivers/dma/idxd/device.c
> @@ -16,6 +16,7 @@ static void idxd_cmd_exec(struct idxd_device *idxd, int cmd_code, u32 operand,
>  			  u32 *status);
>  static void idxd_device_wqs_clear_state(struct idxd_device *idxd);
>  static void idxd_wq_disable_cleanup(struct idxd_wq *wq);
> +static int idxd_wq_config_write(struct idxd_wq *wq);
>  
>  /* Interrupt control bits */
>  void idxd_unmask_error_interrupts(struct idxd_device *idxd)
> @@ -215,14 +216,28 @@ int idxd_wq_disable(struct idxd_wq *wq, bool reset_config)
>  		return 0;
>  	}
>  
> +	/*
> +	 * Disable WQ does not drain address translations, if WQ attributes are
> +	 * changed before translations are drained, pending translations can
> +	 * be issued using updated WQ attibutes, resulting in invalid
> +	 * translations being cached in the device translation cache.
> +	 *
> +	 * To make sure pending translations are drained before WQ
> +	 * attributes are changed, we use a WQ Drain followed by WQ Reset and
> +	 * then restore the WQ configuration.
> +	 */
> +	idxd_wq_drain(wq);
> +
>  	operand = BIT(wq->id % 16) | ((wq->id / 16) << 16);
> -	idxd_cmd_exec(idxd, IDXD_CMD_DISABLE_WQ, operand, &status);
> +	idxd_cmd_exec(idxd, IDXD_CMD_RESET_WQ, operand, &status);
>  
>  	if (status != IDXD_CMDSTS_SUCCESS) {
> -		dev_dbg(dev, "WQ disable failed: %#x\n", status);
> +		dev_dbg(dev, "WQ reset failed: %#x\n", status);
>  		return -ENXIO;
>  	}
>  
> +	idxd_wq_config_write(wq);
> +
>  	if (reset_config)
>  		idxd_wq_disable_cleanup(wq);
>  	clear_bit(wq->id, idxd->wq_enable_map);

Re: [PATCH v1] dmaengine: idxd: drain ATS translations when disabling WQ

[Vinod Koul]

On Tue, 30 Sep 2025 18:22:26 -0700, Vinicius Costa Gomes wrote:
> There's an errata[1], for the Disable WQ command that it
> does not guaranteee that address translations are drained. If WQ
> configuration is updated, pending address translations can use an
> updated WQ configuration, resulting an invalid translation response
> that is cached in the device translation cache.
> 
> Replace the Disable WQ command with a Drain WQ command followed by a
> Reset WQ command, this guarantees that all ATS translations are
> drained from the device before changing WQ configuration.
> 
> [...]

Applied, thanks!

[1/1] dmaengine: idxd: drain ATS translations when disabling WQ
      commit: f80ea8566917c4bb680911db839a170873e5d17c

Best regards,
-- 
~Vinod