[PATCH v2 0/2] misc: fastrpc: FastRPC reserved memory assignment for SDM845 SLPI

[PATCH v2 0/2] misc: fastrpc: FastRPC reserved memory assignment for SDM845 SLPI

[Dylan Van Assche]

* About *

The Qualcomm SDM845 SoC has a separate SLPI (Sensor Low Power Island)
DSP for sensors connected to the SoC which is responsible for exposing
sensors to userspace, power saving, and other features. 
While sensors are connected to GPIOs of the SoC, they cannot be used
because the hypervisor blocks direct access to the sensors, thus the 
DSP must be used to access any sensor on this SoC. The SLPI DSP uses a
GLink edge (dsps) to communicate with the host and has a FastRPC interface
to load files from the host filesystem such as sensor configuration files.
The FastRPC interface does not use regular FastRPC Compute Banks
but instead uses an allocated CMA region through which communication happens.

* Changes *

This patchseries add support to the FastRPC for assigning a coherent memory
region to a DSP via the hypervisor with the correct permissions.
This is necessary to support the SLPI found in the Qualcomm SDM845 SoC which
does not have dedicated FastRPC Compute Banks, in contrast to newer SoCs,
but uses a memory region instead when allocating buffers.

* Related patches *

1. Remoteproc changes to support the SLPI DSP in SDM845:
https://lore.kernel.org/linux-remoteproc/20230325132117.19733-1-me@dylanvanassche.be/
2. DTS changes (v1):
https://lore.kernel.org/linux-devicetree/20230325135114.21688-1-me@dylanvanassche.be/

This serie does not depend on any serie, but all of them are necessary
to enable the feature in the end.

* Changelog *

Changes in v2:

- Removed double blank lines
- Dropped dt-bindings property as it is not needed for driver behavior
- Add additional patch to allocate buffers via CMA memory for DSPs
  without dedicated FastRPC Compute Banks.

Kind regards,
Dylan Van Assche

Dylan Van Assche (2):
  misc: fastrpc: support complete DMA pool access to the DSP
  misc: fastrpc: use coherent pool for untranslated Compute Banks

 drivers/misc/fastrpc.c | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

-- 
2.39.2

[PATCH v2 1/2] misc: fastrpc: support complete DMA pool access to the DSP

[Dylan Van Assche]

To support FastRPC Context Banks which aren't mapped via the SMMU,
make the whole reserved memory region available to the DSP to allow
access to coherent buffers.

This is performed by assigning the memory to the DSP via a hypervisor
call to set the correct permissions for the Virtual Machines on the DSP.
This is only necessary when a memory region is provided for SLPI DSPs
so guard this with a domain ID check.

Signed-off-by: Dylan Van Assche <me@dylanvanassche.be>
---
 drivers/misc/fastrpc.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index f48466960f1b..caf2ae556956 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -2231,6 +2231,8 @@ static int fastrpc_rpmsg_probe(struct rpmsg_device *rpdev)
 	int i, err, domain_id = -1, vmcount;
 	const char *domain;
 	bool secure_dsp;
+	struct device_node *rmem_node;
+	struct reserved_mem *rmem;
 	unsigned int vmids[FASTRPC_MAX_VMIDS];
 
 	err = of_property_read_string(rdev->of_node, "label", &domain);
@@ -2274,6 +2276,20 @@ static int fastrpc_rpmsg_probe(struct rpmsg_device *rpdev)
 		}
 	}
 
+	rmem_node = of_parse_phandle(rdev->of_node, "memory-region", 0);
+	dev_info(rdev, "ASSIGNING MEMORY\n");
+	if (domain_id == SDSP_DOMAIN_ID && rmem_node) {
+		rmem = of_reserved_mem_lookup(rmem_node);
+		if (!rmem)
+			return -EINVAL;
+
+		dev_info(rdev, "ASSIGNING MEMORY START\n");
+		qcom_scm_assign_mem(rmem->base, rmem->size, &data->perms,
+				    data->vmperms, data->vmcount);
+
+		dev_info(rdev, "ASSIGNING MEMORY END\n");
+	}
+
 	secure_dsp = !(of_property_read_bool(rdev->of_node, "qcom,non-secure-domain"));
 	data->secure = secure_dsp;
 
-- 
2.39.2

[PATCH v2 2/2] misc: fastrpc: use coherent pool for untranslated Compute Banks

[Dylan Van Assche]

Use fastrpc_remote_heap_alloc to allocate from the FastRPC device
instead of the Compute Bank when the session ID is 0. This ensures
that the allocation is inside the coherent DMA pool which is already
accessible to the DSP. This is necessary to support FastRPC devices
which do not have dedicated Compute Banks such as the SLPI on the SDM845.
The latter uses an allocated CMA region instead of FastRPC Compute Banks.

Signed-off-by: Dylan Van Assche <me@dylanvanassche.be>
---
 drivers/misc/fastrpc.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index caf2ae556956..b7ddf6b90022 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -939,7 +939,10 @@ static int fastrpc_get_args(u32 kernel, struct fastrpc_invoke_ctx *ctx)
 
 	ctx->msg_sz = pkt_size;
 
-	err = fastrpc_buf_alloc(ctx->fl, dev, pkt_size, &ctx->buf);
+	if (ctx->fl->sctx->sid)
+		err = fastrpc_buf_alloc(ctx->fl, dev, pkt_size, &ctx->buf);
+	else
+		err = fastrpc_remote_heap_alloc(ctx->fl, dev, pkt_size, &ctx->buf);
 	if (err)
 		return err;
 
-- 
2.39.2

Re: [PATCH v2 1/2] misc: fastrpc: support complete DMA pool access to the DSP

[Caleb Connolly]

On 27/03/2023 19:42, Dylan Van Assche wrote:
> To support FastRPC Context Banks which aren't mapped via the SMMU,
> make the whole reserved memory region available to the DSP to allow
> access to coherent buffers.
> 
> This is performed by assigning the memory to the DSP via a hypervisor
> call to set the correct permissions for the Virtual Machines on the DSP.
> This is only necessary when a memory region is provided for SLPI DSPs
> so guard this with a domain ID check.
> 
> Signed-off-by: Dylan Van Assche <me@dylanvanassche.be>

Hi Dylan!

Personally pretty excited to LGTM. Please drop the noisy debug prints.
With those fixed

Reviewed-by: Caleb Connolly <caleb.connolly@linaro.org>
> ---
>  drivers/misc/fastrpc.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
> index f48466960f1b..caf2ae556956 100644
> --- a/drivers/misc/fastrpc.c
> +++ b/drivers/misc/fastrpc.c
> @@ -2231,6 +2231,8 @@ static int fastrpc_rpmsg_probe(struct rpmsg_device *rpdev)
>  	int i, err, domain_id = -1, vmcount;
>  	const char *domain;
>  	bool secure_dsp;
> +	struct device_node *rmem_node;
> +	struct reserved_mem *rmem;
>  	unsigned int vmids[FASTRPC_MAX_VMIDS];
>  
>  	err = of_property_read_string(rdev->of_node, "label", &domain);
> @@ -2274,6 +2276,20 @@ static int fastrpc_rpmsg_probe(struct rpmsg_device *rpdev)
>  		}
>  	}
>  
> +	rmem_node = of_parse_phandle(rdev->of_node, "memory-region", 0);
> +	dev_info(rdev, "ASSIGNING MEMORY\n");

				^^
> +	if (domain_id == SDSP_DOMAIN_ID && rmem_node) {
> +		rmem = of_reserved_mem_lookup(rmem_node);
> +		if (!rmem)
> +			return -EINVAL;
> +
> +		dev_info(rdev, "ASSIGNING MEMORY START\n");

				^^
> +		qcom_scm_assign_mem(rmem->base, rmem->size, &data->perms,
> +				    data->vmperms, data->vmcount);
> +
> +		dev_info(rdev, "ASSIGNING MEMORY END\n");

				^^
> +	}
> +
>  	secure_dsp = !(of_property_read_bool(rdev->of_node, "qcom,non-secure-domain"));
>  	data->secure = secure_dsp;
>  

-- 
Kind Regards,
Caleb (they/them)

Re: [PATCH v2 2/2] misc: fastrpc: use coherent pool for untranslated Compute Banks

[Caleb Connolly]

On 27/03/2023 19:42, Dylan Van Assche wrote:
> Use fastrpc_remote_heap_alloc to allocate from the FastRPC device
> instead of the Compute Bank when the session ID is 0. This ensures
> that the allocation is inside the coherent DMA pool which is already
> accessible to the DSP. This is necessary to support FastRPC devices
> which do not have dedicated Compute Banks such as the SLPI on the SDM845.
> The latter uses an allocated CMA region instead of FastRPC Compute Banks.
>
> Signed-off-by: Dylan Van Assche <me@dylanvanassche.be>

Reviewed-by: Caleb Connolly <caleb.connolly@linaro.org>
> ---
>  drivers/misc/fastrpc.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
> index caf2ae556956..b7ddf6b90022 100644
> --- a/drivers/misc/fastrpc.c
> +++ b/drivers/misc/fastrpc.c
> @@ -939,7 +939,10 @@ static int fastrpc_get_args(u32 kernel, struct fastrpc_invoke_ctx *ctx)
>
>  	ctx->msg_sz = pkt_size;
>
> -	err = fastrpc_buf_alloc(ctx->fl, dev, pkt_size, &ctx->buf);
> +	if (ctx->fl->sctx->sid)
> +		err = fastrpc_buf_alloc(ctx->fl, dev, pkt_size, &ctx->buf);
> +	else
> +		err = fastrpc_remote_heap_alloc(ctx->fl, dev, pkt_size, &ctx->buf);
>  	if (err)
>  		return err;
>
> --
> 2.39.2
>

--
Kind Regards,
Caleb