Re: [PATCH V4 06/11] remoteproc: qcom_q6v5_mss: Use a carveout to authenticate modem headers

[Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>]

On Tue, Jan 17, 2023 at 02:28:35PM +0530, Sibi Sankar wrote:
> Any access to the dynamically allocated metadata region by the application
> processor after assigning it to the remote Q6 will result in a XPU
> violation. Fix this by replacing the dynamically allocated memory region
> with a no-map carveout and unmap the modem metadata memory region before
> passing control to the remote Q6.
> 
> Reported-and-tested-by: Amit Pundir <amit.pundir@linaro.org>
> Fixes: 6c5a9dc2481b ("remoteproc: qcom: Make secure world call for mem ownership switch")
> Signed-off-by: Sibi Sankar <quic_sibis@quicinc.com>

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Thanks,
Mani

> ---
> 
> v4:
>  * Use size/alloc-ranges instead of a specific address [Bjorn]
>  * Include size checks
> 
> v3:
>  * Drop revert no_kernel_mapping since it's already on the list [Mani]
>  * kfree metadata from the branch for parity
> 
>  drivers/remoteproc/qcom_q6v5_mss.c | 59 +++++++++++++++++++++++++++---
>  1 file changed, 53 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/remoteproc/qcom_q6v5_mss.c b/drivers/remoteproc/qcom_q6v5_mss.c
> index e2f765f87ec9..292e22f58df3 100644
> --- a/drivers/remoteproc/qcom_q6v5_mss.c
> +++ b/drivers/remoteproc/qcom_q6v5_mss.c
> @@ -17,6 +17,7 @@
>  #include <linux/module.h>
>  #include <linux/of_address.h>
>  #include <linux/of_device.h>
> +#include <linux/of_reserved_mem.h>
>  #include <linux/platform_device.h>
>  #include <linux/pm_domain.h>
>  #include <linux/pm_runtime.h>
> @@ -215,6 +216,9 @@ struct q6v5 {
>  	size_t mba_size;
>  	size_t dp_size;
>  
> +	phys_addr_t mdata_phys;
> +	size_t mdata_size;
> +
>  	phys_addr_t mpss_phys;
>  	phys_addr_t mpss_reloc;
>  	size_t mpss_size;
> @@ -973,15 +977,35 @@ static int q6v5_mpss_init_image(struct q6v5 *qproc, const struct firmware *fw,
>  	if (IS_ERR(metadata))
>  		return PTR_ERR(metadata);
>  
> -	ptr = dma_alloc_attrs(qproc->dev, size, &phys, GFP_KERNEL, dma_attrs);
> -	if (!ptr) {
> -		kfree(metadata);
> -		dev_err(qproc->dev, "failed to allocate mdt buffer\n");
> -		return -ENOMEM;
> +	if (qproc->mdata_phys) {
> +		if (size > qproc->mdata_size) {
> +			ret = -EINVAL;
> +			dev_err(qproc->dev, "metadata size outside memory range\n");
> +			goto free_metadata;
> +		}
> +
> +		phys = qproc->mdata_phys;
> +		ptr = memremap(qproc->mdata_phys, size, MEMREMAP_WC);
> +		if (!ptr) {
> +			ret = -EBUSY;
> +			dev_err(qproc->dev, "unable to map memory region: %pa+%zx\n",
> +				&qproc->mdata_phys, size);
> +			goto free_metadata;
> +		}
> +	} else {
> +		ptr = dma_alloc_attrs(qproc->dev, size, &phys, GFP_KERNEL, dma_attrs);
> +		if (!ptr) {
> +			ret = -ENOMEM;
> +			dev_err(qproc->dev, "failed to allocate mdt buffer\n");
> +			goto free_metadata;
> +		}
>  	}
>  
>  	memcpy(ptr, metadata, size);
>  
> +	if (qproc->mdata_phys)
> +		memunmap(ptr);
> +
>  	/* Hypervisor mapping to access metadata by modem */
>  	mdata_perm = BIT(QCOM_SCM_VMID_HLOS);
>  	ret = q6v5_xfer_mem_ownership(qproc, &mdata_perm, false, true,
> @@ -1010,7 +1034,9 @@ static int q6v5_mpss_init_image(struct q6v5 *qproc, const struct firmware *fw,
>  			 "mdt buffer not reclaimed system may become unstable\n");
>  
>  free_dma_attrs:
> -	dma_free_attrs(qproc->dev, size, ptr, phys, dma_attrs);
> +	if (!qproc->mdata_phys)
> +		dma_free_attrs(qproc->dev, size, ptr, phys, dma_attrs);
> +free_metadata:
>  	kfree(metadata);
>  
>  	return ret < 0 ? ret : 0;
> @@ -1847,6 +1873,7 @@ static int q6v5_init_reset(struct q6v5 *qproc)
>  static int q6v5_alloc_memory_region(struct q6v5 *qproc)
>  {
>  	struct device_node *child;
> +	struct reserved_mem *rmem;
>  	struct device_node *node;
>  	struct resource r;
>  	int ret;
> @@ -1893,6 +1920,26 @@ static int q6v5_alloc_memory_region(struct q6v5 *qproc)
>  	qproc->mpss_phys = qproc->mpss_reloc = r.start;
>  	qproc->mpss_size = resource_size(&r);
>  
> +	if (!child) {
> +		node = of_parse_phandle(qproc->dev->of_node, "memory-region", 2);
> +	} else {
> +		child = of_get_child_by_name(qproc->dev->of_node, "metadata");
> +		node = of_parse_phandle(child, "memory-region", 0);
> +		of_node_put(child);
> +	}
> +
> +	if (!node)
> +		return 0;
> +
> +	rmem = of_reserved_mem_lookup(node);
> +	if (!rmem) {
> +		dev_err(qproc->dev, "unable to resolve metadata region\n");
> +		return -EINVAL;
> +	}
> +
> +	qproc->mdata_phys = rmem->base;
> +	qproc->mdata_size = rmem->size;
> +
>  	return 0;
>  }
>  
> -- 
> 2.17.1
> 

-- 
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