Re: [PATCH V3 05/10] remoteproc: qcom_q6v5_mss: Use a carveout to authenticate modem headers

Manivannan Sadhasivam
2023-01-11T11:59:13Z

On Wed, Jan 11, 2023 at 05:13:32PM +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>

> ---
>
> v3:
> * Drop revert no_kernel_mapping since it's already on the list [Mani]

I thought you are going to include Christoph's patch into your series. That way
all the patches will be in the same series, makig life easier for Bjorn.

Thanks,
Mani

> * kfree metadata from the branch for parity
>
> drivers/remoteproc/qcom_q6v5_mss.c | 48 ++++++++++++++++++++++++++----
> 1 file changed, 42 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/remoteproc/qcom_q6v5_mss.c b/drivers/remoteproc/qcom_q6v5_mss.c
> index e2f765f87ec9..e25d44e20ae7 100644
> --- a/drivers/remoteproc/qcom_q6v5_mss.c
> +++ b/drivers/remoteproc/qcom_q6v5_mss.c
> @@ -215,6 +215,7 @@ struct q6v5 {
> size_t mba_size;
> size_t dp_size;
>
> + phys_addr_t mdata_phys;
> phys_addr_t mpss_phys;
> phys_addr_t mpss_reloc;
> size_t mpss_size;
> @@ -973,15 +974,29 @@ 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) {
> + phys = qproc->mdata_phys;
> + ptr = memremap(qproc->mdata_phys, size, MEMREMAP_WC);
> + if (!ptr) {
> + kfree(metadata);
> + dev_err(qproc->dev, "unable to map memory region: %pa+%zx\n",
> + &qproc->mdata_phys, size);
> + return -EBUSY;
> + }
> + } else {
> + 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;
> + }
> }
>
> 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 +1025,8 @@ 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);
> kfree(metadata);
>
> return ret < 0 ? ret : 0;
> @@ -1893,6 +1909,26 @@ 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;
> +
> + ret = of_address_to_resource(node, 0, &r);
> + of_node_put(node);
> + if (ret) {
> + dev_err(qproc->dev, "unable to resolve metadata region\n");
> + return ret;
> + }
> +
> + qproc->mdata_phys = r.start;
> +
> return 0;
> }
>
> --
> 2.17.1
>

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