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SubjectRe: [PATCH v2] remoteproc: qcom_q6v5_mss: map/unmap metadata region before/after use
On Wed 11 May 00:57 CDT 2022, Sibi Sankar wrote:

> The application processor accessing the dynamically assigned metadata
> region after assigning it to the remote Q6 would lead to an XPU violation.
> Fix this by un-mapping the metadata region post firmware header copy. The
> metadata region is freed only after the modem Q6 is done with fw header
> authentication.
>
> Signed-off-by: Sibi Sankar <quic_sibis@quicinc.com>

Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>

> ---
>
> V2:
> * Fix error when MSS is built as a module [Kernel Test Bot]
> * Fixup cleanup errors
>
> drivers/remoteproc/qcom_q6v5_mss.c | 38 ++++++++++++++++++++++++++++++++------
> 1 file changed, 32 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/remoteproc/qcom_q6v5_mss.c b/drivers/remoteproc/qcom_q6v5_mss.c
> index af217de75e4d..4b37e11fbb03 100644
> --- a/drivers/remoteproc/qcom_q6v5_mss.c
> +++ b/drivers/remoteproc/qcom_q6v5_mss.c
> @@ -10,6 +10,7 @@
> #include <linux/clk.h>
> #include <linux/delay.h>
> #include <linux/devcoredump.h>
> +#include <linux/dma-map-ops.h>
> #include <linux/dma-mapping.h>
> #include <linux/interrupt.h>
> #include <linux/kernel.h>
> @@ -932,27 +933,52 @@ static void q6v5proc_halt_axi_port(struct q6v5 *qproc,
> static int q6v5_mpss_init_image(struct q6v5 *qproc, const struct firmware *fw,
> const char *fw_name)
> {
> - unsigned long dma_attrs = DMA_ATTR_FORCE_CONTIGUOUS;
> + unsigned long dma_attrs = DMA_ATTR_FORCE_CONTIGUOUS | DMA_ATTR_NO_KERNEL_MAPPING;
> + unsigned long flags = VM_DMA_COHERENT | VM_FLUSH_RESET_PERMS;
> + struct page **pages;
> + struct page *page;
> dma_addr_t phys;
> void *metadata;
> int mdata_perm;
> int xferop_ret;
> size_t size;
> - void *ptr;
> + void *vaddr;
> + int count;
> int ret;
> + int i;
>
> metadata = qcom_mdt_read_metadata(fw, &size, fw_name, qproc->dev);
> if (IS_ERR(metadata))
> return PTR_ERR(metadata);
>
> - ptr = dma_alloc_attrs(qproc->dev, size, &phys, GFP_KERNEL, dma_attrs);
> - if (!ptr) {
> + page = dma_alloc_attrs(qproc->dev, size, &phys, GFP_KERNEL, dma_attrs);
> + if (!page) {
> kfree(metadata);
> dev_err(qproc->dev, "failed to allocate mdt buffer\n");
> return -ENOMEM;
> }
>
> - memcpy(ptr, metadata, size);
> + count = PAGE_ALIGN(size) >> PAGE_SHIFT;
> + pages = kmalloc_array(count, sizeof(struct page *), GFP_KERNEL);
> + if (!pages) {
> + ret = -ENOMEM;
> + goto free_dma_attrs;
> + }
> +
> + for (i = 0; i < count; i++)
> + pages[i] = nth_page(page, i);
> +
> + vaddr = vmap(pages, count, flags, pgprot_dmacoherent(PAGE_KERNEL));
> + kfree(pages);
> + if (!vaddr) {
> + dev_err(qproc->dev, "unable to map memory region: %pa+%zx\n", &phys, size);
> + ret = -EBUSY;
> + goto free_dma_attrs;
> + }
> +
> + memcpy(vaddr, metadata, size);
> +
> + vunmap(vaddr);
>
> /* Hypervisor mapping to access metadata by modem */
> mdata_perm = BIT(QCOM_SCM_VMID_HLOS);
> @@ -982,7 +1008,7 @@ 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);
> + dma_free_attrs(qproc->dev, size, page, phys, dma_attrs);
> kfree(metadata);
>
> return ret < 0 ? ret : 0;
> --
> 2.7.4
>

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