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SubjectRe: [PATCH] remoteproc: qcom_q6v5_mss: map/unmap metadata region before/after use
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Hey Matthias,
Thanks for taking time to review the patch.

On 5/6/22 11:37 PM, Matthias Kaehlcke wrote:
> On Fri, May 06, 2022 at 07:21:26PM +0530, 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>
>
> Should this have a 'Fixes:' tag
It ideally should have but similar to what we did for mba and mpss
region map/unmap, it would be a ugly backport since it would point to
the very first commit. We can agree to do a backport if it's ever
reported upstream on any of the older SoCs.

-Sibi

>
>> ---
>> drivers/remoteproc/qcom_q6v5_mss.c | 43 +++++++++++++++++++++++++++++++-------
>> 1 file changed, 35 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/remoteproc/qcom_q6v5_mss.c b/drivers/remoteproc/qcom_q6v5_mss.c
>> index af217de75e4d..eb34a258b67b 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) {
>> - kfree(metadata);
>> + page = dma_alloc_attrs(qproc->dev, size, &phys, GFP_KERNEL, dma_attrs);
>> + if (!page) {
>> dev_err(qproc->dev, "failed to allocate mdt buffer\n");
>> - return -ENOMEM;
>> + ret = -ENOMEM;
>> + goto free_metadata;
>> + }
>> +
>> + count = PAGE_ALIGN(size) >> PAGE_SHIFT;
>> + pages = kmalloc_array(count, sizeof(struct page *), GFP_KERNEL);
>> + if (!pages) {
>> + ret = -ENOMEM;
>> + goto free_metadata;
>> }
>>
>> - memcpy(ptr, metadata, size);
>> + for (i = 0; i < count; i++)
>> + pages[i] = nth_page(page, i);
>> +
>> + vaddr = vmap(pages, count, flags, dma_pgprot(qproc->dev, PAGE_KERNEL, dma_attrs));
>> + kfree(pages);
>> + if (!vaddr) {
>> + dev_err(qproc->dev, "unable to map memory region: %pa+%zx\n", &phys, size);
>> + ret = -EBUSY;
>> + goto free_metadata;
>> + }
>> +
>> + memcpy(vaddr, metadata, size);
>> +
>> + vunmap(vaddr);
>>
>> /* Hypervisor mapping to access metadata by modem */
>> mdata_perm = BIT(QCOM_SCM_VMID_HLOS);
>> @@ -982,7 +1008,8 @@ 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);
>> + dma_free_attrs(qproc->dev, size, page, phys, dma_attrs);
>> +free_metadata:
>> kfree(metadata);
>>
>> return ret < 0 ? ret : 0;
>> --
>> 2.7.4
>>

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