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Message-ID: <ba258979-0c65-4671-dd01-c1916c26e81b@quicinc.com>
Date: Tue, 13 Dec 2022 21:27:04 +0530
From: Sibi Sankar <quic_sibis@...cinc.com>
To: Robin Murphy <robin.murphy@....com>, <andersson@...nel.org>,
<krzysztof.kozlowski+dt@...aro.org>, <robh+dt@...nel.org>,
<manivannan.sadhasivam@...aro.org>
CC: <agross@...nel.org>, <linux-arm-msm@...r.kernel.org>,
<devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<konrad.dybcio@...ainline.org>, <amit.pundir@...aro.org>,
<regressions@...mhuis.info>, <sumit.semwal@...aro.org>,
<will@...nel.org>, <catalin.marinas@....com>
Subject: Re: [PATCH 4/4] remoteproc: qcom_q6v5_mss: Use a carveout to
authenticate modem headers
Hey Robin,
Thanks for taking time to review the series.
On 12/13/22 20:37, Robin Murphy wrote:
> On 2022-12-13 14:07, Sibi Sankar wrote:
>> The memory region allocated using dma_alloc_attr with no kernel mapping
>> attribute set would still be a part of the linear kernel map. Any access
>> to this 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-by: Amit Pundir <amit.pundir@...aro.org>
>> Fixes: 6c5a9dc2481b ("remoteproc: qcom: Make secure world call for mem
>> ownership switch")
>> Signed-off-by: Sibi Sankar <quic_sibis@...cinc.com>
>> ---
>>
>> The addition of the carveout and memunmap is required only on SoCs that
>> mandate memory protection before transferring control to Q6, hence the
>> driver falls back to dynamic memory allocation in the absence of the
>> modem metadata carveout.
>
> The DMA_ATTR_NO_KERNEL_MAPPING stuff is still broken and pointless, so
> I'd expect to see this solution replacing it, not being added alongside.
> It's just silly to say pass the "I don't need a CPU mapping" flag, then
> manually open-code the same CPU mapping you would have got if you
> hadn't, in a way that only works at all when a cacheable alias exists
> anyway.
only a subset of SoCs supported by the driver are affected by
the bug i.e. on the others dma_alloc_attr would still work
without problems. I can perhaps drop the NO_KERNEL_MAPPING along
with the vmap/vunmap and simplify things for those SoCs.
- Sibi
>
> Thanks,
> Robin.
>
>> drivers/remoteproc/qcom_q6v5_mss.c | 85 +++++++++++++++++++++---------
>> 1 file changed, 61 insertions(+), 24 deletions(-)
>>
>> diff --git a/drivers/remoteproc/qcom_q6v5_mss.c
>> b/drivers/remoteproc/qcom_q6v5_mss.c
>> index fddb63cffee0..8264275ecbd0 100644
>> --- a/drivers/remoteproc/qcom_q6v5_mss.c
>> +++ b/drivers/remoteproc/qcom_q6v5_mss.c
>> @@ -211,6 +211,7 @@ 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;
>> @@ -935,6 +936,7 @@ static int q6v5_mpss_init_image(struct q6v5
>> *qproc, const struct firmware *fw,
>> {
>> unsigned long dma_attrs = DMA_ATTR_FORCE_CONTIGUOUS |
>> DMA_ATTR_NO_KERNEL_MAPPING;
>> unsigned long flags = VM_DMA_COHERENT | VM_FLUSH_RESET_PERMS;
>> + void *mdata_region;
>> struct page **pages;
>> struct page *page;
>> dma_addr_t phys;
>> @@ -951,34 +953,48 @@ static int q6v5_mpss_init_image(struct q6v5
>> *qproc, const struct firmware *fw,
>> if (IS_ERR(metadata))
>> return PTR_ERR(metadata);
>> - 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;
>> - }
>> + if (qproc->mdata_phys) {
>> + mdata_region = memremap(qproc->mdata_phys, size, MEMREMAP_WC);
>> + if (!mdata_region) {
>> + dev_err(qproc->dev, "unable to map memory region:
>> %pa+%zx\n",
>> + &qproc->mdata_phys, size);
>> + ret = -EBUSY;
>> + goto free_dma_attrs;
>> + }
>> - count = PAGE_ALIGN(size) >> PAGE_SHIFT;
>> - pages = kmalloc_array(count, sizeof(struct page *), GFP_KERNEL);
>> - if (!pages) {
>> - ret = -ENOMEM;
>> - goto free_dma_attrs;
>> - }
>> + memcpy(mdata_region, metadata, size);
>> + memunmap(mdata_region);
>> + phys = qproc->mdata_phys;
>> + } else {
>> + 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;
>> + }
>> - for (i = 0; i < count; i++)
>> - pages[i] = nth_page(page, i);
>> + count = PAGE_ALIGN(size) >> PAGE_SHIFT;
>> + pages = kmalloc_array(count, sizeof(struct page *), GFP_KERNEL);
>> + if (!pages) {
>> + ret = -ENOMEM;
>> + goto free_dma_attrs;
>> + }
>> - 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;
>> - }
>> + for (i = 0; i < count; i++)
>> + pages[i] = nth_page(page, i);
>> - memcpy(vaddr, metadata, size);
>> + 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;
>> + }
>> - vunmap(vaddr);
>> + memcpy(vaddr, metadata, size);
>> +
>> + vunmap(vaddr);
>> + }
>> /* Hypervisor mapping to access metadata by modem */
>> mdata_perm = BIT(QCOM_SCM_VMID_HLOS);
>> @@ -1008,7 +1024,8 @@ 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, page, phys, dma_attrs);
>> + if (!qproc->mdata_phys)
>> + dma_free_attrs(qproc->dev, size, page, phys, dma_attrs);
>> kfree(metadata);
>> return ret < 0 ? ret : 0;
>> @@ -1882,6 +1899,26 @@ 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;
>> }
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