Re: [PATCH v7 2/9] ACPI/IORT: Add support for RMR node parsing

Laurentiu Tudor
2021-08-05T18:37:31Z

On 8/5/2021 7:03 PM, Lorenzo Pieralisi wrote:
> On Thu, Aug 05, 2021 at 09:07:17AM +0100, Shameer Kolothum wrote:
>
> [...]
>
>> +static void __init iort_node_get_rmr_info(struct acpi_iort_node *iort_node)
>> +{
>> + struct acpi_iort_node *smmu;
>> + struct acpi_iort_rmr *rmr;
>> + struct acpi_iort_rmr_desc *rmr_desc;
>> + u32 map_count = iort_node->mapping_count;
>> + u32 sid;
>> + int i;
>> +
>> + if (!iort_node->mapping_offset || map_count != 1) {
>> + pr_err(FW_BUG "Invalid ID mapping, skipping RMR node %p\n",
>> + iort_node);
>> + return;
>> + }
>> +
>> + /* Retrieve associated smmu and stream id */
>> + smmu = iort_node_get_id(iort_node, &sid, 0);
>> + if (!smmu) {
>> + pr_err(FW_BUG "Invalid SMMU reference, skipping RMR node %p\n",
>> + iort_node);
>> + return;
>> + }
>> +
>> + /* Retrieve RMR data */
>> + rmr = (struct acpi_iort_rmr *)iort_node->node_data;
>> + if (!rmr->rmr_offset || !rmr->rmr_count) {
>> + pr_err(FW_BUG "Invalid RMR descriptor array, skipping RMR node %p\n",
>> + iort_node);
>> + return;
>> + }
>> +
>> + rmr_desc = ACPI_ADD_PTR(struct acpi_iort_rmr_desc, iort_node,
>> + rmr->rmr_offset);
>> +
>> + iort_rmr_desc_check_overlap(rmr_desc, rmr->rmr_count);
>> +
>> + for (i = 0; i < rmr->rmr_count; i++, rmr_desc++) {
>> + struct iommu_resv_region *region;
>> + enum iommu_resv_type type;
>> + int prot = IOMMU_READ | IOMMU_WRITE;
>> + u64 addr = rmr_desc->base_address, size = rmr_desc->length;
>> +
>> + if (!IS_ALIGNED(addr, SZ_64K) || !IS_ALIGNED(size, SZ_64K)) {
>> + /* PAGE align base addr and size */
>> + addr &= PAGE_MASK;
>> + size = PAGE_ALIGN(size + offset_in_page(rmr_desc->base_address));
>> +
>> + pr_err(FW_BUG "RMR descriptor[0x%llx - 0x%llx] not aligned to 64K, continue with [0x%llx - 0x%llx]\n",
>> + rmr_desc->base_address,
>> + rmr_desc->base_address + rmr_desc->length - 1,
>> + addr, addr + size - 1);
>> + }
>> + if (rmr->flags & IOMMU_RMR_REMAP_PERMITTED) {
>> + type = IOMMU_RESV_DIRECT_RELAXABLE;
>> + /*
>> + * Set IOMMU_CACHE as IOMMU_RESV_DIRECT_RELAXABLE is
>> + * normally used for allocated system memory that is
>> + * then used for device specific reserved regions.
>> + */
>> + prot |= IOMMU_CACHE;
>> + } else {
>> + type = IOMMU_RESV_DIRECT;
>> + /*
>> + * Set IOMMU_MMIO as IOMMU_RESV_DIRECT is normally used
>> + * for device memory like MSI doorbell.
>> + */
>> + prot |= IOMMU_MMIO;
>> + }
>
> On the prot value assignment based on the remapping flag, I'd like to
> hear Robin/Joerg's opinion, I'd avoid being in a situation where
> "normally" this would work but then we have to quirk it.
>
> Is this a valid assumption _always_ ?

I think we enable quite a bit of platforms with this assumption, so IMHO
it's a fair compromise for now. As per Jon's comment and oob
discussions, in the long run the spec should probably be updated to
include a way of explicitly specifying memory attributes.

---
Thanks & Best Regards, Laurentiu

>
>> +
>> + region = iommu_alloc_resv_region(addr, size, prot, type);
>> + if (region) {
>> + region->fw_data.rmr.flags = rmr->flags;
>> + region->fw_data.rmr.sid = sid;
>> + region->fw_data.rmr.smmu = smmu;
>> + list_add_tail(&region->list, &iort_rmr_list);
>> + }
>> + }
>> +}
>> +
>> +static void __init iort_parse_rmr(void)
>> +{
>> + struct acpi_iort_node *iort_node, *iort_end;
>> + struct acpi_table_iort *iort;
>> + int i;
>> +
>> + if (iort_table->revision < 3)
>> + return;
>> +
>> + iort = (struct acpi_table_iort *)iort_table;
>> +
>> + iort_node = ACPI_ADD_PTR(struct acpi_iort_node, iort,
>> + iort->node_offset);
>> + iort_end = ACPI_ADD_PTR(struct acpi_iort_node, iort,
>> + iort_table->length);
>> +
>> + for (i = 0; i < iort->node_count; i++) {
>> + if (WARN_TAINT(iort_node >= iort_end, TAINT_FIRMWARE_WORKAROUND,
>> + "IORT node pointer overflows, bad table!\n"))
>> + return;
>> +
>> + if (iort_node->type == ACPI_IORT_NODE_RMR)
>> + iort_node_get_rmr_info(iort_node);
>> +
>> + iort_node = ACPI_ADD_PTR(struct acpi_iort_node, iort_node,
>> + iort_node->length);
>> + }
>> +}
>>
>> static void __init iort_init_platform_devices(void)
>> {
>> @@ -1636,6 +1767,7 @@ void __init acpi_iort_init(void)
>> }
>>
>> iort_init_platform_devices();
>> + iort_parse_rmr();
>> }
>>
>> #ifdef CONFIG_ZONE_DMA
>> --
>> 2.17.1
>>
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