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

Lorenzo Pieralisi
2021-08-05T16:03:29Z

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_ ?

Thanks,
Lorenzo

> +
> + 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