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

Robin Murphy
2021-10-08T12:49:08Z

On 2021-08-05 09:07, Shameer Kolothum wrote:
> Add support for parsing RMR node information from ACPI.
>
> Find the associated streamid and smmu node info from the
> RMR node and populate a linked list with RMR memory
> descriptors.
>
> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
> ---
> drivers/acpi/arm64/iort.c | 134 +++++++++++++++++++++++++++++++++++++-
> 1 file changed, 133 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
> index 3b23fb775ac4..d76ba46ebe67 100644
> --- a/drivers/acpi/arm64/iort.c
> +++ b/drivers/acpi/arm64/iort.c
> @@ -40,6 +40,8 @@ struct iort_fwnode {
> static LIST_HEAD(iort_fwnode_list);
> static DEFINE_SPINLOCK(iort_fwnode_lock);
>
> +static LIST_HEAD(iort_rmr_list); /* list of RMR regions from ACPI */
> +
> /**
> * iort_set_fwnode() - Create iort_fwnode and use it to register
> * iommu data in the iort_fwnode_list
> @@ -393,7 +395,8 @@ static struct acpi_iort_node *iort_node_get_id(struct acpi_iort_node *node,
> if (node->type == ACPI_IORT_NODE_NAMED_COMPONENT ||
> node->type == ACPI_IORT_NODE_PCI_ROOT_COMPLEX ||
> node->type == ACPI_IORT_NODE_SMMU_V3 ||
> - node->type == ACPI_IORT_NODE_PMCG) {
> + node->type == ACPI_IORT_NODE_PMCG ||
> + node->type == ACPI_IORT_NODE_RMR) {
> *id_out = map->output_base;
> return parent;
> }
> @@ -1566,6 +1569,134 @@ static void __init iort_enable_acs(struct acpi_iort_node *iort_node)
> #else
> static inline void iort_enable_acs(struct acpi_iort_node *iort_node) { }
> #endif
> +static void iort_rmr_desc_check_overlap(struct acpi_iort_rmr_desc *desc, u32 count)
> +{
> + int i, j;
> +
> + for (i = 0; i < count; i++) {
> + u64 end, start = desc[i].base_address, length = desc[i].length;
> +
> + end = start + length - 1;
> +
> + /* Check for address overlap */
> + for (j = i + 1; j < count; j++) {
> + u64 e_start = desc[j].base_address;
> + u64 e_end = e_start + desc[j].length - 1;
> +
> + if (start <= e_end && end >= e_start)
> + pr_err(FW_BUG "RMR descriptor[0x%llx - 0x%llx] overlaps, continue anyway\n",
> + start, end);
> + }
> + }
> +}
> +
> +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;
> + }

I'm not sure we ever got a definitive answer to this - does DPAA2
actually go wrong if we use IOMMU_MMIO here? I'd still much prefer to
make the fewest possible assumptions, since at this point it's basically
just a stop-gap until we can fix the spec. It's become clear that we
can't reliably rely on guessing attributes, so I'm not too fussed about
theoretical cases that currently don't work (due to complete lack of RMR
support) continuing to not work for the moment, as long as we can make
the real-world cases we actually have work at all. Anything which only
affects performance I'd rather leave until firmware can tell us what to do.

> + 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();

I guess initcall ordering vs. driver registration probably covers it up,
but for the sake of cleanliness I'd rather make sure the RMRs are fully
discovered *before* we create the SMMU devices that we expect to start
consuming them.

Robin.

> }
>
> #ifdef CONFIG_ZONE_DMA