From 1c41eaa5fe03cbe9f60edb8f0414c1ad6d7fd786 Mon Sep 17 00:00:00 2001 From: Gustavo Romero Date: Tue, 1 Jul 2025 15:08:30 +0100 Subject: [PATCH] hw/arm/virt-acpi-build: Factor out create_its_idmaps Factor out a new function, create_its_idmaps(), from the current build_iort code. Add proper comments to it clarifying how the ID ranges that go directly to the ITS Group node are computed based on the ones that are directed to the SMMU node. Suggested-by: Eric Auger Signed-off-by: Gustavo Romero Message-id: 20250628195722.977078-6-gustavo.romero@linaro.org [PMM: drop hardcoded tabs] Signed-off-by: Peter Maydell --- hw/arm/virt-acpi-build.c | 61 ++++++++++++++++++++++++++-------------- 1 file changed, 40 insertions(+), 21 deletions(-) diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c index e9cd3fb3511..5886192fe3f 100644 --- a/hw/arm/virt-acpi-build.c +++ b/hw/arm/virt-acpi-build.c @@ -266,6 +266,43 @@ static int iort_idmap_compare(gconstpointer a, gconstpointer b) return idmap_a->input_base - idmap_b->input_base; } +/* Compute ID ranges (RIDs) from RC that are directed to the ITS Group node */ +static void create_its_idmaps(GArray *its_idmaps, GArray *smmu_idmaps) +{ + AcpiIortIdMapping *idmap; + AcpiIortIdMapping next_range = {0}; + + /* + * Based on the RID ranges that are directed to the SMMU, determine the + * bypassed RID ranges, i.e., the ones that are directed to the ITS Group + * node and do not pass through the SMMU, by subtracting the SMMU-bound + * ranges from the full RID range (0x0000–0xFFFF). + */ + for (int i = 0; i < smmu_idmaps->len; i++) { + idmap = &g_array_index(smmu_idmaps, AcpiIortIdMapping, i); + + if (next_range.input_base < idmap->input_base) { + next_range.id_count = idmap->input_base - next_range.input_base; + g_array_append_val(its_idmaps, next_range); + } + + next_range.input_base = idmap->input_base + idmap->id_count; + } + + /* + * Append the last RC -> ITS ID mapping. + * + * RIDs are 16-bit, according to the PCI Express 2.0 Base Specification, rev + * 0.9, section 2.2.6.2, "Transaction Descriptor - Transaction ID Field", + * hence the end of the range is 0x10000. + */ + if (next_range.input_base < 0x10000) { + next_range.id_count = 0x10000 - next_range.input_base; + g_array_append_val(its_idmaps, next_range); + } +} + + /* * Input Output Remapping Table (IORT) * Conforms to "IO Remapping Table System Software on ARM Platforms", @@ -276,7 +313,6 @@ build_iort(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms) { int i, nb_nodes, rc_mapping_count; size_t node_size, smmu_offset = 0; - AcpiIortIdMapping *idmap; uint32_t id = 0; GArray *smmu_idmaps = g_array_new(false, true, sizeof(AcpiIortIdMapping)); GArray *its_idmaps = g_array_new(false, true, sizeof(AcpiIortIdMapping)); @@ -287,8 +323,6 @@ build_iort(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms) acpi_table_begin(&table, table_data); if (vms->iommu == VIRT_IOMMU_SMMUV3) { - AcpiIortIdMapping next_range = {0}; - object_child_foreach_recursive(object_get_root(), iort_host_bridges, smmu_idmaps); @@ -296,25 +330,10 @@ build_iort(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms) g_array_sort(smmu_idmaps, iort_idmap_compare); /* - * Split the whole RIDs by mapping from RC to SMMU, - * build the ID mapping from RC to ITS directly. + * Knowing the ID ranges from the RC to the SMMU, it's possible to + * determine the ID ranges from RC that are directed to the ITS. */ - for (i = 0; i < smmu_idmaps->len; i++) { - idmap = &g_array_index(smmu_idmaps, AcpiIortIdMapping, i); - - if (next_range.input_base < idmap->input_base) { - next_range.id_count = idmap->input_base - next_range.input_base; - g_array_append_val(its_idmaps, next_range); - } - - next_range.input_base = idmap->input_base + idmap->id_count; - } - - /* Append the last RC -> ITS ID mapping */ - if (next_range.input_base < 0x10000) { - next_range.id_count = 0x10000 - next_range.input_base; - g_array_append_val(its_idmaps, next_range); - } + create_its_idmaps(its_idmaps, smmu_idmaps); nb_nodes = 3; /* RC, ITS, SMMUv3 */ rc_mapping_count = smmu_idmaps->len + its_idmaps->len; -- 2.47.2