On Mon, Apr 28, 2025 at 12:07:50PM +0100, Alireza Sanaee wrote:
> Specify which layer (core/cluster/socket) caches found at in the CPU
> topology. Updating cache topology to device tree (spec v0.4).
> Example:
>
> Here, 2 sockets (packages), and 2 clusters, 4 cores and 2 threads
> created, in aggregate 2*2*4*2 logical cores. In the smp-cache object,
> cores will have l1d and l1i. However, extending this is not difficult).
> The clusters will share a unified l2 level cache, and finally sockets
> will share l3. In this patch, threads will share l1 caches by default,
> but this can be adjusted if case required.
>
> Currently only three levels of caches are supported. The patch does not
> allow partial declaration of caches. In another word, all caches must be
> defined or caches must be skipped.
>
> ./qemu-system-aarch64 \
> -machine virt,\
> smp-cache.0.cache=l1i,smp-cache.0.topology=core,\
> smp-cache.1.cache=l1d,smp-cache.1.topology=core,\
> smp-cache.2.cache=l2,smp-cache.2.topology=cluster,\
> smp-cache.3.cache=l3,smp-cache.3.topology=socket\
> -cpu max \
> -m 2048 \
> -smp sockets=2,clusters=2,cores=4,threads=1 \
> -kernel ./Image.gz \
> -append "console=ttyAMA0 root=/dev/ram rdinit=/init acpi=force" \
> -initrd rootfs.cpio.gz \
> -bios ./edk2-aarch64-code.fd \
> -nographic
>
> For instance, following device tree will be generated for a scenario
> where we have 2 sockets, 2 clusters, 2 cores and 2 threads, in total 16
> PEs. L1i and L1d are private to each thread, and l2 and l3 are shared at
> socket level as an example.
>
> Limitation: SMT cores cannot share L1 cache for now. This
> problem does not exist in PPTT tables.
>
> Signed-off-by: Alireza Sanaee <alireza.san...@huawei.com>
> Co-developed-by: Jonathan Cameron <jonathan.came...@huawei.com>
> Signed-off-by: Jonathan Cameron <jonathan.came...@huawei.com>
> ---
> hw/arm/virt.c | 343 ++++++++++++++++++++++++++++++++++++++++++
> hw/cpu/core.c | 92 +++++++++++
> include/hw/arm/virt.h | 4 +
> include/hw/cpu/core.h | 25 +++
> 4 files changed, 464 insertions(+)
>
> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> index a96452f17a48..ece8203e9f0b 100644
> --- a/hw/arm/virt.c
> +++ b/hw/arm/virt.c
> @@ -238,6 +238,132 @@ static const int a15irqmap[] = {
> [VIRT_PLATFORM_BUS] = 112, /* ...to 112 + PLATFORM_BUS_NUM_IRQS -1 */
> };
>
> +unsigned int virt_get_caches(const VirtMachineState *vms,
> + PPTTCPUCaches *caches)
pass an array size so we can assert on OOB at least.
> +{
> + ARMCPU *armcpu = ARM_CPU(qemu_get_cpu(0)); /* assume homogeneous CPUs */
> + bool ccidx = cpu_isar_feature(any_ccidx, armcpu);
> + unsigned int num_cache, i;
> + int level_instr = 1, level_data = 1;
> +
> + for (i = 0, num_cache = 0; i < CPU_MAX_CACHES; i++, num_cache++) {
> + int type = (armcpu->clidr >> (3 * i)) & 7;
> + int bank_index;
> + int level;
> + PPTTCPUCacheType cache_type;
> +
> + if (type == 0) {
> + break;
> + }
> +
> + switch (type) {
> + case 1:
> + cache_type = INSTRUCTION;
> + level = level_instr;
> + break;
> + case 2:
> + cache_type = DATA;
> + level = level_data;
> + break;
> + case 4:
> + cache_type = UNIFIED;
> + level = level_instr > level_data ? level_instr : level_data;
> + break;
> + case 3: /* Split - Do data first */
> + cache_type = DATA;
> + level = level_data;
> + break;
> + default:
> + error_setg(&error_abort, "Unrecognized cache type");
> + return 0;
> + }
> + /*
> + * ccsidr is indexed using both the level and whether it is
> + * an instruction cache. Unified caches use the same storage
> + * as data caches.
> + */
> + bank_index = (i * 2) | ((type == 1) ? 1 : 0);
> + if (ccidx) {
> + caches[num_cache] = (PPTTCPUCaches) {
> + .type = cache_type,
> + .level = level,
> + .linesize = 1 << (FIELD_EX64(armcpu->ccsidr[bank_index],
> + CCSIDR_EL1,
> + CCIDX_LINESIZE) + 4),
> + .associativity = FIELD_EX64(armcpu->ccsidr[bank_index],
> + CCSIDR_EL1,
> + CCIDX_ASSOCIATIVITY) + 1,
> + .sets = FIELD_EX64(armcpu->ccsidr[bank_index], CCSIDR_EL1,
> + CCIDX_NUMSETS) + 1,
> + };
> + } else {
> + caches[num_cache] = (PPTTCPUCaches) {
> + .type = cache_type,
> + .level = level,
> + .linesize = 1 << (FIELD_EX64(armcpu->ccsidr[bank_index],
> + CCSIDR_EL1, LINESIZE) + 4),
> + .associativity = FIELD_EX64(armcpu->ccsidr[bank_index],
> + CCSIDR_EL1,
> + ASSOCIATIVITY) + 1,
> + .sets = FIELD_EX64(armcpu->ccsidr[bank_index], CCSIDR_EL1,
> + NUMSETS) + 1,
> + };
> + }
> + caches[num_cache].size = caches[num_cache].associativity *
> + caches[num_cache].sets * caches[num_cache].linesize;
> +
> + /* Break one 'split' entry up into two records */
> + if (type == 3) {
> + num_cache++;
> + bank_index = (i * 2) | 1;
> + if (ccidx) {
> + /* Instruction cache: bottom bit set when reading banked reg
> */
> + caches[num_cache] = (PPTTCPUCaches) {
> + .type = INSTRUCTION,
> + .level = level_instr,
> + .linesize = 1 << (FIELD_EX64(armcpu->ccsidr[bank_index],
> + CCSIDR_EL1,
> + CCIDX_LINESIZE) + 4),
> + .associativity = FIELD_EX64(armcpu->ccsidr[bank_index],
> + CCSIDR_EL1,
> + CCIDX_ASSOCIATIVITY) + 1,
> + .sets = FIELD_EX64(armcpu->ccsidr[bank_index],
> CCSIDR_EL1,
> + CCIDX_NUMSETS) + 1,
> + };
> + } else {
> + caches[num_cache] = (PPTTCPUCaches) {
> + .type = INSTRUCTION,
> + .level = level_instr,
> + .linesize = 1 << (FIELD_EX64(armcpu->ccsidr[bank_index],
> + CCSIDR_EL1, LINESIZE) + 4),
> + .associativity = FIELD_EX64(armcpu->ccsidr[bank_index],
> + CCSIDR_EL1,
> + ASSOCIATIVITY) + 1,
> + .sets = FIELD_EX64(armcpu->ccsidr[bank_index],
> CCSIDR_EL1,
> + NUMSETS) + 1,
> + };
> + }
> + caches[num_cache].size = caches[num_cache].associativity *
> + caches[num_cache].sets * caches[num_cache].linesize;
> + }
> + switch (type) {
> + case 1:
> + level_instr++;
> + break;
> + case 2:
> + level_data++;
> + break;
> + case 3:
> + case 4:
> + level_instr++;
> + level_data++;
> + break;
> + }
> + }
> +
> + return num_cache;
> +}
> +
> static void create_randomness(MachineState *ms, const char *node)
> {
> struct {
> @@ -421,13 +547,96 @@ static void fdt_add_timer_nodes(const VirtMachineState
> *vms)
> }
> }
>
> +static void add_cache_node(void *fdt, char * nodepath, PPTTCPUCaches cache,
> + uint32_t *next_level) {
coding style violation
> + /* Assume L2/3 are unified caches. */
> +
> + uint32_t phandle;
> +
> + qemu_fdt_add_path(fdt, nodepath);
> + phandle = qemu_fdt_alloc_phandle(fdt);
> + qemu_fdt_setprop_cell(fdt, nodepath, "phandle", phandle);
> + qemu_fdt_setprop_cell(fdt, nodepath, "cache-level", cache.level);
> + qemu_fdt_setprop_cell(fdt, nodepath, "cache-size", cache.size);
> + qemu_fdt_setprop_cell(fdt, nodepath, "cache-block-size", cache.linesize);
> + qemu_fdt_setprop_cell(fdt, nodepath, "cache-sets", cache.sets);
> + qemu_fdt_setprop(fdt, nodepath, "cache-unified", NULL, 0);
> + qemu_fdt_setprop_string(fdt, nodepath, "compatible", "cache");
> + if (cache.level != 3) {
> + /* top level cache doesn't have next-level-cache property */
> + qemu_fdt_setprop_cell(fdt, nodepath, "next-level-cache",
> *next_level);
> + }
> +
> + *next_level = phandle;
> +}
> +
> +static bool add_cpu_cache_hierarchy(void *fdt, PPTTCPUCaches* cache,
> + uint32_t cache_cnt,
> + uint32_t top_level,
> + uint32_t bottom_level,
> + uint32_t cpu_id,
> + uint32_t *next_level) {
> + bool found_cache = false;
> + char *nodepath;
> +
> + for (int level = top_level; level >= bottom_level; level--) {
> + for (int i = 0; i < cache_cnt; i++) {
> + if (i != level) {
> + continue;
> + }
> +
> + nodepath = g_strdup_printf("/cpus/cpu@%d/l%d-cache",
> + cpu_id, level);
> + add_cache_node(fdt, nodepath, cache[i], next_level);
> + found_cache = true;
> + g_free(nodepath);
> +
> + }
> + }
> +
> + return found_cache;
> +}
> +
> +static void set_cache_properties(void *fdt, const char *nodename,
> + const char *prefix, PPTTCPUCaches cache)
> +{
> + char prop_name[64];
> +
> + snprintf(prop_name, sizeof(prop_name), "%s-block-size", prefix);
> + qemu_fdt_setprop_cell(fdt, nodename, prop_name, cache.linesize);
> +
> + snprintf(prop_name, sizeof(prop_name), "%s-size", prefix);
> + qemu_fdt_setprop_cell(fdt, nodename, prop_name, cache.size);
> +
> + snprintf(prop_name, sizeof(prop_name), "%s-sets", prefix);
> + qemu_fdt_setprop_cell(fdt, nodename, prop_name, cache.sets);
> +}
> +
> static void fdt_add_cpu_nodes(const VirtMachineState *vms)
> {
> int cpu;
> int addr_cells = 1;
> const MachineState *ms = MACHINE(vms);
> + const MachineClass *mc = MACHINE_GET_CLASS(ms);
> const VirtMachineClass *vmc = VIRT_MACHINE_GET_CLASS(vms);
> int smp_cpus = ms->smp.cpus;
> + int socket_id, cluster_id, core_id;
> + uint32_t next_level = 0;
> + uint32_t socket_offset = 0, cluster_offset = 0, core_offset = 0;
> + int last_socket = -1, last_cluster = -1, last_core = -1;
> + int top_node = 3, top_cluster = 3, top_core = 3;
> + int bottom_node = 3, bottom_cluster = 3, bottom_core = 3;
do these one var at a time.
> + unsigned int num_cache;
> + PPTTCPUCaches caches[16];
why 16?
> + bool cache_created = false;
> +
> + num_cache = virt_get_caches(vms, caches);
> +
> + if (mc->smp_props.has_caches &&
> + partial_cache_description(ms, caches, num_cache)) {
> + error_setg(&error_fatal, "Missing cache description");
> + return;
> + }
>
> /*
> * See Linux Documentation/devicetree/bindings/arm/cpus.yaml
> @@ -456,9 +665,14 @@ static void fdt_add_cpu_nodes(const VirtMachineState
> *vms)
> qemu_fdt_setprop_cell(ms->fdt, "/cpus", "#size-cells", 0x0);
>
> for (cpu = smp_cpus - 1; cpu >= 0; cpu--) {
> + socket_id = cpu / (ms->smp.clusters * ms->smp.cores *
> ms->smp.threads);
> + cluster_id = cpu / (ms->smp.cores * ms->smp.threads) %
> ms->smp.clusters;
> + core_id = cpu / (ms->smp.threads) % ms->smp.cores;
> +
> char *nodename = g_strdup_printf("/cpus/cpu@%d", cpu);
> ARMCPU *armcpu = ARM_CPU(qemu_get_cpu(cpu));
> CPUState *cs = CPU(armcpu);
> + const char *prefix = NULL;
>
> qemu_fdt_add_subnode(ms->fdt, nodename);
> qemu_fdt_setprop_string(ms->fdt, nodename, "device_type", "cpu");
> @@ -488,6 +702,130 @@ static void fdt_add_cpu_nodes(const VirtMachineState
> *vms)
> qemu_fdt_alloc_phandle(ms->fdt));
> }
>
> + if (!vmc->no_cpu_topology && num_cache) {
> + for (uint8_t i = 0; i < num_cache; i++) {
> + /* only level 1 in the CPU entry */
> + if (caches[i].level > 1) {
> + continue;
> + }
> +
> + if (caches[i].type == INSTRUCTION) {
> + prefix = "i-cache";
> + } else if (caches[i].type == DATA) {
> + prefix = "d-cache";
> + } else if (caches[i].type == UNIFIED) {
> + error_setg(&error_fatal,
> + "Unified type is not implemented at level %d",
> + caches[i].level);
> + return;
> + } else {
> + error_setg(&error_fatal, "Undefined cache type");
> + return;
> + }
> +
> + set_cache_properties(ms->fdt, nodename, prefix, caches[i]);
> + }
> + }
> +
> + if (socket_id != last_socket) {
> + bottom_node = top_node;
> + /* this assumes socket as the highest topological level */
> + socket_offset = 0;
> + cluster_offset = 0;
> + if (cache_described_at(ms, CPU_TOPOLOGY_LEVEL_SOCKET) &&
> + find_the_lowest_level_cache_defined_at_level(ms,
> + &bottom_node,
> + CPU_TOPOLOGY_LEVEL_SOCKET)) {
> +
> + if (bottom_node == 1) {
> + error_report(
> + "Cannot share L1 at socket_id %d. DT limiation on "
> + "sharing at cache level = 1",
> + socket_id);
> + }
> +
> + cache_created = add_cpu_cache_hierarchy(ms->fdt, caches,
> + num_cache,
> + top_node,
> + bottom_node, cpu,
> + &socket_offset);
> +
> + if (!cache_created) {
> + error_setg(&error_fatal,
> + "Socket: No caches at levels %d-%d",
> + top_node, bottom_node);
> + return;
> + }
> +
> + top_cluster = bottom_node - 1;
> + }
> +
> + last_socket = socket_id;
> + }
> +
> + if (cluster_id != last_cluster) {
> + bottom_cluster = top_cluster;
> + cluster_offset = socket_offset;
> + core_offset = 0;
> + if (cache_described_at(ms, CPU_TOPOLOGY_LEVEL_CLUSTER) &&
> + find_the_lowest_level_cache_defined_at_level(ms,
> + &bottom_cluster,
> + CPU_TOPOLOGY_LEVEL_CLUSTER)) {
> +
> + cache_created = add_cpu_cache_hierarchy(ms->fdt, caches,
> + num_cache,
> + top_cluster,
> + bottom_cluster, cpu,
> + &cluster_offset);
> + if (bottom_cluster == 1) {
> + error_report(
> + "Cannot share L1 at socket_id %d, cluster_id %d. "
> + "DT limitation on sharing at cache level = 1.",
> + socket_id, cluster_id);
> + }
> +
> + if (!cache_created) {
> + error_setg(&error_fatal,
> + "Cluster: No caches at levels %d-%d",
> + top_cluster, bottom_cluster);
> + return;
> + }
> +
> + top_core = bottom_cluster - 1;
> + } else if (top_cluster == bottom_node - 1) {
> + top_core = bottom_node - 1;
> + }
> +
> + last_cluster = cluster_id;
> + }
> +
> + if (core_id != last_core) {
> + bottom_core = top_core;
> + core_offset = cluster_offset;
> + if (cache_described_at(ms, CPU_TOPOLOGY_LEVEL_CORE) &&
> + find_the_lowest_level_cache_defined_at_level(ms,
> + &bottom_core,
> + CPU_TOPOLOGY_LEVEL_CORE)) {
> +
> + if (bottom_core == 1) {
> + bottom_core++;
> + }
> +
> + cache_created = add_cpu_cache_hierarchy(ms->fdt,
> + caches,
> + num_cache,
> + top_core,
> + bottom_core, cpu,
> + &core_offset);
> + }
> +
> + last_core = core_id;
> + }
> +
> + next_level = core_offset;
> + qemu_fdt_setprop_cell(ms->fdt, nodename, "next-level-cache",
> + next_level);
> +
> g_free(nodename);
> }
>
> @@ -3193,6 +3531,11 @@ static void virt_machine_class_init(ObjectClass *oc,
> void *data)
> hc->unplug = virt_machine_device_unplug_cb;
> mc->nvdimm_supported = true;
> mc->smp_props.clusters_supported = true;
> + /* Supported caches */
> + mc->smp_props.cache_supported[CACHE_LEVEL_AND_TYPE_L1D] = true;
> + mc->smp_props.cache_supported[CACHE_LEVEL_AND_TYPE_L1I] = true;
> + mc->smp_props.cache_supported[CACHE_LEVEL_AND_TYPE_L2] = true;
> + mc->smp_props.cache_supported[CACHE_LEVEL_AND_TYPE_L3] = true;
> mc->auto_enable_numa_with_memhp = true;
> mc->auto_enable_numa_with_memdev = true;
> /* platform instead of architectural choice */
> diff --git a/hw/cpu/core.c b/hw/cpu/core.c
> index 495a5c30ffe1..3adfc3ca0001 100644
> --- a/hw/cpu/core.c
> +++ b/hw/cpu/core.c
> @@ -102,4 +102,96 @@ static void cpu_core_register_types(void)
> type_register_static(&cpu_core_type_info);
> }
>
> +bool cache_described_at(const MachineState *ms, CpuTopologyLevel level)
> +{
> + if (machine_get_cache_topo_level(ms, CACHE_LEVEL_AND_TYPE_L3) == level ||
> + machine_get_cache_topo_level(ms, CACHE_LEVEL_AND_TYPE_L2) == level ||
> + machine_get_cache_topo_level(ms, CACHE_LEVEL_AND_TYPE_L1I) == level
> ||
> + machine_get_cache_topo_level(ms, CACHE_LEVEL_AND_TYPE_L1D) == level)
> {
> + return true;
> + }
> + return false;
> +}
> +
> +int partial_cache_description(const MachineState *ms, PPTTCPUCaches *caches,
> + int num_caches)
> +{
> + int level, c;
> +
> + for (level = 1; level < num_caches; level++) {
> + for (c = 0; c < num_caches; c++) {
> + if (caches[c].level != level) {
> + continue;
> + }
> +
> + switch (level) {
> + case 1:
> + /*
> + * L1 cache is assumed to have both L1I and L1D available.
> + * Technically both need to be checked.
> + */
> + if (machine_get_cache_topo_level(ms,
> + CACHE_LEVEL_AND_TYPE_L1I) ==
> + CPU_TOPOLOGY_LEVEL_DEFAULT) {
> + return level;
> + }
> + break;
> + case 2:
> + if (machine_get_cache_topo_level(ms,
> CACHE_LEVEL_AND_TYPE_L2) ==
> + CPU_TOPOLOGY_LEVEL_DEFAULT) {
> + return level;
> + }
> + break;
> + case 3:
> + if (machine_get_cache_topo_level(ms,
> CACHE_LEVEL_AND_TYPE_L3) ==
> + CPU_TOPOLOGY_LEVEL_DEFAULT) {
> + return level;
> + }
> + break;
> + }
> + }
> + }
> +
> + return 0;
> +}
> +
> +/*
> + * This function assumes l3 and l2 have unified cache and l1 is split l1d
> + * and l1i, and further prepares the lowest cache level for a topology
> + * level. The info will be fed to build_caches to create caches at the
> + * right level.
> + */
> +bool find_the_lowest_level_cache_defined_at_level(const MachineState *ms,
> + int *level_found,
> + CpuTopologyLevel
> topo_level) {
> +
> + CpuTopologyLevel level;
> +
> + level = machine_get_cache_topo_level(ms, CACHE_LEVEL_AND_TYPE_L1I);
> + if (level == topo_level) {
> + *level_found = 1;
> + return true;
> + }
> +
> + level = machine_get_cache_topo_level(ms, CACHE_LEVEL_AND_TYPE_L1D);
> + if (level == topo_level) {
> + *level_found = 1;
> + return true;
> + }
> +
> + level = machine_get_cache_topo_level(ms, CACHE_LEVEL_AND_TYPE_L2);
> + if (level == topo_level) {
> + *level_found = 2;
> + return true;
> + }
> +
> + level = machine_get_cache_topo_level(ms, CACHE_LEVEL_AND_TYPE_L3);
> + if (level == topo_level) {
> + *level_found = 3;
> + return true;
> + }
> +
> + return false;
> +}
> +
> type_init(cpu_core_register_types)
> diff --git a/include/hw/arm/virt.h b/include/hw/arm/virt.h
> index c8e94e6aedc9..68ff99d6806d 100644
> --- a/include/hw/arm/virt.h
> +++ b/include/hw/arm/virt.h
> @@ -39,6 +39,7 @@
> #include "system/kvm.h"
> #include "hw/intc/arm_gicv3_common.h"
> #include "qom/object.h"
> +#include "hw/cpu/core.h"
>
> #define NUM_GICV2M_SPIS 64
> #define NUM_VIRTIO_TRANSPORTS 32
> @@ -50,6 +51,8 @@
> /* GPIO pins */
> #define GPIO_PIN_POWER_BUTTON 3
>
> +#define CPU_MAX_CACHES 16
> +
> enum {
> VIRT_FLASH,
> VIRT_MEM,
> @@ -189,6 +192,7 @@ OBJECT_DECLARE_TYPE(VirtMachineState, VirtMachineClass,
> VIRT_MACHINE)
>
> void virt_acpi_setup(VirtMachineState *vms);
> bool virt_is_acpi_enabled(VirtMachineState *vms);
> +unsigned int virt_get_caches(const VirtMachineState *vms, PPTTCPUCaches
> *caches);
>
> /* Return number of redistributors that fit in the specified region */
> static uint32_t virt_redist_capacity(VirtMachineState *vms, int region)
> diff --git a/include/hw/cpu/core.h b/include/hw/cpu/core.h
> index 98ab91647eb2..a90b708b835b 100644
> --- a/include/hw/cpu/core.h
> +++ b/include/hw/cpu/core.h
> @@ -25,6 +25,31 @@ struct CPUCore {
> int nr_threads;
> };
>
> +typedef enum CPUCacheType {
> + DATA,
> + INSTRUCTION,
> + UNIFIED,
> +} PPTTCPUCacheType;
Given specific values matter, you should specify them.
Also, please prefix names sensibly and consistently:
CPUCoreCacheType CPU_CORE_DATA and so on.
> +
> +typedef struct PPTTCPUCaches {
> + PPTTCPUCacheType type;
> + uint32_t sets;
> + uint32_t size;
> + uint32_t level;
> + uint16_t linesize;
> + uint8_t attributes; /* write policy: 0x0 write back, 0x1 write through */
> + uint8_t associativity;
> +} PPTTCPUCaches;
> +
> +int partial_cache_description(const MachineState *ms, PPTTCPUCaches *caches,
> + int num_caches);
> +
> +bool cache_described_at(const MachineState *ms, CpuTopologyLevel level);
> +
> +bool find_the_lowest_level_cache_defined_at_level(const MachineState *ms,
> + int *level_found,
> + CpuTopologyLevel
> topo_level);
> +
> /* Note: topology field names need to be kept in sync with
> * 'CpuInstanceProperties' */
same here, prefix everything with cpu_core CPUCore etc.
> --
> 2.34.1
