@@ -20,6 +20,7 @@
#define BITS_PER_LONG (sizeof (unsigned long) * BITS_PER_BYTE)
#define BIT(nr) (1UL << (nr))
+#define BIT_ULL(nr) (1ULL << (nr))
#define BIT_MASK(nr) (1UL << ((nr) % BITS_PER_LONG))
#define BIT_WORD(nr) ((nr) / BITS_PER_LONG)
#define BITS_TO_LONGS(nr) DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long))
@@ -184,8 +184,13 @@ typedef struct {
#ifdef TARGET_AARCH64
# define ARM_MAX_VQ 16
+void arm_cpu_sve_finalize(ARMCPU *cpu, Error **errp);
+uint32_t arm_cpu_vq_map_next_smaller(ARMCPU *cpu, uint32_t vq);
#else
# define ARM_MAX_VQ 1
+static inline void arm_cpu_sve_finalize(ARMCPU *cpu, Error **errp) { }
+static inline uint32_t arm_cpu_vq_map_next_smaller(ARMCPU *cpu, uint32_t vq)
+{ return 0; }
#endif
typedef struct ARMVectorReg {
@@ -918,6 +923,18 @@ struct ARMCPU {
/* Used to set the maximum vector length the cpu will support. */
uint32_t sve_max_vq;
+
+ /*
+ * In sve_vq_map each set bit is a supported vector length of
+ * (bit-number + 1) * 16 bytes, i.e. each bit number + 1 is the vector
+ * length in quadwords.
+ *
+ * While processing properties during initialization, corresponding
+ * sve_vq_init bits are set for bits in sve_vq_map that have been
+ * set by properties.
+ */
+ DECLARE_BITMAP(sve_vq_map, ARM_MAX_VQ);
+ DECLARE_BITMAP(sve_vq_init, ARM_MAX_VQ);
};
void arm_cpu_post_init(Object *obj);
@@ -1837,6 +1854,8 @@ static inline int arm_feature(CPUARMState *env, int feature)
return (env->features & (1ULL << feature)) != 0;
}
+void arm_cpu_finalize_features(ARMCPU *cpu, Error **errp);
+
#if !defined(CONFIG_USER_ONLY)
/* Return true if exception levels below EL3 are in secure state,
* or would be following an exception return to that level.
@@ -1198,6 +1198,19 @@ static void arm_cpu_finalizefn(Object *obj)
#endif
}
+void arm_cpu_finalize_features(ARMCPU *cpu, Error **errp)
+{
+ Error *local_err = NULL;
+
+ if (arm_feature(&cpu->env, ARM_FEATURE_AARCH64)) {
+ arm_cpu_sve_finalize(cpu, &local_err);
+ if (local_err != NULL) {
+ error_propagate(errp, local_err);
+ return;
+ }
+ }
+}
+
static void arm_cpu_realizefn(DeviceState *dev, Error **errp)
{
CPUState *cs = CPU(dev);
@@ -1254,6 +1267,12 @@ static void arm_cpu_realizefn(DeviceState *dev, Error **errp)
return;
}
+ arm_cpu_finalize_features(cpu, &local_err);
+ if (local_err != NULL) {
+ error_propagate(errp, local_err);
+ return;
+ }
+
if (arm_feature(env, ARM_FEATURE_AARCH64) &&
cpu->has_vfp != cpu->has_neon) {
/*
@@ -256,6 +256,151 @@ static void aarch64_a72_initfn(Object *obj)
define_arm_cp_regs(cpu, cortex_a72_a57_a53_cp_reginfo);
}
+void arm_cpu_sve_finalize(ARMCPU *cpu, Error **errp)
+{
+ /*
+ * If any vector lengths are explicitly enabled with sve<N> properties,
+ * then all other lengths are implicitly disabled. If sve-max-vq is
+ * specified then it is the same as explicitly enabling all lengths
+ * up to and including the specified maximum, which means all larger
+ * lengths will be implicitly disabled. If no sve<N> properties
+ * are enabled and sve-max-vq is not specified, then all lengths not
+ * explicitly disabled will be enabled. Additionally, all power-of-two
+ * vector lengths less than the maximum enabled length will be
+ * automatically enabled and all vector lengths larger than the largest
+ * disabled power-of-two vector length will be automatically disabled.
+ * Errors are generated if the user provided input that interferes with
+ * any of the above. Finally, if SVE is not disabled, then at least one
+ * vector length must be enabled.
+ */
+ DECLARE_BITMAP(tmp, ARM_MAX_VQ);
+ uint32_t vq, max_vq = 0;
+
+ /*
+ * Process explicit sve<N> properties.
+ * From the properties, sve_vq_map<N> implies sve_vq_init<N>.
+ * Check first for any sve<N> enabled.
+ */
+ if (!bitmap_empty(cpu->sve_vq_map, ARM_MAX_VQ)) {
+ max_vq = find_last_bit(cpu->sve_vq_map, ARM_MAX_VQ) + 1;
+
+ if (cpu->sve_max_vq && max_vq > cpu->sve_max_vq) {
+ error_setg(errp, "cannot enable sve%d", max_vq * 128);
+ error_append_hint(errp, "sve%d is larger than the maximum vector "
+ "length, sve-max-vq=%d (%d bits)\n",
+ max_vq * 128, cpu->sve_max_vq,
+ cpu->sve_max_vq * 128);
+ return;
+ }
+
+ /* Propagate enabled bits down through required powers-of-two. */
+ for (vq = pow2floor(max_vq); vq >= 1; vq >>= 1) {
+ if (!test_bit(vq - 1, cpu->sve_vq_init)) {
+ set_bit(vq - 1, cpu->sve_vq_map);
+ }
+ }
+ } else if (cpu->sve_max_vq == 0) {
+ /*
+ * No explicit bits enabled, and no implicit bits from sve-max-vq.
+ */
+ if (!cpu_isar_feature(aa64_sve, cpu)) {
+ /* SVE is disabled and so are all vector lengths. Good. */
+ return;
+ }
+
+ /* Disabling a power-of-two disables all larger lengths. */
+ if (test_bit(0, cpu->sve_vq_init)) {
+ error_setg(errp, "cannot disable sve128");
+ error_append_hint(errp, "Disabling sve128 results in all vector "
+ "lengths being disabled.\n");
+ error_append_hint(errp, "With SVE enabled, at least one vector "
+ "length must be enabled.\n");
+ return;
+ }
+ for (vq = 2; vq <= ARM_MAX_VQ; vq <<= 1) {
+ if (test_bit(vq - 1, cpu->sve_vq_init)) {
+ break;
+ }
+ }
+ max_vq = vq <= ARM_MAX_VQ ? vq - 1 : ARM_MAX_VQ;
+
+ bitmap_complement(cpu->sve_vq_map, cpu->sve_vq_init, max_vq);
+ max_vq = find_last_bit(cpu->sve_vq_map, max_vq) + 1;
+ }
+
+ /*
+ * Process the sve-max-vq property.
+ * Note that we know from the above that no bit above
+ * sve-max-vq is currently set.
+ */
+ if (cpu->sve_max_vq != 0) {
+ max_vq = cpu->sve_max_vq;
+
+ if (!test_bit(max_vq - 1, cpu->sve_vq_map) &&
+ test_bit(max_vq - 1, cpu->sve_vq_init)) {
+ error_setg(errp, "cannot disable sve%d", max_vq * 128);
+ error_append_hint(errp, "The maximum vector length must be "
+ "enabled, sve-max-vq=%d (%d bits)\n",
+ max_vq, max_vq * 128);
+ return;
+ }
+
+ /* Set all bits not explicitly set within sve-max-vq. */
+ bitmap_complement(tmp, cpu->sve_vq_init, max_vq);
+ bitmap_or(cpu->sve_vq_map, cpu->sve_vq_map, tmp, max_vq);
+ }
+
+ /*
+ * We should know what max-vq is now. Also, as we're done
+ * manipulating sve-vq-map, we ensure any bits above max-vq
+ * are clear, just in case anybody looks.
+ */
+ assert(max_vq != 0);
+ bitmap_clear(cpu->sve_vq_map, max_vq, ARM_MAX_VQ - max_vq);
+
+ /* Ensure all required powers-of-two are enabled. */
+ for (vq = pow2floor(max_vq); vq >= 1; vq >>= 1) {
+ if (!test_bit(vq - 1, cpu->sve_vq_map)) {
+ error_setg(errp, "cannot disable sve%d", vq * 128);
+ error_append_hint(errp, "sve%d is required as it "
+ "is a power-of-two length smaller than "
+ "the maximum, sve%d\n",
+ vq * 128, max_vq * 128);
+ return;
+ }
+ }
+
+ /*
+ * Now that we validated all our vector lengths, the only question
+ * left to answer is if we even want SVE at all.
+ */
+ if (!cpu_isar_feature(aa64_sve, cpu)) {
+ error_setg(errp, "cannot enable sve%d", max_vq * 128);
+ error_append_hint(errp, "SVE must be enabled to enable vector "
+ "lengths.\n");
+ error_append_hint(errp, "Add sve=on to the CPU property list.\n");
+ return;
+ }
+
+ /* From now on sve_max_vq is the actual maximum supported length. */
+ cpu->sve_max_vq = max_vq;
+}
+
+uint32_t arm_cpu_vq_map_next_smaller(ARMCPU *cpu, uint32_t vq)
+{
+ uint32_t bitnum;
+
+ /*
+ * We allow vq == ARM_MAX_VQ + 1 to be input because the caller may want
+ * to find the maximum vq enabled, which may be ARM_MAX_VQ, but this
+ * function always returns the next smaller than the input.
+ */
+ assert(vq && vq <= ARM_MAX_VQ + 1);
+
+ bitnum = find_last_bit(cpu->sve_vq_map, vq - 1);
+ return bitnum == vq - 1 ? 0 : bitnum + 1;
+}
+
static void cpu_max_get_sve_max_vq(Object *obj, Visitor *v, const char *name,
void *opaque, Error **errp)
{
@@ -287,6 +432,44 @@ static void cpu_max_set_sve_max_vq(Object *obj, Visitor *v, const char *name,
error_propagate(errp, err);
}
+static void cpu_arm_get_sve_vq(Object *obj, Visitor *v, const char *name,
+ void *opaque, Error **errp)
+{
+ ARMCPU *cpu = ARM_CPU(obj);
+ uint32_t vq = atoi(&name[3]) / 128;
+ bool value;
+
+ /* All vector lengths are disabled when SVE is off. */
+ if (!cpu_isar_feature(aa64_sve, cpu)) {
+ value = false;
+ } else {
+ value = test_bit(vq - 1, cpu->sve_vq_map);
+ }
+ visit_type_bool(v, name, &value, errp);
+}
+
+static void cpu_arm_set_sve_vq(Object *obj, Visitor *v, const char *name,
+ void *opaque, Error **errp)
+{
+ ARMCPU *cpu = ARM_CPU(obj);
+ uint32_t vq = atoi(&name[3]) / 128;
+ Error *err = NULL;
+ bool value;
+
+ visit_type_bool(v, name, &value, &err);
+ if (err) {
+ error_propagate(errp, err);
+ return;
+ }
+
+ if (value) {
+ set_bit(vq - 1, cpu->sve_vq_map);
+ } else {
+ clear_bit(vq - 1, cpu->sve_vq_map);
+ }
+ set_bit(vq - 1, cpu->sve_vq_init);
+}
+
static void cpu_arm_get_sve(Object *obj, Visitor *v, const char *name,
void *opaque, Error **errp)
{
@@ -323,6 +506,7 @@ static void cpu_arm_set_sve(Object *obj, Visitor *v, const char *name,
static void aarch64_max_initfn(Object *obj)
{
ARMCPU *cpu = ARM_CPU(obj);
+ uint32_t vq;
if (kvm_enabled()) {
kvm_arm_set_cpu_features_from_host(cpu);
@@ -426,11 +610,17 @@ static void aarch64_max_initfn(Object *obj)
cpu->dcz_blocksize = 7; /* 512 bytes */
#endif
- cpu->sve_max_vq = ARM_MAX_VQ;
object_property_add(obj, "sve-max-vq", "uint32", cpu_max_get_sve_max_vq,
cpu_max_set_sve_max_vq, NULL, NULL, &error_fatal);
object_property_add(obj, "sve", "bool", cpu_arm_get_sve,
cpu_arm_set_sve, NULL, NULL, &error_fatal);
+
+ for (vq = 1; vq <= ARM_MAX_VQ; ++vq) {
+ char name[8];
+ sprintf(name, "sve%d", vq * 128);
+ object_property_add(obj, name, "bool", cpu_arm_get_sve_vq,
+ cpu_arm_set_sve_vq, NULL, NULL, &error_fatal);
+ }
}
}
@@ -5361,6 +5361,13 @@ int sve_exception_el(CPUARMState *env, int el)
return 0;
}
+static uint32_t sve_zcr_get_valid_len(ARMCPU *cpu, uint32_t start_len)
+{
+ uint32_t start_vq = (start_len & 0xf) + 1;
+
+ return arm_cpu_vq_map_next_smaller(cpu, start_vq + 1) - 1;
+}
+
/*
* Given that SVE is enabled, return the vector length for EL.
*/
@@ -5378,7 +5385,8 @@ uint32_t sve_zcr_len_for_el(CPUARMState *env, int el)
if (arm_feature(env, ARM_FEATURE_EL3)) {
zcr_len = MIN(zcr_len, 0xf & (uint32_t)env->vfp.zcr_el[3]);
}
- return zcr_len;
+
+ return sve_zcr_get_valid_len(cpu, zcr_len);
}
static void zcr_write(CPUARMState *env, const ARMCPRegInfo *ri,
@@ -90,6 +90,8 @@ GICCapabilityList *qmp_query_gic_capabilities(Error **errp)
return head;
}
+QEMU_BUILD_BUG_ON(ARM_MAX_VQ > 16);
+
/*
* These are cpu model features we want to advertise. The order here
* matters as this is the order in which qmp_query_cpu_model_expansion
@@ -98,6 +100,9 @@ GICCapabilityList *qmp_query_gic_capabilities(Error **errp)
*/
static const char *cpu_model_advertised_features[] = {
"aarch64", "pmu", "sve",
+ "sve128", "sve256", "sve384", "sve512",
+ "sve640", "sve768", "sve896", "sve1024", "sve1152", "sve1280",
+ "sve1408", "sve1536", "sve1664", "sve1792", "sve1920", "sve2048",
NULL
};
@@ -186,6 +191,9 @@ CpuModelExpansionInfo *qmp_query_cpu_model_expansion(CpuModelExpansionType type,
if (!err) {
visit_check_struct(visitor, &err);
}
+ if (!err) {
+ arm_cpu_finalize_features(ARM_CPU(obj), &err);
+ }
visit_end_struct(visitor, NULL);
visit_free(visitor);
if (err) {
@@ -193,6 +201,10 @@ CpuModelExpansionInfo *qmp_query_cpu_model_expansion(CpuModelExpansionType type,
error_propagate(errp, err);
return NULL;
}
+ } else {
+ Error *err = NULL;
+ arm_cpu_finalize_features(ARM_CPU(obj), &err);
+ assert(err == NULL);
}
expansion_info = g_new0(CpuModelExpansionInfo, 1);
@@ -9,10 +9,17 @@
* See the COPYING file in the top-level directory.
*/
#include "qemu/osdep.h"
+#include "qemu/bitops.h"
#include "libqtest.h"
#include "qapi/qmp/qdict.h"
#include "qapi/qmp/qjson.h"
+/*
+ * We expect the SVE max-vq to be 16. Also it must be <= 64
+ * for our test code, otherwise 'vls' can't just be a uint64_t.
+ */
+#define SVE_MAX_VQ 16
+
#define MACHINE "-machine virt,gic-version=max,accel=tcg "
#define MACHINE_KVM "-machine virt,gic-version=max,accel=kvm:tcg "
#define QUERY_HEAD "{ 'execute': 'query-cpu-model-expansion', " \
@@ -175,6 +182,183 @@ static void assert_bad_props(QTestState *qts, const char *cpu_type)
qobject_unref(resp);
}
+static uint64_t resp_get_sve_vls(QDict *resp)
+{
+ QDict *props;
+ const QDictEntry *e;
+ uint64_t vls = 0;
+ int n = 0;
+
+ g_assert(resp);
+ g_assert(resp_has_props(resp));
+
+ props = resp_get_props(resp);
+
+ for (e = qdict_first(props); e; e = qdict_next(props, e)) {
+ if (strlen(e->key) > 3 && !strncmp(e->key, "sve", 3) &&
+ g_ascii_isdigit(e->key[3])) {
+ char *endptr;
+ int bits;
+
+ bits = g_ascii_strtoll(&e->key[3], &endptr, 10);
+ if (!bits || *endptr != '\0') {
+ continue;
+ }
+
+ if (qdict_get_bool(props, e->key)) {
+ vls |= BIT_ULL((bits / 128) - 1);
+ }
+ ++n;
+ }
+ }
+
+ g_assert(n == SVE_MAX_VQ);
+
+ return vls;
+}
+
+#define assert_sve_vls(qts, cpu_type, expected_vls, fmt, ...) \
+({ \
+ QDict *_resp = do_query(qts, cpu_type, fmt, ##__VA_ARGS__); \
+ g_assert(_resp); \
+ g_assert(resp_has_props(_resp)); \
+ g_assert(resp_get_sve_vls(_resp) == expected_vls); \
+ qobject_unref(_resp); \
+})
+
+static void sve_tests_default(QTestState *qts, const char *cpu_type)
+{
+ /*
+ * With no sve-max-vq or sve<N> properties on the command line
+ * the default is to have all vector lengths enabled. This also
+ * tests that 'sve' is 'on' by default.
+ */
+ assert_sve_vls(qts, cpu_type, BIT_ULL(SVE_MAX_VQ) - 1, NULL);
+
+ /* With SVE off, all vector lengths should also be off. */
+ assert_sve_vls(qts, cpu_type, 0, "{ 'sve': false }");
+
+ /* With SVE on, we must have at least one vector length enabled. */
+ assert_error(qts, cpu_type, "cannot disable sve128", "{ 'sve128': false }");
+
+ /* Basic enable/disable tests. */
+ assert_sve_vls(qts, cpu_type, 0x7, "{ 'sve384': true }");
+ assert_sve_vls(qts, cpu_type, ((BIT_ULL(SVE_MAX_VQ) - 1) & ~BIT_ULL(2)),
+ "{ 'sve384': false }");
+
+ /*
+ * ---------------------------------------------------------------------
+ * power-of-two(vq) all-power- can can
+ * of-two(< vq) enable disable
+ * ---------------------------------------------------------------------
+ * vq < max_vq no MUST* yes yes
+ * vq < max_vq yes MUST* yes no
+ * ---------------------------------------------------------------------
+ * vq == max_vq n/a MUST* yes** yes**
+ * ---------------------------------------------------------------------
+ * vq > max_vq n/a no no yes
+ * vq > max_vq n/a yes yes yes
+ * ---------------------------------------------------------------------
+ *
+ * [*] "MUST" means this requirement must already be satisfied,
+ * otherwise 'max_vq' couldn't itself be enabled.
+ *
+ * [**] Not testable with the QMP interface, only with the command line.
+ */
+
+ /* max_vq := 8 */
+ assert_sve_vls(qts, cpu_type, 0x8b, "{ 'sve1024': true }");
+
+ /* max_vq := 8, vq < max_vq, !power-of-two(vq) */
+ assert_sve_vls(qts, cpu_type, 0x8f,
+ "{ 'sve1024': true, 'sve384': true }");
+ assert_sve_vls(qts, cpu_type, 0x8b,
+ "{ 'sve1024': true, 'sve384': false }");
+
+ /* max_vq := 8, vq < max_vq, power-of-two(vq) */
+ assert_sve_vls(qts, cpu_type, 0x8b,
+ "{ 'sve1024': true, 'sve256': true }");
+ assert_error(qts, cpu_type, "cannot disable sve256",
+ "{ 'sve1024': true, 'sve256': false }");
+
+ /* max_vq := 3, vq > max_vq, !all-power-of-two(< vq) */
+ assert_error(qts, cpu_type, "cannot disable sve512",
+ "{ 'sve384': true, 'sve512': false, 'sve640': true }");
+
+ /*
+ * We can disable power-of-two vector lengths when all larger lengths
+ * are also disabled. We only need to disable the power-of-two length,
+ * as all non-enabled larger lengths will then be auto-disabled.
+ */
+ assert_sve_vls(qts, cpu_type, 0x7, "{ 'sve512': false }");
+
+ /* max_vq := 3, vq > max_vq, all-power-of-two(< vq) */
+ assert_sve_vls(qts, cpu_type, 0x1f,
+ "{ 'sve384': true, 'sve512': true, 'sve640': true }");
+ assert_sve_vls(qts, cpu_type, 0xf,
+ "{ 'sve384': true, 'sve512': true, 'sve640': false }");
+}
+
+static void sve_tests_sve_max_vq_8(const void *data)
+{
+ QTestState *qts;
+
+ qts = qtest_init(MACHINE "-cpu max,sve-max-vq=8");
+
+ assert_sve_vls(qts, "max", BIT_ULL(8) - 1, NULL);
+
+ /*
+ * Disabling the max-vq set by sve-max-vq is not allowed, but
+ * of course enabling it is OK.
+ */
+ assert_error(qts, "max", "cannot disable sve1024", "{ 'sve1024': false }");
+ assert_sve_vls(qts, "max", 0xff, "{ 'sve1024': true }");
+
+ /*
+ * Enabling anything larger than max-vq set by sve-max-vq is not
+ * allowed, but of course disabling everything larger is OK.
+ */
+ assert_error(qts, "max", "cannot enable sve1152", "{ 'sve1152': true }");
+ assert_sve_vls(qts, "max", 0xff, "{ 'sve1152': false }");
+
+ /*
+ * We can enable/disable non power-of-two lengths smaller than the
+ * max-vq set by sve-max-vq, but, while we can enable power-of-two
+ * lengths, we can't disable them.
+ */
+ assert_sve_vls(qts, "max", 0xff, "{ 'sve384': true }");
+ assert_sve_vls(qts, "max", 0xfb, "{ 'sve384': false }");
+ assert_sve_vls(qts, "max", 0xff, "{ 'sve256': true }");
+ assert_error(qts, "max", "cannot disable sve256", "{ 'sve256': false }");
+
+ qtest_quit(qts);
+}
+
+static void sve_tests_sve_off(const void *data)
+{
+ QTestState *qts;
+
+ qts = qtest_init(MACHINE "-cpu max,sve=off");
+
+ /* SVE is off, so the map should be empty. */
+ assert_sve_vls(qts, "max", 0, NULL);
+
+ /* The map stays empty even if we turn lengths off. */
+ assert_sve_vls(qts, "max", 0, "{ 'sve128': false }");
+
+ /* It's an error to enable lengths when SVE is off. */
+ assert_error(qts, "max", "cannot enable sve128", "{ 'sve128': true }");
+
+ /* With SVE re-enabled we should get all vector lengths enabled. */
+ assert_sve_vls(qts, "max", BIT_ULL(SVE_MAX_VQ) - 1, "{ 'sve': true }");
+
+ /* Or enable SVE with just specific vector lengths. */
+ assert_sve_vls(qts, "max", 0x3,
+ "{ 'sve': true, 'sve128': true, 'sve256': true }");
+
+ qtest_quit(qts);
+}
+
static void test_query_cpu_model_expansion(const void *data)
{
QTestState *qts;
@@ -198,9 +382,12 @@ static void test_query_cpu_model_expansion(const void *data)
if (g_str_equal(qtest_get_arch(), "aarch64")) {
assert_has_feature(qts, "max", "aarch64");
assert_has_feature(qts, "max", "sve");
+ assert_has_feature(qts, "max", "sve128");
assert_has_feature(qts, "cortex-a57", "pmu");
assert_has_feature(qts, "cortex-a57", "aarch64");
+ sve_tests_default(qts, "max");
+
/* Test that features that depend on KVM generate errors without. */
assert_error(qts, "max",
"'aarch64' feature cannot be disabled "
@@ -250,5 +437,12 @@ int main(int argc, char **argv)
qtest_add_data_func("/arm/kvm/query-cpu-model-expansion",
NULL, test_query_cpu_model_expansion_kvm);
+ if (g_str_equal(qtest_get_arch(), "aarch64")) {
+ qtest_add_data_func("/arm/max/query-cpu-model-expansion/sve-max-vq-8",
+ NULL, sve_tests_sve_max_vq_8);
+ qtest_add_data_func("/arm/max/query-cpu-model-expansion/sve-off",
+ NULL, sve_tests_sve_off);
+ }
+
return g_test_run();
}
@@ -48,18 +48,31 @@ block in the script for usage) is used to issue the QMP commands.
(QEMU) query-cpu-model-expansion type=full model={"name":"max"}
{ "return": {
"model": { "name": "max", "props": {
- "pmu": true, "aarch64": true
+ "sve1664": true, "pmu": true, "sve1792": true, "sve1920": true,
+ "sve128": true, "aarch64": true, "sve1024": true, "sve": true,
+ "sve640": true, "sve768": true, "sve1408": true, "sve256": true,
+ "sve1152": true, "sve512": true, "sve384": true, "sve1536": true,
+ "sve896": true, "sve1280": true, "sve2048": true
}}}}
-We see that the `max` CPU type has the `pmu` and `aarch64` CPU features.
-We also see that the CPU features are enabled, as they are all `true`.
+We see that the `max` CPU type has the `pmu`, `aarch64`, `sve`, and many
+`sve<N>` CPU features. We also see that all the CPU features are
+enabled, as they are all `true`. (The `sve<N>` CPU features are all
+optional SVE vector lengths (see "SVE CPU Properties"). While with TCG
+all SVE vector lengths can be supported, when KVM is in use it's more
+likely that only a few lengths will be supported, if SVE is supported at
+all.)
(2) Let's try to disable the PMU::
(QEMU) query-cpu-model-expansion type=full model={"name":"max","props":{"pmu":false}}
{ "return": {
"model": { "name": "max", "props": {
- "pmu": false, "aarch64": true
+ "sve1664": true, "pmu": false, "sve1792": true, "sve1920": true,
+ "sve128": true, "aarch64": true, "sve1024": true, "sve": true,
+ "sve640": true, "sve768": true, "sve1408": true, "sve256": true,
+ "sve1152": true, "sve512": true, "sve384": true, "sve1536": true,
+ "sve896": true, "sve1280": true, "sve2048": true
}}}}
We see it worked, as `pmu` is now `false`.
@@ -75,7 +88,22 @@ We see it worked, as `pmu` is now `false`.
It looks like this feature is limited to a configuration we do not
currently have.
-(4) Let's try probing CPU features for the Cortex-A15 CPU type::
+(4) Let's disable `sve` and see what happens to all the optional SVE
+ vector lengths::
+
+ (QEMU) query-cpu-model-expansion type=full model={"name":"max","props":{"sve":false}}
+ { "return": {
+ "model": { "name": "max", "props": {
+ "sve1664": false, "pmu": true, "sve1792": false, "sve1920": false,
+ "sve128": false, "aarch64": true, "sve1024": false, "sve": false,
+ "sve640": false, "sve768": false, "sve1408": false, "sve256": false,
+ "sve1152": false, "sve512": false, "sve384": false, "sve1536": false,
+ "sve896": false, "sve1280": false, "sve2048": false
+ }}}}
+
+As expected they are now all `false`.
+
+(5) Let's try probing CPU features for the Cortex-A15 CPU type::
(QEMU) query-cpu-model-expansion type=full model={"name":"cortex-a15"}
{"return": {"model": {"name": "cortex-a15", "props": {"pmu": true}}}}
@@ -131,7 +159,133 @@ After determining which CPU features are available and supported for a
given CPU type, then they may be selectively enabled or disabled on the
QEMU command line with that CPU type::
- $ qemu-system-aarch64 -M virt -cpu max,pmu=off
+ $ qemu-system-aarch64 -M virt -cpu max,pmu=off,sve=on,sve128=on,sve256=on
-The example above disables the PMU for the `max` CPU type.
+The example above disables the PMU and enables the first two SVE vector
+lengths for the `max` CPU type. Note, the `sve=on` isn't actually
+necessary, because, as we observed above with our probe of the `max` CPU
+type, `sve` is already on by default. Also, based on our probe of
+defaults, it would seem we need to disable many SVE vector lengths, rather
+than only enabling the two we want. This isn't the case, because, as
+disabling many SVE vector lengths would be quite verbose, the `sve<N>` CPU
+properties have special semantics (see "SVE CPU Property Parsing
+Semantics").
+
+SVE CPU Properties
+==================
+
+There are two types of SVE CPU properties: `sve` and `sve<N>`. The first
+is used to enable or disable the entire SVE feature, just as the `pmu`
+CPU property completely enables or disables the PMU. The second type
+is used to enable or disable specific vector lengths, where `N` is the
+number of bits of the length. The `sve<N>` CPU properties have special
+dependencies and constraints, see "SVE CPU Property Dependencies and
+Constraints" below. Additionally, as we want all supported vector lengths
+to be enabled by default, then, in order to avoid overly verbose command
+lines (command lines full of `sve<N>=off`, for all `N` not wanted), we
+provide the parsing semantics listed in "SVE CPU Property Parsing
+Semantics".
+
+SVE CPU Property Dependencies and Constraints
+---------------------------------------------
+
+ 1) At least one vector length must be enabled when `sve` is enabled.
+
+ 2) If a vector length `N` is enabled, then all power-of-two vector
+ lengths smaller than `N` must also be enabled. E.g. if `sve512`
+ is enabled, then the 128-bit and 256-bit vector lengths must also
+ be enabled.
+
+SVE CPU Property Parsing Semantics
+----------------------------------
+
+ 1) If SVE is disabled (`sve=off`), then which SVE vector lengths
+ are enabled or disabled is irrelevant to the guest, as the entire
+ SVE feature is disabled and that disables all vector lengths for
+ the guest. However QEMU will still track any `sve<N>` CPU
+ properties provided by the user. If later an `sve=on` is provided,
+ then the guest will get only the enabled lengths. If no `sve=on`
+ is provided and there are explicitly enabled vector lengths, then
+ an error is generated.
+
+ 2) If SVE is enabled (`sve=on`), but no `sve<N>` CPU properties are
+ provided, then all supported vector lengths are enabled, including
+ the non-power-of-two lengths.
+
+ 3) If SVE is enabled, then an error is generated when attempting to
+ disable the last enabled vector length (see constraint (1) of "SVE
+ CPU Property Dependencies and Constraints").
+
+ 4) If one or more vector lengths have been explicitly enabled and at
+ at least one of the dependency lengths of the maximum enabled length
+ has been explicitly disabled, then an error is generated (see
+ constraint (2) of "SVE CPU Property Dependencies and Constraints").
+
+ 5) If one or more `sve<N>` CPU properties are set `off`, but no `sve<N>`,
+ CPU properties are set `on`, then the specified vector lengths are
+ disabled but the default for any unspecified lengths remains enabled.
+ Disabling a power-of-two vector length also disables all vector
+ lengths larger than the power-of-two length (see constraint (2) of
+ "SVE CPU Property Dependencies and Constraints").
+
+ 6) If one or more `sve<N>` CPU properties are set to `on`, then they
+ are enabled and all unspecified lengths default to disabled, except
+ for the required lengths per constraint (2) of "SVE CPU Property
+ Dependencies and Constraints", which will even be auto-enabled if
+ they were not explicitly enabled.
+
+ 7) If SVE was disabled (`sve=off`), allowing all vector lengths to be
+ explicitly disabled (i.e. avoiding the error specified in (3) of
+ "SVE CPU Property Parsing Semantics"), then if later an `sve=on` is
+ provided an error will be generated. To avoid this error, one must
+ enable at least one vector length prior to enabling SVE.
+
+SVE CPU Property Examples
+-------------------------
+
+ 1) Disable SVE::
+
+ $ qemu-system-aarch64 -M virt -cpu max,sve=off
+
+ 2) Implicitly enable all vector lengths for the `max` CPU type::
+
+ $ qemu-system-aarch64 -M virt -cpu max
+
+ 3) Only enable the 128-bit vector length::
+
+ $ qemu-system-aarch64 -M virt -cpu max,sve128=on
+
+ 4) Disable the 512-bit vector length and all larger vector lengths,
+ since 512 is a power-of-two. This results in all the smaller,
+ uninitialized lengths (128, 256, and 384) defaulting to enabled::
+
+ $ qemu-system-aarch64 -M virt -cpu max,sve512=off
+
+ 5) Enable the 128-bit, 256-bit, and 512-bit vector lengths::
+
+ $ qemu-system-aarch64 -M virt -cpu max,sve128=on,sve256=on,sve512=on
+
+ 6) The same as (5), but since the 128-bit and 256-bit vector
+ lengths are required for the 512-bit vector length to be enabled,
+ then allow them to be auto-enabled::
+
+ $ qemu-system-aarch64 -M virt -cpu max,sve512=on
+
+ 7) Do the same as (6), but by first disabling SVE and then re-enabling it::
+
+ $ qemu-system-aarch64 -M virt -cpu max,sve=off,sve512=on,sve=on
+
+ 8) Force errors regarding the last vector length::
+
+ $ qemu-system-aarch64 -M virt -cpu max,sve128=off
+ $ qemu-system-aarch64 -M virt -cpu max,sve=off,sve128=off,sve=on
+
+SVE CPU Property Recommendations
+--------------------------------
+
+The examples in "SVE CPU Property Examples" exhibit many ways to select
+vector lengths which developers may find useful in order to avoid overly
+verbose command lines. However, the recommended way to select vector
+lengths is to explicitly enable each desired length. Therefore only
+example's (1), (3), and (5) exhibit recommended uses of the properties.