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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [PATCH v6 08/11] xen/lib: Add topology generator for x86
Add a helper to populate topology leaves in the cpu policy from
threads/core and cores/package counts. It's unit-tested in
test-cpu-policy.c,
but it's not connected to the rest of the code yet.
Adds the ASSERT() macro to xen/lib/x86/private.h, as it was missing.
Signed-off-by: Alejandro Vallejo <alejandro.vallejo@xxxxxxxxx>
---
tools/tests/cpu-policy/test-cpu-policy.c | 133 +++++++++++++++++++++++
xen/include/xen/lib/x86/cpu-policy.h | 16 +++
xen/lib/x86/policy.c | 88 +++++++++++++++
xen/lib/x86/private.h | 4 +
4 files changed, 241 insertions(+)
diff --git a/tools/tests/cpu-policy/test-cpu-policy.c
b/tools/tests/cpu-policy/test-cpu-policy.c
index 9216010b1c5d..870f7ecee0e5 100644
--- a/tools/tests/cpu-policy/test-cpu-policy.c
+++ b/tools/tests/cpu-policy/test-cpu-policy.c
@@ -654,6 +654,137 @@ static void test_is_compatible_failure(void)
}
}
+static void test_topo_from_parts(void)
+{
+ static const struct test {
+ unsigned int threads_per_core;
+ unsigned int cores_per_pkg;
+ struct cpu_policy policy;
+ } tests[] = {
+ {
+ .threads_per_core = 3, .cores_per_pkg = 1,
+ .policy = {
+ .x86_vendor = X86_VENDOR_AMD,
+ .topo.subleaf = {
+ { .nr_logical = 3, .level = 0, .type = 1, .id_shift = 2, },
+ { .nr_logical = 1, .level = 1, .type = 2, .id_shift = 2, },
+ },
+ },
+ },
+ {
+ .threads_per_core = 1, .cores_per_pkg = 3,
+ .policy = {
+ .x86_vendor = X86_VENDOR_AMD,
+ .topo.subleaf = {
+ { .nr_logical = 1, .level = 0, .type = 1, .id_shift = 0, },
+ { .nr_logical = 3, .level = 1, .type = 2, .id_shift = 2, },
+ },
+ },
+ },
+ {
+ .threads_per_core = 7, .cores_per_pkg = 5,
+ .policy = {
+ .x86_vendor = X86_VENDOR_AMD,
+ .topo.subleaf = {
+ { .nr_logical = 7, .level = 0, .type = 1, .id_shift = 3, },
+ { .nr_logical = 5, .level = 1, .type = 2, .id_shift = 6, },
+ },
+ },
+ },
+ {
+ .threads_per_core = 2, .cores_per_pkg = 128,
+ .policy = {
+ .x86_vendor = X86_VENDOR_AMD,
+ .topo.subleaf = {
+ { .nr_logical = 2, .level = 0, .type = 1, .id_shift = 1, },
+ { .nr_logical = 128, .level = 1, .type = 2,
+ .id_shift = 8, },
+ },
+ },
+ },
+ {
+ .threads_per_core = 3, .cores_per_pkg = 1,
+ .policy = {
+ .x86_vendor = X86_VENDOR_INTEL,
+ .topo.subleaf = {
+ { .nr_logical = 3, .level = 0, .type = 1, .id_shift = 2, },
+ { .nr_logical = 3, .level = 1, .type = 2, .id_shift = 2, },
+ },
+ },
+ },
+ {
+ .threads_per_core = 1, .cores_per_pkg = 3,
+ .policy = {
+ .x86_vendor = X86_VENDOR_INTEL,
+ .topo.subleaf = {
+ { .nr_logical = 1, .level = 0, .type = 1, .id_shift = 0, },
+ { .nr_logical = 3, .level = 1, .type = 2, .id_shift = 2, },
+ },
+ },
+ },
+ {
+ .threads_per_core = 7, .cores_per_pkg = 5,
+ .policy = {
+ .x86_vendor = X86_VENDOR_INTEL,
+ .topo.subleaf = {
+ { .nr_logical = 7, .level = 0, .type = 1, .id_shift = 3, },
+ { .nr_logical = 35, .level = 1, .type = 2, .id_shift = 6,
},
+ },
+ },
+ },
+ {
+ .threads_per_core = 2, .cores_per_pkg = 128,
+ .policy = {
+ .x86_vendor = X86_VENDOR_INTEL,
+ .topo.subleaf = {
+ { .nr_logical = 2, .level = 0, .type = 1, .id_shift = 1, },
+ { .nr_logical = 256, .level = 1, .type = 2,
+ .id_shift = 8, },
+ },
+ },
+ },
+ };
+
+ printf("Testing topology synthesis from parts:\n");
+
+ for ( size_t i = 0; i < ARRAY_SIZE(tests); ++i )
+ {
+ const struct test *t = &tests[i];
+ struct cpu_policy actual = { .x86_vendor = t->policy.x86_vendor };
+ int rc = x86_topo_from_parts(&actual, t->threads_per_core,
+ t->cores_per_pkg);
+
+ if ( rc || memcmp(&actual.topo, &t->policy.topo, sizeof(actual.topo)) )
+ {
+#define TOPO(n, f) t->policy.topo.subleaf[(n)].f, actual.topo.subleaf[(n)].f
+ fail("FAIL[%d] - '%s %u t/c, %u c/p'\n",
+ rc,
+ x86_cpuid_vendor_to_str(t->policy.x86_vendor),
+ t->threads_per_core, t->cores_per_pkg);
+ printf(" subleaf=%u expected_n=%u actual_n=%u\n"
+ " expected_lvl=%u actual_lvl=%u\n"
+ " expected_type=%u actual_type=%u\n"
+ " expected_shift=%u actual_shift=%u\n",
+ 0,
+ TOPO(0, nr_logical),
+ TOPO(0, level),
+ TOPO(0, type),
+ TOPO(0, id_shift));
+
+ printf(" subleaf=%u expected_n=%u actual_n=%u\n"
+ " expected_lvl=%u actual_lvl=%u\n"
+ " expected_type=%u actual_type=%u\n"
+ " expected_shift=%u actual_shift=%u\n",
+ 1,
+ TOPO(1, nr_logical),
+ TOPO(1, level),
+ TOPO(1, type),
+ TOPO(1, id_shift));
+#undef TOPO
+ }
+ }
+}
+
int main(int argc, char **argv)
{
printf("CPU Policy unit tests\n");
@@ -671,6 +802,8 @@ int main(int argc, char **argv)
test_is_compatible_success();
test_is_compatible_failure();
+ test_topo_from_parts();
+
if ( nr_failures )
printf("Done: %u failures\n", nr_failures);
else
diff --git a/xen/include/xen/lib/x86/cpu-policy.h
b/xen/include/xen/lib/x86/cpu-policy.h
index f43e1a3b21e9..116b305a1d7f 100644
--- a/xen/include/xen/lib/x86/cpu-policy.h
+++ b/xen/include/xen/lib/x86/cpu-policy.h
@@ -542,6 +542,22 @@ int x86_cpu_policies_are_compatible(const struct
cpu_policy *host,
const struct cpu_policy *guest,
struct cpu_policy_errors *err);
+/**
+ * Synthesise topology information in `p` given high-level constraints
+ *
+ * Topology is given in various fields accross several leaves, some of
+ * which are vendor-specific. This function uses the policy itself to
+ * derive such leaves from threads/core and cores/package.
+ *
+ * @param p CPU policy of the domain.
+ * @param threads_per_core threads/core. Doesn't need to be a power of 2.
+ * @param cores_per_package cores/package. Doesn't need to be a power of 2.
+ * @return 0 on success; -errno on failure
+ */
+int x86_topo_from_parts(struct cpu_policy *p,
+ unsigned int threads_per_core,
+ unsigned int cores_per_pkg);
+
#endif /* !XEN_LIB_X86_POLICIES_H */
/*
diff --git a/xen/lib/x86/policy.c b/xen/lib/x86/policy.c
index 63bc96451d2c..16b09a427841 100644
--- a/xen/lib/x86/policy.c
+++ b/xen/lib/x86/policy.c
@@ -2,6 +2,94 @@
#include <xen/lib/x86/cpu-policy.h>
+static unsigned int order(unsigned int n)
+{
+ ASSERT(n); /* clz(0) is UB */
+
+ return 8 * sizeof(n) - __builtin_clz(n);
+}
+
+int x86_topo_from_parts(struct cpu_policy *p,
+ unsigned int threads_per_core,
+ unsigned int cores_per_pkg)
+{
+ unsigned int threads_per_pkg = threads_per_core * cores_per_pkg;
+ unsigned int apic_id_size;
+
+ if ( !p || !threads_per_core || !cores_per_pkg )
+ return -EINVAL;
+
+ p->basic.max_leaf = MAX(0xb, p->basic.max_leaf);
+
+ memset(p->topo.raw, 0, sizeof(p->topo.raw));
+
+ /* thread level */
+ p->topo.subleaf[0].nr_logical = threads_per_core;
+ p->topo.subleaf[0].id_shift = 0;
+ p->topo.subleaf[0].level = 0;
+ p->topo.subleaf[0].type = 1;
+ if ( threads_per_core > 1 )
+ p->topo.subleaf[0].id_shift = order(threads_per_core - 1);
+
+ /* core level */
+ p->topo.subleaf[1].nr_logical = cores_per_pkg;
+ if ( p->x86_vendor == X86_VENDOR_INTEL )
+ p->topo.subleaf[1].nr_logical = threads_per_pkg;
+ p->topo.subleaf[1].id_shift = p->topo.subleaf[0].id_shift;
+ p->topo.subleaf[1].level = 1;
+ p->topo.subleaf[1].type = 2;
+ if ( cores_per_pkg > 1 )
+ p->topo.subleaf[1].id_shift += order(cores_per_pkg - 1);
+
+ apic_id_size = p->topo.subleaf[1].id_shift;
+
+ /*
+ * Contrary to what the name might seem to imply. HTT is an enabler for
+ * SMP and there's no harm in setting it even with a single vCPU.
+ */
+ p->basic.htt = true;
+ p->basic.lppp = MIN(0xff, threads_per_pkg);
+
+ switch ( p->x86_vendor )
+ {
+ case X86_VENDOR_INTEL: {
+ struct cpuid_cache_leaf *sl = p->cache.subleaf;
+
+ for ( size_t i = 0; sl->type &&
+ i < ARRAY_SIZE(p->cache.raw); i++, sl++ )
+ {
+ sl->cores_per_package = cores_per_pkg - 1;
+ sl->threads_per_cache = threads_per_core - 1;
+ if ( sl->type == 3 /* unified cache */ )
+ sl->threads_per_cache = threads_per_pkg - 1;
+ }
+ break;
+ }
+
+ case X86_VENDOR_AMD:
+ case X86_VENDOR_HYGON:
+ /* Expose p->basic.lppp */
+ p->extd.cmp_legacy = true;
+
+ /* Clip NC to the maximum value it can hold */
+ p->extd.nc = MIN(0xff, threads_per_pkg - 1);
+
+ /* TODO: Expose leaf e1E */
+ p->extd.topoext = false;
+
+ /*
+ * Clip APIC ID to 8 bits, as that's what high core-count machines do.
+ *
+ * That's what AMD EPYC 9654 does with >256 CPUs.
+ */
+ p->extd.apic_id_size = MIN(8, apic_id_size);
+
+ break;
+ }
+
+ return 0;
+}
+
int x86_cpu_policies_are_compatible(const struct cpu_policy *host,
const struct cpu_policy *guest,
struct cpu_policy_errors *err)
diff --git a/xen/lib/x86/private.h b/xen/lib/x86/private.h
index 60bb82a400b7..2ec9dbee33c2 100644
--- a/xen/lib/x86/private.h
+++ b/xen/lib/x86/private.h
@@ -4,6 +4,7 @@
#ifdef __XEN__
#include <xen/bitops.h>
+#include <xen/bug.h>
#include <xen/guest_access.h>
#include <xen/kernel.h>
#include <xen/lib.h>
@@ -17,6 +18,7 @@
#else
+#include <assert.h>
#include <errno.h>
#include <inttypes.h>
#include <stdbool.h>
@@ -28,6 +30,8 @@
#include <xen-tools/common-macros.h>
+#define ASSERT(x) assert(x)
+
static inline bool test_bit(unsigned int bit, const void *vaddr)
{
const char *addr = vaddr;
--
2.46.0
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