Re: [Qemu-devel] [RFC 14/15] i386: topology & APIC ID utility functions (v2)

[Igor Mammedov <imammedo@redhat.com>]

On Tue,  7 Aug 2012 16:56:52 -0300
Eduardo Habkost <ehabkost@redhat.com> wrote:

> Changes v1 -> v2:
>  - Support 32-bit APIC IDs (in case x2APIC is going to be used)
>  - Coding style changes
>  - Use TARGET_I386_TOPOLOGY_H instead of __QEMU_X86_TOPOLOGY_H__
>  - Rename topo_make_apic_id() to topo_apicid_for_cpu()
>  - Rename __make_apicid() to topo_make_apicid()
>  - Spaces around operators on test-x86-cpuid.c, as requested by
>    Blue Swirl
>  - Make test-x86-cpuid a target-specific test

adding to commit description ref to intel(& maybe amd) spec or/and short
description how apicid is structured/constructed would be nice

> Cc: Blue Swirl <blauwirbel@gmail.com>
> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> ---
>  target-i386/topology.h | 144 +++++++++++++++++++++++++++++++++++++++++++++++++
>  tests/.gitignore       |   1 +
>  tests/Makefile         |   3 ++
>  tests/test-x86-cpuid.c | 108 +++++++++++++++++++++++++++++++++++++
>  4 files changed, 256 insertions(+)
>  create mode 100644 target-i386/topology.h
>  create mode 100644 tests/test-x86-cpuid.c
> 
> diff --git a/target-i386/topology.h b/target-i386/topology.h
> new file mode 100644
> index 0000000..35d9817
> --- /dev/null
> +++ b/target-i386/topology.h
> @@ -0,0 +1,144 @@
> +/*
> + *  x86 CPU topology data structures and functions
> + *
> + *  Copyright (c) 2012 Red Hat Inc.
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a copy
> + * of this software and associated documentation files (the "Software"), to deal
> + * in the Software without restriction, including without limitation the rights
> + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
> + * copies of the Software, and to permit persons to whom the Software is
> + * furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice shall be included in
> + * all copies or substantial portions of the Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
> + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
> + * THE SOFTWARE.
> + */
> +#ifndef TARGET_I386_TOPOLOGY_H
> +#define TARGET_I386_TOPOLOGY_H
> +
> +#include <stdint.h>
> +#include <string.h>
> +
> +#include "bitops.h"
> +
> +/* APIC IDs can be 32-bit, but beware: APIC IDs > 255 require x2APIC support
> + */
> +typedef uint32_t apic_id_t;
> +
> +/* Return the bit width needed for 'count' IDs
> + */
> +static unsigned bits_for_count(unsigned count)
bitwidth_for_count(...) perhaps would be clearer?
and you could drop apicid_*_width/apicid_*_offset () funcs and use
it directly in topo_make_apicid() to make code more concise

> +{
> +    g_assert(count >= 1);
> +    if (count == 1) {
> +        return 0;
> +    }
> +    return bitops_flsl(count - 1) + 1;
> +}
> +
> +/* Bit width of the SMT_ID (thread ID) field on the APIC ID
> + */
> +static inline unsigned apicid_smt_width(unsigned nr_cores, unsigned nr_threads)
> +{
> +    return bits_for_count(nr_threads);
> +}
> +
> +/* Bit width of the Core_ID field
> + */
> +static inline unsigned apicid_core_width(unsigned nr_cores, unsigned nr_threads)
> +{
> +    return bits_for_count(nr_cores);
> +}
> +
> +/* Bit offset of the Core_ID field
> + */
> +static inline unsigned apicid_core_offset(unsigned nr_cores,
> +                                          unsigned nr_threads)
> +{
> +    return apicid_smt_width(nr_cores, nr_threads);
> +}
> +
> +/* Bit offset of the Pkg_ID (socket ID) field
> + */
> +static inline unsigned apicid_pkg_offset(unsigned nr_cores, unsigned nr_threads)
> +{
> +    return apicid_core_offset(nr_cores, nr_threads) + \
> +           apicid_core_width(nr_cores, nr_threads);
> +}
> +
> +/* Make APIC ID for the CPU based on Pkg_ID, Core_ID, SMT_ID
> + *
> + * The caller must make sure core_id < nr_cores and smt_id < nr_threads.
> + */
> +static inline apic_id_t topo_make_apicid(unsigned nr_cores,
> +                                         unsigned nr_threads,
> +                                         unsigned pkg_id, unsigned core_id,
> +                                         unsigned smt_id)
> +{
> +    return (pkg_id  << apicid_pkg_offset(nr_cores, nr_threads)) | \
> +           (core_id << apicid_core_offset(nr_cores, nr_threads)) | \
> +           smt_id;
> +}
Looks like it considers only Intel spec, would it be correct for AMD case?
see support.amd.com/us/Embedded_TechDocs/25481.pdf "3.2 Extended Method"

AMD doesn't have SMT, perhaps nr_threads should be enforced to 1 when VCPU is
AMD?

> +
> +/* Calculate thread/core/package IDs for a specific topology,
> + * based on (continguous) CPU index
> + */
> +static inline void topo_ids_from_idx(unsigned nr_cores, unsigned nr_threads,
> +                                     unsigned cpu_index,
> +                                     unsigned *pkg_id, unsigned *core_id,
> +                                     unsigned *smt_id)
> +{
> +    unsigned core_index = cpu_index / nr_threads;
> +    *smt_id = cpu_index % nr_threads;
> +    *core_id = core_index % nr_cores;
> +    *pkg_id = core_index / nr_cores;
> +}
> +
> +/* Get package ID from an APIC ID
> + */
> +static inline unsigned apicid_pkg_id(unsigned nr_cores, unsigned nr_threads,
> +                                     apic_id_t apic_id)
> +{
> +    return apic_id >> apicid_pkg_offset(nr_cores, nr_threads);
> +}
> +
> +/* Get core ID from an APIC ID
> + */
> +static inline unsigned apicid_core_id(unsigned nr_cores, unsigned nr_threads,
> +                                      apic_id_t apic_id)
> +{
> +    return (apic_id >> apicid_core_offset(nr_cores, nr_threads)) & \
> +           ((1 << apicid_core_width(nr_cores, nr_threads)) - 1);
> +}
> +
> +/* Get SMT (thread) ID from an APIC ID
> + */
> +static inline unsigned apicid_smt_id(unsigned nr_cores, unsigned nr_threads,
> +                                     apic_id_t apic_id)
> +{
> +    return apic_id & ((1 << apicid_smt_width(nr_cores, nr_threads)) - 1);
> +}
Are above getters necessary for fix to work or are there plans to use them?

> +
> +/* Make APIC ID for the CPU 'cpu_index'
> + *
> + * 'cpu_index' is a sequential, contiguous ID for the CPU.
> + */
> +static inline apic_id_t topo_apicid_for_cpu(unsigned nr_cores,
> +                                            unsigned nr_threads,
> +                                            unsigned cpu_index)
> +{
> +    unsigned pkg_id, core_id, smt_id;
> +    topo_ids_from_idx(nr_cores, nr_threads, cpu_index,
> +                      &pkg_id, &core_id, &smt_id);
> +    return topo_make_apicid(nr_cores, nr_threads, pkg_id, core_id, smt_id);
> +}
> +
> +#endif /* TARGET_I386_TOPOLOGY_H */
> diff --git a/tests/.gitignore b/tests/.gitignore
> index f9041f3..38c94ef 100644
> --- a/tests/.gitignore
> +++ b/tests/.gitignore
> @@ -10,4 +10,5 @@ test-qmp-commands.h
>  test-qmp-commands
>  test-qmp-input-strict
>  test-qmp-marshal.c
> +test-x86-cpuid
>  *-test
> diff --git a/tests/Makefile b/tests/Makefile
> index 79796aa..e74efdd 100644
> --- a/tests/Makefile
> +++ b/tests/Makefile
> @@ -15,6 +15,7 @@ check-unit-y += tests/test-string-output-visitor$(EXESUF)
>  check-unit-y += tests/test-coroutine$(EXESUF)
>  check-unit-y += tests/test-visitor-serialization$(EXESUF)
>  check-unit-y += tests/test-iov$(EXESUF)
> +check-unit-i386-y += tests/test-x86-cpuid$(EXESUF)
>  
>  check-block-$(CONFIG_POSIX) += tests/qemu-iotests-quick.sh
>  
> @@ -35,6 +36,7 @@ test-obj-y = tests/check-qint.o tests/check-qstring.o tests/check-qdict.o \
>  	tests/test-string-input-visitor.o tests/test-qmp-output-visitor.o \
>  	tests/test-qmp-input-visitor.o tests/test-qmp-input-strict.o \
>  	tests/test-qmp-commands.o tests/test-visitor-serialization.o
> +test-obj-i386-y = tests/test-x86-cpuid.o
>  
>  test-qapi-obj-y =  $(qobject-obj-y) $(qapi-obj-y) $(tools-obj-y)
>  test-qapi-obj-y += tests/test-qapi-visit.o tests/test-qapi-types.o
> @@ -48,6 +50,7 @@ tests/check-qfloat$(EXESUF): tests/check-qfloat.o qfloat.o $(tools-obj-y)
>  tests/check-qjson$(EXESUF): tests/check-qjson.o $(qobject-obj-y) $(tools-obj-y)
>  tests/test-coroutine$(EXESUF): tests/test-coroutine.o $(coroutine-obj-y) $(tools-obj-y)
>  tests/test-iov$(EXESUF): tests/test-iov.o iov.o
> +tests/test-x86-cpuid$(EXESUF): tests/test-x86-cpuid.o
>  
>  tests/test-qapi-types.c tests/test-qapi-types.h :\
>  $(SRC_PATH)/qapi-schema-test.json $(SRC_PATH)/scripts/qapi-types.py
> diff --git a/tests/test-x86-cpuid.c b/tests/test-x86-cpuid.c
> new file mode 100644
> index 0000000..d782c9c
> --- /dev/null
> +++ b/tests/test-x86-cpuid.c
> @@ -0,0 +1,108 @@
> +/*
> + *  Test code for x86 CPUID and Topology functions
> + *
> + *  Copyright (c) 2012 Red Hat Inc.
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a copy
> + * of this software and associated documentation files (the "Software"), to deal
> + * in the Software without restriction, including without limitation the rights
> + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
> + * copies of the Software, and to permit persons to whom the Software is
> + * furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice shall be included in
> + * all copies or substantial portions of the Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
> + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
> + * THE SOFTWARE.
> + */
> +
> +#include <glib.h>
> +
> +/*FIXME: this should be built inside the i386 target directory instead */
> +#include "topology.h"
> +
> +static void test_topo_bits(void)
> +{
> +    /* simple tests for 1 thread per core, 1 core per socket */
> +    g_assert_cmpuint(apicid_smt_width(1, 1), ==, 0);
> +    g_assert_cmpuint(apicid_core_width(1, 1), ==, 0);
> +
> +    g_assert_cmpuint(topo_apicid_for_cpu(1, 1, 0), ==, 0);
> +    g_assert_cmpuint(topo_apicid_for_cpu(1, 1, 1), ==, 1);
> +    g_assert_cmpuint(topo_apicid_for_cpu(1, 1, 2), ==, 2);
> +    g_assert_cmpuint(topo_apicid_for_cpu(1, 1, 3), ==, 3);
> +
> +
> +    /* Test field width calculation for multiple values
> +     */
> +    g_assert_cmpuint(apicid_smt_width(1, 2), ==, 1);
> +    g_assert_cmpuint(apicid_smt_width(1, 3), ==, 2);
> +    g_assert_cmpuint(apicid_smt_width(1, 4), ==, 2);
> +
> +    g_assert_cmpuint(apicid_smt_width(1, 14), ==, 4);
> +    g_assert_cmpuint(apicid_smt_width(1, 15), ==, 4);
> +    g_assert_cmpuint(apicid_smt_width(1, 16), ==, 4);
> +    g_assert_cmpuint(apicid_smt_width(1, 17), ==, 5);
> +
> +
> +    g_assert_cmpuint(apicid_core_width(30, 2), ==, 5);
> +    g_assert_cmpuint(apicid_core_width(31, 2), ==, 5);
> +    g_assert_cmpuint(apicid_core_width(32, 2), ==, 5);
> +    g_assert_cmpuint(apicid_core_width(33, 2), ==, 6);
> +
> +
> +    /* build a weird topology and see if IDs are calculated correctly
> +     */
> +
> +    /* This will use 2 bits for thread ID and 3 bits for core ID
> +     */
> +    g_assert_cmpuint( apicid_smt_width(6, 3), ==, 2);
> +    g_assert_cmpuint(apicid_core_width(6, 3), ==, 3);
> +    g_assert_cmpuint(apicid_pkg_offset(6, 3), ==, 5);
> +
> +    g_assert_cmpuint(topo_apicid_for_cpu(6, 3, 0), ==, 0);
> +    g_assert_cmpuint(topo_apicid_for_cpu(6, 3, 1), ==, 1);
> +    g_assert_cmpuint(topo_apicid_for_cpu(6, 3, 2), ==, 2);
> +
> +    g_assert_cmpuint(topo_apicid_for_cpu(6, 3, 1 * 3 + 0), ==, (1 << 2) | 0);
> +    g_assert_cmpuint(topo_apicid_for_cpu(6, 3, 1 * 3 + 1), ==, (1 << 2) | 1);
> +    g_assert_cmpuint(topo_apicid_for_cpu(6, 3, 1 * 3 + 2), ==, (1 << 2) | 2);
> +
> +    g_assert_cmpuint(topo_apicid_for_cpu(6, 3, 2 * 3 + 0), ==, (2 << 2) | 0);
> +    g_assert_cmpuint(topo_apicid_for_cpu(6, 3, 2 * 3 + 1), ==, (2 << 2) | 1);
> +    g_assert_cmpuint(topo_apicid_for_cpu(6, 3, 2 * 3 + 2), ==, (2 << 2) | 2);
> +
> +    g_assert_cmpuint(topo_apicid_for_cpu(6, 3, 5 * 3 + 0), ==, (5 << 2) | 0);
> +    g_assert_cmpuint(topo_apicid_for_cpu(6, 3, 5 * 3 + 1), ==, (5 << 2) | 1);
> +    g_assert_cmpuint(topo_apicid_for_cpu(6, 3, 5 * 3 + 2), ==, (5 << 2) | 2);
> +
> +    g_assert_cmpuint(topo_apicid_for_cpu(6, 3, 1 * 6 * 3 + 0 * 3 + 0), ==,
> +                                         (1 << 5));
> +    g_assert_cmpuint(topo_apicid_for_cpu(6, 3, 1 * 6 * 3 + 1 * 3 + 1), ==,
> +                                         (1 << 5) | (1 << 2) | 1);
> +    g_assert_cmpuint(topo_apicid_for_cpu(6, 3, 3 * 6 * 3 + 5 * 3 + 2), ==,
> +                                         (3 << 5) | (5 << 2) | 2);
> +
> +
> +    /* Check the APIC ID -> {pkg,core,thread} ID functions */
> +    g_assert_cmpuint( apicid_pkg_id(6, 3, (3 << 5) | (5 << 2) | 2), ==, 3);
> +    g_assert_cmpuint(apicid_core_id(6, 3, (3 << 5) | (5 << 2) | 2), ==, 5);
> +    g_assert_cmpuint( apicid_smt_id(6, 3, (3 << 5) | (5 << 2) | 2), ==, 2);
> +}
> +
> +int main(int argc, char **argv)
> +{
> +    g_test_init(&argc, &argv, NULL);
> +
> +    g_test_add_func("/cpuid/topology/basic", test_topo_bits);
> +
> +    g_test_run();
> +
> +    return 0;
> +}
> -- 
> 1.7.11.2
> 
> 


-- 
Regards,
  Igor