On Fri, Oct 11, 2024 at 10:14 AM Dr. David Alan Gilbert
<d...@treblig.org> wrote:
>
> * Yichen Wang (yichen.w...@bytedance.com) wrote:
> > From: Hao Xiang <hao.xi...@linux.dev>
>
> Please split the cpuid stuff out into a separate patch; it feels like
> it should be in some x86 specific place.
DSA is an Intel feature/device, and it only makes sense on x86. I
mean, dsa.c already implies that it is a x86 specific feature. So I
guess keeping it in the dsa.c is a better option?
>
> > Intel DSA offloading is an optional feature that turns on if
> > proper hardware and software stack is available. To turn on
> > DSA offloading in multifd live migration by setting:
> >
> > zero-page-detection=dsa-accel
> > dsa-accel-path=[dsa_dev_path1] [dsa_dev_path2] ... [dsa_dev_pathX]
>
> I'd like to suggest changing that to:
>
> accel-path=dsa:dev_path1 dsa:dev_path2 somethingelse:dev_path2 etc
>
> that means we don't need a new option when someone adds a different
> accelerator.
It all depends on the implementation of "other accelerators". I am OK
with this change if you believe that is better.
>
> Dave
> > This feature is turned off by default.
> >
> > Signed-off-by: Hao Xiang <hao.xi...@linux.dev>
> > Signed-off-by: Yichen Wang <yichen.w...@bytedance.com>
> > ---
> > hmp-commands.hx | 2 +-
> > include/qemu/dsa.h | 13 +++++++++++++
> > migration/migration-hmp-cmds.c | 19 ++++++++++++++++++-
> > migration/options.c | 30 ++++++++++++++++++++++++++++++
> > migration/options.h | 1 +
> > qapi/migration.json | 32 ++++++++++++++++++++++++++++----
> > util/dsa.c | 31 +++++++++++++++++++++++++++++++
> > 7 files changed, 122 insertions(+), 6 deletions(-)
> >
> > diff --git a/hmp-commands.hx b/hmp-commands.hx
> > index 06746f0afc..0e04eac7c7 100644
> > --- a/hmp-commands.hx
> > +++ b/hmp-commands.hx
> > @@ -1009,7 +1009,7 @@ ERST
> >
> > {
> > .name = "migrate_set_parameter",
> > - .args_type = "parameter:s,value:s",
> > + .args_type = "parameter:s,value:S",
>
> Can you show the case you need this for?
>
That is used for pass a strList in the QEMU CLI. Without this change,
I cannot do:
migrate_set_parameter dsa-accel-path /dev/dsa/wq0.1 /dev/dsa/wq0.1
and it will complain.
> Dave
>
> > .params = "parameter value",
> > .help = "Set the parameter for migration",
> > .cmd = hmp_migrate_set_parameter,
> > diff --git a/include/qemu/dsa.h b/include/qemu/dsa.h
> > index a3b502ee41..b1bb6daad2 100644
> > --- a/include/qemu/dsa.h
> > +++ b/include/qemu/dsa.h
> > @@ -100,6 +100,13 @@ void qemu_dsa_stop(void);
> > */
> > void qemu_dsa_cleanup(void);
> >
> > +/**
> > + * @brief Check if DSA is supported.
> > + *
> > + * @return True if DSA is supported, otherwise false.
> > + */
> > +bool qemu_dsa_is_supported(void);
> > +
> > /**
> > * @brief Check if DSA is running.
> > *
> > @@ -141,6 +148,12 @@ buffer_is_zero_dsa_batch_sync(QemuDsaBatchTask
> > *batch_task,
> >
> > typedef struct QemuDsaBatchTask {} QemuDsaBatchTask;
> >
> > +static inline bool qemu_dsa_is_supported(void)
> > +{
> > + return false;
> > +}
> > +
> > +
> > static inline bool qemu_dsa_is_running(void)
> > {
> > return false;
> > diff --git a/migration/migration-hmp-cmds.c b/migration/migration-hmp-cmds.c
> > index 20d1a6e219..983f13b73c 100644
> > --- a/migration/migration-hmp-cmds.c
> > +++ b/migration/migration-hmp-cmds.c
> > @@ -312,7 +312,16 @@ void hmp_info_migrate_parameters(Monitor *mon, const
> > QDict *qdict)
> > monitor_printf(mon, "%s: '%s'\n",
> > MigrationParameter_str(MIGRATION_PARAMETER_TLS_AUTHZ),
> > params->tls_authz);
> > -
> > + if (params->has_dsa_accel_path) {
> > + strList *dsa_accel_path = params->dsa_accel_path;
> > + monitor_printf(mon, "%s:",
> > +
> > MigrationParameter_str(MIGRATION_PARAMETER_DSA_ACCEL_PATH));
> > + while (dsa_accel_path) {
> > + monitor_printf(mon, " '%s'", dsa_accel_path->value);
> > + dsa_accel_path = dsa_accel_path->next;
> > + }
> > + monitor_printf(mon, "\n");
> > + }
> > if (params->has_block_bitmap_mapping) {
> > const BitmapMigrationNodeAliasList *bmnal;
> >
> > @@ -563,6 +572,14 @@ void hmp_migrate_set_parameter(Monitor *mon, const
> > QDict *qdict)
> > p->has_x_checkpoint_delay = true;
> > visit_type_uint32(v, param, &p->x_checkpoint_delay, &err);
> > break;
> > + case MIGRATION_PARAMETER_DSA_ACCEL_PATH:
> > + p->has_dsa_accel_path = true;
> > + g_autofree char **strv = g_strsplit(valuestr ? : "", " ", -1);
> > + strList **tail = &p->dsa_accel_path;
> > + for (int i = 0; strv[i]; i++) {
> > + QAPI_LIST_APPEND(tail, strv[i]);
> > + }
> > + break;
> > case MIGRATION_PARAMETER_MULTIFD_CHANNELS:
> > p->has_multifd_channels = true;
> > visit_type_uint8(v, param, &p->multifd_channels, &err);
> > diff --git a/migration/options.c b/migration/options.c
> > index 147cd2b8fd..a0b3a7d291 100644
> > --- a/migration/options.c
> > +++ b/migration/options.c
> > @@ -13,6 +13,7 @@
> >
> > #include "qemu/osdep.h"
> > #include "qemu/error-report.h"
> > +#include "qemu/dsa.h"
> > #include "exec/target_page.h"
> > #include "qapi/clone-visitor.h"
> > #include "qapi/error.h"
> > @@ -832,6 +833,13 @@ const char *migrate_tls_creds(void)
> > return s->parameters.tls_creds;
> > }
> >
> > +const strList *migrate_dsa_accel_path(void)
> > +{
> > + MigrationState *s = migrate_get_current();
> > +
> > + return s->parameters.dsa_accel_path;
> > +}
> > +
> > const char *migrate_tls_hostname(void)
> > {
> > MigrationState *s = migrate_get_current();
> > @@ -945,6 +953,8 @@ MigrationParameters *qmp_query_migrate_parameters(Error
> > **errp)
> > params->zero_page_detection = s->parameters.zero_page_detection;
> > params->has_direct_io = true;
> > params->direct_io = s->parameters.direct_io;
> > + params->has_dsa_accel_path = true;
> > + params->dsa_accel_path = QAPI_CLONE(strList,
> > s->parameters.dsa_accel_path);
> >
> > return params;
> > }
> > @@ -953,6 +963,7 @@ void migrate_params_init(MigrationParameters *params)
> > {
> > params->tls_hostname = g_strdup("");
> > params->tls_creds = g_strdup("");
> > + params->dsa_accel_path = NULL;
> >
> > /* Set has_* up only for parameter checks */
> > params->has_throttle_trigger_threshold = true;
> > @@ -1165,6 +1176,14 @@ bool migrate_params_check(MigrationParameters
> > *params, Error **errp)
> > return false;
> > }
> >
> > + if (params->has_zero_page_detection &&
> > + params->zero_page_detection == ZERO_PAGE_DETECTION_DSA_ACCEL) {
> > + if (!qemu_dsa_is_supported()) {
> > + error_setg(errp, "DSA acceleration is not supported.");
> > + return false;
> > + }
> > + }
> > +
> > return true;
> > }
> >
> > @@ -1278,6 +1297,11 @@ static void
> > migrate_params_test_apply(MigrateSetParameters *params,
> > if (params->has_direct_io) {
> > dest->direct_io = params->direct_io;
> > }
> > +
> > + if (params->has_dsa_accel_path) {
> > + dest->has_dsa_accel_path = true;
> > + dest->dsa_accel_path = params->dsa_accel_path;
> > + }
> > }
> >
> > static void migrate_params_apply(MigrateSetParameters *params, Error
> > **errp)
> > @@ -1410,6 +1434,12 @@ static void
> > migrate_params_apply(MigrateSetParameters *params, Error **errp)
> > if (params->has_direct_io) {
> > s->parameters.direct_io = params->direct_io;
> > }
> > + if (params->has_dsa_accel_path) {
> > + qapi_free_strList(s->parameters.dsa_accel_path);
> > + s->parameters.has_dsa_accel_path = true;
> > + s->parameters.dsa_accel_path =
> > + QAPI_CLONE(strList, params->dsa_accel_path);
> > + }
> > }
> >
> > void qmp_migrate_set_parameters(MigrateSetParameters *params, Error **errp)
> > diff --git a/migration/options.h b/migration/options.h
> > index a0bd6edc06..8198b220bd 100644
> > --- a/migration/options.h
> > +++ b/migration/options.h
> > @@ -86,6 +86,7 @@ const char *migrate_tls_creds(void);
> > const char *migrate_tls_hostname(void);
> > uint64_t migrate_xbzrle_cache_size(void);
> > ZeroPageDetection migrate_zero_page_detection(void);
> > +const strList *migrate_dsa_accel_path(void);
> >
> > /* parameters helpers */
> >
> > diff --git a/qapi/migration.json b/qapi/migration.json
> > index b66cccf107..d8b42ceae6 100644
> > --- a/qapi/migration.json
> > +++ b/qapi/migration.json
> > @@ -626,10 +626,14 @@
> > # multifd migration is enabled, else in the main migration thread
> > # as for @legacy.
> > #
> > +# @dsa-accel: Perform zero page checking with the DSA accelerator
> > +# offloading in multifd sender thread if multifd migration is
> > +# enabled, else in the main migration thread as for @legacy.
> > +#
> > # Since: 9.0
> > ##
> > { 'enum': 'ZeroPageDetection',
> > - 'data': [ 'none', 'legacy', 'multifd' ] }
> > + 'data': [ 'none', 'legacy', 'multifd', 'dsa-accel' ] }
> >
> > ##
> > # @BitmapMigrationBitmapAliasTransform:
> > @@ -837,6 +841,12 @@
> > # See description in @ZeroPageDetection. Default is 'multifd'.
> > # (since 9.0)
> > #
> > +# @dsa-accel-path: If enabled, use DSA accelerator offloading for
> > +# certain memory operations. Enable DSA accelerator for zero
> > +# page detection offloading by setting the @zero-page-detection
> > +# to dsa-accel. This parameter defines the dsa device path, and
> > +# defaults to an empty list. (Since 9.2)
> > +#
> > # @direct-io: Open migration files with O_DIRECT when possible. This
> > # only has effect if the @mapped-ram capability is enabled.
> > # (Since 9.1)
> > @@ -855,7 +865,7 @@
> > 'cpu-throttle-initial', 'cpu-throttle-increment',
> > 'cpu-throttle-tailslow',
> > 'tls-creds', 'tls-hostname', 'tls-authz', 'max-bandwidth',
> > - 'avail-switchover-bandwidth', 'downtime-limit',
> > + 'avail-switchover-bandwidth', 'downtime-limit',
> > 'dsa-accel-path',
> > { 'name': 'x-checkpoint-delay', 'features': [ 'unstable' ] },
> > 'multifd-channels',
> > 'xbzrle-cache-size', 'max-postcopy-bandwidth',
> > @@ -1018,6 +1028,12 @@
> > # See description in @ZeroPageDetection. Default is 'multifd'.
> > # (since 9.0)
> > #
> > +# @dsa-accel-path: If enabled, use DSA accelerator offloading for
> > +# certain memory operations. Enable DSA accelerator for zero
> > +# page detection offloading by setting the @zero-page-detection
> > +# to dsa-accel. This parameter defines the dsa device path, and
> > +# defaults to an empty list. (Since 9.2)
> > +#
> > # @direct-io: Open migration files with O_DIRECT when possible. This
> > # only has effect if the @mapped-ram capability is enabled.
> > # (Since 9.1)
> > @@ -1063,7 +1079,8 @@
> > '*vcpu-dirty-limit': 'uint64',
> > '*mode': 'MigMode',
> > '*zero-page-detection': 'ZeroPageDetection',
> > - '*direct-io': 'bool' } }
> > + '*direct-io': 'bool',
> > + '*dsa-accel-path': [ 'str' ] } }
> >
> > ##
> > # @migrate-set-parameters:
> > @@ -1228,6 +1245,12 @@
> > # See description in @ZeroPageDetection. Default is 'multifd'.
> > # (since 9.0)
> > #
> > +# @dsa-accel-path: If enabled, use DSA accelerator offloading for
> > +# certain memory operations. Enable DSA accelerator for zero
> > +# page detection offloading by setting the @zero-page-detection
> > +# to dsa-accel. This parameter defines the dsa device path, and
> > +# defaults to an empty list. (Since 9.2)
> > +#
> > # @direct-io: Open migration files with O_DIRECT when possible. This
> > # only has effect if the @mapped-ram capability is enabled.
> > # (Since 9.1)
> > @@ -1270,7 +1293,8 @@
> > '*vcpu-dirty-limit': 'uint64',
> > '*mode': 'MigMode',
> > '*zero-page-detection': 'ZeroPageDetection',
> > - '*direct-io': 'bool' } }
> > + '*direct-io': 'bool',
> > + '*dsa-accel-path': [ 'str' ] } }
> >
> > ##
> > # @query-migrate-parameters:
> > diff --git a/util/dsa.c b/util/dsa.c
> > index cbaa47c360..eeede3c0c7 100644
> > --- a/util/dsa.c
> > +++ b/util/dsa.c
> > @@ -23,6 +23,7 @@
> > #include "qemu/bswap.h"
> > #include "qemu/error-report.h"
> > #include "qemu/rcu.h"
> > +#include <cpuid.h>
> >
> > #pragma GCC push_options
> > #pragma GCC target("enqcmd")
> > @@ -691,6 +692,36 @@ static void dsa_completion_thread_stop(void *opaque)
> > qemu_sem_destroy(&thread_context->sem_init_done);
> > }
> >
> > +/**
> > + * @brief Check if DSA is supported.
> > + *
> > + * @return True if DSA is supported, otherwise false.
> > + */
> > +bool qemu_dsa_is_supported(void)
> > +{
> > + /*
> > + * movdir64b is indicated by bit 28 of ecx in CPUID leaf 7, subleaf 0.
> > + * enqcmd is indicated by bit 29 of ecx in CPUID leaf 7, subleaf 0.
> > + * Doc:
> > https://cdrdv2-public.intel.com/819680/architecture-instruction-\
> > + * set-extensions-programming-reference.pdf
> > + */
> > + uint32_t eax, ebx, ecx, edx;
> > + bool movedirb_enabled;
> > + bool enqcmd_enabled;
> > +
> > + __get_cpuid_count(7, 0, &eax, &ebx, &ecx, &edx);
> > + movedirb_enabled = (ecx >> 28) & 0x1;
> > + if (!movedirb_enabled) {
> > + return false;
> > + }
> > + enqcmd_enabled = (ecx >> 29) & 0x1;
> > + if (!enqcmd_enabled) {
> > + return false;
> > + }
> > +
> > + return true;
> > +}
> > +
> > /**
> > * @brief Check if DSA is running.
> > *
> > --
> > Yichen Wang
> >
> --
> -----Open up your eyes, open up your mind, open up your code -------
> / Dr. David Alan Gilbert | Running GNU/Linux | Happy \
> \ dave @ treblig.org | | In Hex /
> \ _________________________|_____ http://www.treblig.org |_______/
