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Message-ID: <072e82c2-97c2-429f-a0e3-10eb0bd00b1e@marvell.com>
Date: Fri, 7 Mar 2025 15:47:14 +0530
From: Amit Singh Tomar <amitsinght@...vell.com>
To: James Morse <james.morse@....com>, x86@...nel.org,
linux-kernel@...r.kernel.org
Cc: Reinette Chatre <reinette.chatre@...el.com>,
Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
Borislav Petkov <bp@...en8.de>, H Peter Anvin <hpa@...or.com>,
Babu Moger <Babu.Moger@....com>, shameerali.kolothum.thodi@...wei.com,
D Scott Phillips OS <scott@...amperecomputing.com>,
carl@...amperecomputing.com, lcherian@...vell.com,
bobo.shaobowang@...wei.com, tan.shaopeng@...itsu.com,
baolin.wang@...ux.alibaba.com, Jamie Iles <quic_jiles@...cinc.com>,
Xin Hao <xhao@...ux.alibaba.com>, peternewman@...gle.com,
dfustini@...libre.com, David Hildenbrand <david@...hat.com>,
Rex Nie <rex.nie@...uarmicro.com>, Dave Martin <dave.martin@....com>,
Koba Ko <kobak@...dia.com>,
Shanker Donthineni <sdonthineni@...dia.com>, fenghuay@...dia.com
Subject: [PATCH v7 37/49] x86/resctrl: Expand the width of dom_id by replacing
mon_data_bits
Hi James,
> MPAM platforms retrieve the cache-id property from the ACPI PPTT table.
> The cache-id field is 32 bits wide. Under resctrl, the cache-id becomes
> the domain-id, and is packed into the mon_data_bits union bitfield.
> The width of cache-id in this field is 14 bits.
>
> Expanding the union would break 32bit x86 platforms as this union is
> stored as the kernfs kn->priv pointer. This saved allocating memory
> for the priv data storage.
>
> The firmware on MPAM platforms have used the PPTT cache-id field to
> expose the interconnect's id for the cache, which is sparse and uses
> more than 14 bits. Use of this id is to enable PCIe direct cache
> injection hints. Using this feature with VFIO means the value provided
> by the ACPI table should be exposed to user-space.
>
> To support cache-id values greater than 14 bits, convert the
> mon_data_bits union to a structure. This is allocated for the default
> control group when the kernfs event files are created, and free'd when
> the monitor directory is rmdir'd when the domain goes offline.
> All other control and monitor groups lookup the struct mon_data allocated
> for the default control group, and use this.
> This simplifies the lifecycle of this structure as the default control
> group cannot be rmdir()d by user-space, so only needs to consider
> domain-offline, which removes all the event files corresponding to a
> domain while holding rdtgroup_mutex - which prevents concurrent
> readers. mkdir_mondata_subdir_allrdtgrp() must special case the default
> control group to ensure it is created first.
>
> Signed-off-by: James Morse <james.morse@....com>
> ---
> Previously the MPAM tree repainted the cache-id to compact them,
> argue-ing there was no other user. With VFIO use of this PCIe feature,
> this is no longer an option.
>
> Changes since v6:
> * Added the get/put helpers.
> * Special case the creation of the mondata files for the default control
> group.
> * Removed wording about files living longer than expected, the corresponding
> error handling is wrapped in WARN_ON_ONCE() as this indicates a bug.
> ---
> arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 19 +--
> arch/x86/kernel/cpu/resctrl/internal.h | 37 +++---
> arch/x86/kernel/cpu/resctrl/monitor.c | 3 +
> arch/x86/kernel/cpu/resctrl/rdtgroup.c | 142 ++++++++++++++++++++--
> 4 files changed, 162 insertions(+), 39 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> index 0a0ac5f6112e..159972c3fe73 100644
> --- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> +++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> @@ -667,7 +667,7 @@ int rdtgroup_mondata_show(struct seq_file *m, void *arg)
> u32 resid, evtid, domid;
> struct rdtgroup *rdtgrp;
> struct rdt_resource *r;
> - union mon_data_bits md;
> + struct mon_data *md;
> int ret = 0;
>
> rdtgrp = rdtgroup_kn_lock_live(of->kn);
> @@ -676,17 +676,22 @@ int rdtgroup_mondata_show(struct seq_file *m, void *arg)
> goto out;
> }
>
> - md.priv = of->kn->priv;
> - resid = md.u.rid;
> - domid = md.u.domid;
> - evtid = md.u.evtid;
> + md = of->kn->priv;
> + if (WARN_ON_ONCE(!md)) {
> + ret = -EIO;
> + goto out;
> + }
> +
> + resid = md->rid;
> + domid = md->domid;
> + evtid = md->evtid;
> r = resctrl_arch_get_resource(resid);
>
> - if (md.u.sum) {
> + if (md->sum) {
> /*
> * This file requires summing across all domains that share
> * the L3 cache id that was provided in the "domid" field of the
> - * mon_data_bits union. Search all domains in the resource for
> + * struct mon_data. Search all domains in the resource for
> * one that matches this cache id.
> */
> list_for_each_entry(d, &r->mon_domains, hdr.list) {
> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
> index 32ed9aeffb90..16c1a391d012 100644
> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> @@ -103,27 +103,24 @@ struct mon_evt {
> };
>
> /**
> - * union mon_data_bits - Monitoring details for each event file.
> - * @priv: Used to store monitoring event data in @u
> - * as kernfs private data.
> - * @u.rid: Resource id associated with the event file.
> - * @u.evtid: Event id associated with the event file.
> - * @u.sum: Set when event must be summed across multiple
> - * domains.
> - * @u.domid: When @u.sum is zero this is the domain to which
> - * the event file belongs. When @sum is one this
> - * is the id of the L3 cache that all domains to be
> - * summed share.
> - * @u: Name of the bit fields struct.
> + * struct mon_data - Monitoring details for each event file.
> + * @rid: Resource id associated with the event file.
> + * @evtid: Event id associated with the event file.
> + * @sum: Set when event must be summed across multiple
> + * domains.
> + * @domid: When @sum is zero this is the domain to which
> + * the event file belongs. When @sum is one this
> + * is the id of the L3 cache that all domains to be
> + * summed share.
> + *
> + * Stored in the kernfs kn->priv field, readers and writers must hold
> + * rdtgroup_mutex.
> */
> -union mon_data_bits {
> - void *priv;
> - struct {
> - unsigned int rid : 10;
> - enum resctrl_event_id evtid : 7;
> - unsigned int sum : 1;
> - unsigned int domid : 14;
> - } u;
> +struct mon_data {
> + unsigned int rid;
> + enum resctrl_event_id evtid;
> + unsigned int sum;
> + unsigned int domid;
> };
>
> /**
> diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
> index 73e3fe4f4c87..5bf67b429dd3 100644
> --- a/arch/x86/kernel/cpu/resctrl/monitor.c
> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
> @@ -1096,6 +1096,9 @@ static struct mon_evt mbm_local_event = {
> * Note that MBM events are also part of RDT_RESOURCE_L3 resource
> * because as per the SDM the total and local memory bandwidth
> * are enumerated as part of L3 monitoring.
> + *
> + * mon_put_default_kn_priv_all() also assumes monitor events are only supported
> + * on the L3 resource.
> */
> static void l3_mon_evt_init(struct rdt_resource *r)
> {
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index aecd3fa734cd..443635d195f0 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -3114,6 +3114,110 @@ static struct file_system_type rdt_fs_type = {
> .kill_sb = rdt_kill_sb,
> };
>
> +/**
> + * mon_get_default_kn_priv() - Get the mon_data priv data for this event from
> + * the default control group.
> + * Called when monitor event files are created for a domain.
> + * When called with the default control group, the structure will be allocated.
> + * This happens at mount time, before other control or monitor groups are
> + * created.
> + * This simplifies the lifetime management for rmdir() versus domain-offline
> + * as the default control group lives forever, and only one group needs to be
> + * special cased.
> + *
> + * @r: The resource for the event type being created.
> + * @d: The domain for the event type being created.
> + * @mevt: The event type being created.
> + * @rdtgrp: The rdtgroup for which the monitor file is being created,
> + * used to determine if this is the default control group.
> + * @do_sum: Whether the SNC sub-numa node monitors are being created.
> + */
> +static struct mon_data *mon_get_default_kn_priv(struct rdt_resource *r,
> + struct rdt_mon_domain *d,
> + struct mon_evt *mevt,
> + struct rdtgroup *rdtgrp,
> + bool do_sum)
> +{
> + struct kernfs_node *kn_dom, *kn_evt;
> + struct mon_data *priv;
> + bool snc_mode;
> + char name[32];
> +
> + lockdep_assert_held(&rdtgroup_mutex);
> +
> + snc_mode = r->mon_scope == RESCTRL_L3_NODE;
> + if (!do_sum)
> + sprintf(name, "mon_%s_%02d", r->name, snc_mode ? d->ci->id : d->hdr.id);
This change triggered a minor report during compilation.
fs/resctrl/rdtgroup.c: In function ‘mon_get_default_kn_priv’:
fs/resctrl/rdtgroup.c:2931:28: warning: format ‘%d’ expects argument of
type ‘int’, but argument 4 has type ‘long unsigned int’ [-Wformat=]
2931 | sprintf(name, "mon_%s_%02d", r->name, snc_mode ? d->ci->id :
d->hdr.id);
| ~~~^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| | |
| int long unsigned int
| %02ld
> + else
> + sprintf(name, "mon_sub_%s_%02d", r->name, d->hdr.id);
> +
> + kn_dom = kernfs_find_and_get(kn_mondata, name);
> + if (!kn_dom)
> + return NULL;
> +
> + kn_evt = kernfs_find_and_get(kn_dom, mevt->name);
> +
> + /* Is this the creation of the default groups monitor files? */
> + if (!kn_evt && rdtgrp == &rdtgroup_default) {
> + priv = kzalloc(sizeof(*priv), GFP_KERNEL);
> + if (!priv)
> + return NULL;
> + priv->rid = r->rid;
> + priv->domid = do_sum ? d->ci->id : d->hdr.id;
> + priv->sum = do_sum;
> + priv->evtid = mevt->evtid;
> + return priv;
> + }
> +
> + if (!kn_evt)
> + return NULL;
> +
> + return kn_evt->priv;
> +}
> +
> +/**
> + * mon_put_default_kn_priv_all() - Potentially free the mon_data priv data for
> + * all events from the default control group.
> + * Put the mon_data priv data for all events for a particular domain.
> + * When called with the default control group, the priv structure previously
> + * allocated will be kfree()d. This should only be done as part of taking a
> + * domain offline.
> + * Only a domain offline will 'rmdir' monitor files in the default control
> + * group. After domain offline releases rdtgrp_mutex, all references will
> + * have been removed.
> + *
> + * @rdtgrp: The rdtgroup for which the monitor files are being removed,
> + * used to determine if this is the default control group.
> + * @name: The name of the domain or SNC sub-numa domain which is being
> + * taken offline.
> + */
> +static void mon_put_default_kn_priv_all(struct rdtgroup *rdtgrp, char *name)
> +{
> + struct rdt_resource *r = resctrl_arch_get_resource(RDT_RESOURCE_L3);
> + struct kernfs_node *kn_dom, *kn_evt;
> + struct mon_evt *mevt;
> +
> + lockdep_assert_held(&rdtgroup_mutex);
> +
> + if (rdtgrp != &rdtgroup_default)
> + return;
> +
> + kn_dom = kernfs_find_and_get(kn_mondata, name);
> + if (!kn_dom)
> + return;
> +
> + list_for_each_entry(mevt, &r->evt_list, list) {
> + kn_evt = kernfs_find_and_get(kn_dom, mevt->name);
> + if (!kn_evt)
> + continue;
> + if (!kn_evt->priv)
> + continue;
> +
> + kfree(kn_evt->priv);
> + kn_evt->priv = NULL;
> + }
> +}
> +
> static int mon_addfile(struct kernfs_node *parent_kn, const char *name,
> void *priv)
> {
> @@ -3135,19 +3239,25 @@ static int mon_addfile(struct kernfs_node *parent_kn, const char *name,
> return ret;
> }
>
> -static void mon_rmdir_one_subdir(struct kernfs_node *pkn, char *name, char *subname)
> +static void mon_rmdir_one_subdir(struct rdtgroup *rdtgrp, char *name, char *subname)
> {
> + struct kernfs_node *pkn = rdtgrp->mon.mon_data_kn;
> struct kernfs_node *kn;
>
> kn = kernfs_find_and_get(pkn, name);
> if (!kn)
> return;
> +
> + mon_put_default_kn_priv_all(rdtgrp, name);
> +
> kernfs_put(kn);
>
> - if (kn->dir.subdirs <= 1)
> + if (kn->dir.subdirs <= 1) {
> kernfs_remove(kn);
> - else
> + } else {
> + mon_put_default_kn_priv_all(rdtgrp, subname);
> kernfs_remove_by_name(kn, subname);
> + }
> }
>
> /*
> @@ -3170,10 +3280,10 @@ static void rmdir_mondata_subdir_allrdtgrp(struct rdt_resource *r,
> sprintf(subname, "mon_sub_%s_%02d", r->name, d->hdr.id);
>
> list_for_each_entry(prgrp, &rdt_all_groups, rdtgroup_list) {
> - mon_rmdir_one_subdir(prgrp->mon.mon_data_kn, name, subname);
> + mon_rmdir_one_subdir(prgrp, name, subname);
>
> list_for_each_entry(crgrp, &prgrp->mon.crdtgrp_list, mon.crdtgrp_list)
> - mon_rmdir_one_subdir(crgrp->mon.mon_data_kn, name, subname);
> + mon_rmdir_one_subdir(crgrp, name, subname);
> }
> }
>
> @@ -3182,19 +3292,19 @@ static int mon_add_all_files(struct kernfs_node *kn, struct rdt_mon_domain *d,
> bool do_sum)
> {
> struct rmid_read rr = {0};
> - union mon_data_bits priv;
> + struct mon_data *priv;
> struct mon_evt *mevt;
> int ret;
>
> if (WARN_ON(list_empty(&r->evt_list)))
> return -EPERM;
>
> - priv.u.rid = r->rid;
> - priv.u.domid = do_sum ? d->ci->id : d->hdr.id;
> - priv.u.sum = do_sum;
> list_for_each_entry(mevt, &r->evt_list, list) {
> - priv.u.evtid = mevt->evtid;
> - ret = mon_addfile(kn, mevt->name, priv.priv);
> + priv = mon_get_default_kn_priv(r, d, mevt, prgrp, do_sum);
> + if (WARN_ON_ONCE(!priv))
> + return -EINVAL;
> +
> + ret = mon_addfile(kn, mevt->name, priv);
> if (ret)
> return ret;
>
> @@ -3274,9 +3384,17 @@ static void mkdir_mondata_subdir_allrdtgrp(struct rdt_resource *r,
> struct rdtgroup *prgrp, *crgrp;
> struct list_head *head;
>
> + /*
> + * During domain-online create the default control group first
> + * so that mon_get_default_kn_priv() can find the allocated structure
> + * on subsequent calls.
> + */
> + mkdir_mondata_subdir(kn_mondata, d, r, &rdtgroup_default);
> +
> list_for_each_entry(prgrp, &rdt_all_groups, rdtgroup_list) {
> parent_kn = prgrp->mon.mon_data_kn;
> - mkdir_mondata_subdir(parent_kn, d, r, prgrp);
> + if (prgrp != &rdtgroup_default)
> + mkdir_mondata_subdir(parent_kn, d, r, prgrp);
>
> head = &prgrp->mon.crdtgrp_list;
> list_for_each_entry(crgrp, head, mon.crdtgrp_list) {
> --
> 2.39.5
>
On 3/1/2025 1:29 AM, James Morse wrote:
> MPAM platforms retrieve the cache-id property from the ACPI PPTT
> table. The cache-id field is 32 bits wide. Under resctrl, the cache-id
> becomes the domain-id, and is packed into the mon_data_bits union
> bitfield. The width of cache-id in this
>
> MPAM platforms retrieve the cache-id property from the ACPI PPTT table.
> The cache-id field is 32 bits wide. Under resctrl, the cache-id becomes
> the domain-id, and is packed into the mon_data_bits union bitfield.
> The width of cache-id in this field is 14 bits.
>
> Expanding the union would break 32bit x86 platforms as this union is
> stored as the kernfs kn->priv pointer. This saved allocating memory
> for the priv data storage.
>
> The firmware on MPAM platforms have used the PPTT cache-id field to
> expose the interconnect's id for the cache, which is sparse and uses
> more than 14 bits. Use of this id is to enable PCIe direct cache
> injection hints. Using this feature with VFIO means the value provided
> by the ACPI table should be exposed to user-space.
>
> To support cache-id values greater than 14 bits, convert the
> mon_data_bits union to a structure. This is allocated for the default
> control group when the kernfs event files are created, and free'd when
> the monitor directory is rmdir'd when the domain goes offline.
> All other control and monitor groups lookup the struct mon_data allocated
> for the default control group, and use this.
> This simplifies the lifecycle of this structure as the default control
> group cannot be rmdir()d by user-space, so only needs to consider
> domain-offline, which removes all the event files corresponding to a
> domain while holding rdtgroup_mutex - which prevents concurrent
> readers. mkdir_mondata_subdir_allrdtgrp() must special case the default
> control group to ensure it is created first.
>
> Signed-off-by: James Morse <james.morse@....com>
> ---
> Previously the MPAM tree repainted the cache-id to compact them,
> argue-ing there was no other user. With VFIO use of this PCIe feature,
> this is no longer an option.
>
> Changes since v6:
> * Added the get/put helpers.
> * Special case the creation of the mondata files for the default control
> group.
> * Removed wording about files living longer than expected, the corresponding
> error handling is wrapped in WARN_ON_ONCE() as this indicates a bug.
> ---
> arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 19 +--
> arch/x86/kernel/cpu/resctrl/internal.h | 37 +++---
> arch/x86/kernel/cpu/resctrl/monitor.c | 3 +
> arch/x86/kernel/cpu/resctrl/rdtgroup.c | 142 ++++++++++++++++++++--
> 4 files changed, 162 insertions(+), 39 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> index 0a0ac5f6112e..159972c3fe73 100644
> --- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> +++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> @@ -667,7 +667,7 @@ int rdtgroup_mondata_show(struct seq_file *m, void *arg)
> u32 resid, evtid, domid;
> struct rdtgroup *rdtgrp;
> struct rdt_resource *r;
> - union mon_data_bits md;
> + struct mon_data *md;
> int ret = 0;
>
> rdtgrp = rdtgroup_kn_lock_live(of->kn);
> @@ -676,17 +676,22 @@ int rdtgroup_mondata_show(struct seq_file *m, void *arg)
> goto out;
> }
>
> - md.priv = of->kn->priv;
> - resid = md.u.rid;
> - domid = md.u.domid;
> - evtid = md.u.evtid;
> + md = of->kn->priv;
> + if (WARN_ON_ONCE(!md)) {
> + ret = -EIO;
> + goto out;
> + }
> +
> + resid = md->rid;
> + domid = md->domid;
> + evtid = md->evtid;
> r = resctrl_arch_get_resource(resid);
>
> - if (md.u.sum) {
> + if (md->sum) {
> /*
> * This file requires summing across all domains that share
> * the L3 cache id that was provided in the "domid" field of the
> - * mon_data_bits union. Search all domains in the resource for
> + * struct mon_data. Search all domains in the resource for
> * one that matches this cache id.
> */
> list_for_each_entry(d, &r->mon_domains, hdr.list) {
> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
> index 32ed9aeffb90..16c1a391d012 100644
> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> @@ -103,27 +103,24 @@ struct mon_evt {
> };
>
> /**
> - * union mon_data_bits - Monitoring details for each event file.
> - * @priv: Used to store monitoring event data in @u
> - * as kernfs private data.
> - * @u.rid: Resource id associated with the event file.
> - * @u.evtid: Event id associated with the event file.
> - * @u.sum: Set when event must be summed across multiple
> - * domains.
> - * @u.domid: When @u.sum is zero this is the domain to which
> - * the event file belongs. When @sum is one this
> - * is the id of the L3 cache that all domains to be
> - * summed share.
> - * @u: Name of the bit fields struct.
> + * struct mon_data - Monitoring details for each event file.
> + * @rid: Resource id associated with the event file.
> + * @evtid: Event id associated with the event file.
> + * @sum: Set when event must be summed across multiple
> + * domains.
> + * @domid: When @sum is zero this is the domain to which
> + * the event file belongs. When @sum is one this
> + * is the id of the L3 cache that all domains to be
> + * summed share.
> + *
> + * Stored in the kernfs kn->priv field, readers and writers must hold
> + * rdtgroup_mutex.
> */
> -union mon_data_bits {
> - void *priv;
> - struct {
> - unsigned int rid : 10;
> - enum resctrl_event_id evtid : 7;
> - unsigned int sum : 1;
> - unsigned int domid : 14;
> - } u;
> +struct mon_data {
> + unsigned int rid;
> + enum resctrl_event_id evtid;
> + unsigned int sum;
> + unsigned int domid;
> };
>
> /**
> diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
> index 73e3fe4f4c87..5bf67b429dd3 100644
> --- a/arch/x86/kernel/cpu/resctrl/monitor.c
> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
> @@ -1096,6 +1096,9 @@ static struct mon_evt mbm_local_event = {
> * Note that MBM events are also part of RDT_RESOURCE_L3 resource
> * because as per the SDM the total and local memory bandwidth
> * are enumerated as part of L3 monitoring.
> + *
> + * mon_put_default_kn_priv_all() also assumes monitor events are only supported
> + * on the L3 resource.
> */
> static void l3_mon_evt_init(struct rdt_resource *r)
> {
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index aecd3fa734cd..443635d195f0 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -3114,6 +3114,110 @@ static struct file_system_type rdt_fs_type = {
> .kill_sb = rdt_kill_sb,
> };
>
> +/**
> + * mon_get_default_kn_priv() - Get the mon_data priv data for this event from
> + * the default control group.
> + * Called when monitor event files are created for a domain.
> + * When called with the default control group, the structure will be allocated.
> + * This happens at mount time, before other control or monitor groups are
> + * created.
> + * This simplifies the lifetime management for rmdir() versus domain-offline
> + * as the default control group lives forever, and only one group needs to be
> + * special cased.
> + *
> + * @r: The resource for the event type being created.
> + * @d: The domain for the event type being created.
> + * @mevt: The event type being created.
> + * @rdtgrp: The rdtgroup for which the monitor file is being created,
> + * used to determine if this is the default control group.
> + * @do_sum: Whether the SNC sub-numa node monitors are being created.
> + */
> +static struct mon_data *mon_get_default_kn_priv(struct rdt_resource *r,
> + struct rdt_mon_domain *d,
> + struct mon_evt *mevt,
> + struct rdtgroup *rdtgrp,
> + bool do_sum)
> +{
> + struct kernfs_node *kn_dom, *kn_evt;
> + struct mon_data *priv;
> + bool snc_mode;
> + char name[32];
> +
> + lockdep_assert_held(&rdtgroup_mutex);
> +
> + snc_mode = r->mon_scope == RESCTRL_L3_NODE;
> + if (!do_sum)
> + sprintf(name, "mon_%s_%02d", r->name, snc_mode ? d->ci->id : d->hdr.id);
> + else
> + sprintf(name, "mon_sub_%s_%02d", r->name, d->hdr.id);
> +
> + kn_dom = kernfs_find_and_get(kn_mondata, name);
> + if (!kn_dom)
> + return NULL;
> +
> + kn_evt = kernfs_find_and_get(kn_dom, mevt->name);
> +
> + /* Is this the creation of the default groups monitor files? */
> + if (!kn_evt && rdtgrp == &rdtgroup_default) {
> + priv = kzalloc(sizeof(*priv), GFP_KERNEL);
> + if (!priv)
> + return NULL;
> + priv->rid = r->rid;
> + priv->domid = do_sum ? d->ci->id : d->hdr.id;
> + priv->sum = do_sum;
> + priv->evtid = mevt->evtid;
> + return priv;
> + }
> +
> + if (!kn_evt)
> + return NULL;
> +
> + return kn_evt->priv;
> +}
> +
> +/**
> + * mon_put_default_kn_priv_all() - Potentially free the mon_data priv data for
> + * all events from the default control group.
> + * Put the mon_data priv data for all events for a particular domain.
> + * When called with the default control group, the priv structure previously
> + * allocated will be kfree()d. This should only be done as part of taking a
> + * domain offline.
> + * Only a domain offline will 'rmdir' monitor files in the default control
> + * group. After domain offline releases rdtgrp_mutex, all references will
> + * have been removed.
> + *
> + * @rdtgrp: The rdtgroup for which the monitor files are being removed,
> + * used to determine if this is the default control group.
> + * @name: The name of the domain or SNC sub-numa domain which is being
> + * taken offline.
> + */
> +static void mon_put_default_kn_priv_all(struct rdtgroup *rdtgrp, char *name)
> +{
> + struct rdt_resource *r = resctrl_arch_get_resource(RDT_RESOURCE_L3);
> + struct kernfs_node *kn_dom, *kn_evt;
> + struct mon_evt *mevt;
> +
> + lockdep_assert_held(&rdtgroup_mutex);
> +
> + if (rdtgrp != &rdtgroup_default)
> + return;
> +
> + kn_dom = kernfs_find_and_get(kn_mondata, name);
> + if (!kn_dom)
> + return;
> +
> + list_for_each_entry(mevt, &r->evt_list, list) {
> + kn_evt = kernfs_find_and_get(kn_dom, mevt->name);
> + if (!kn_evt)
> + continue;
> + if (!kn_evt->priv)
> + continue;
> +
> + kfree(kn_evt->priv);
> + kn_evt->priv = NULL;
> + }
> +}
> +
> static int mon_addfile(struct kernfs_node *parent_kn, const char *name,
> void *priv)
> {
> @@ -3135,19 +3239,25 @@ static int mon_addfile(struct kernfs_node *parent_kn, const char *name,
> return ret;
> }
>
> -static void mon_rmdir_one_subdir(struct kernfs_node *pkn, char *name, char *subname)
> +static void mon_rmdir_one_subdir(struct rdtgroup *rdtgrp, char *name, char *subname)
> {
> + struct kernfs_node *pkn = rdtgrp->mon.mon_data_kn;
> struct kernfs_node *kn;
>
> kn = kernfs_find_and_get(pkn, name);
> if (!kn)
> return;
> +
> + mon_put_default_kn_priv_all(rdtgrp, name);
> +
> kernfs_put(kn);
>
> - if (kn->dir.subdirs <= 1)
> + if (kn->dir.subdirs <= 1) {
> kernfs_remove(kn);
> - else
> + } else {
> + mon_put_default_kn_priv_all(rdtgrp, subname);
> kernfs_remove_by_name(kn, subname);
> + }
> }
>
> /*
> @@ -3170,10 +3280,10 @@ static void rmdir_mondata_subdir_allrdtgrp(struct rdt_resource *r,
> sprintf(subname, "mon_sub_%s_%02d", r->name, d->hdr.id);
>
> list_for_each_entry(prgrp, &rdt_all_groups, rdtgroup_list) {
> - mon_rmdir_one_subdir(prgrp->mon.mon_data_kn, name, subname);
> + mon_rmdir_one_subdir(prgrp, name, subname);
>
> list_for_each_entry(crgrp, &prgrp->mon.crdtgrp_list, mon.crdtgrp_list)
> - mon_rmdir_one_subdir(crgrp->mon.mon_data_kn, name, subname);
> + mon_rmdir_one_subdir(crgrp, name, subname);
> }
> }
>
> @@ -3182,19 +3292,19 @@ static int mon_add_all_files(struct kernfs_node *kn, struct rdt_mon_domain *d,
> bool do_sum)
> {
> struct rmid_read rr = {0};
> - union mon_data_bits priv;
> + struct mon_data *priv;
> struct mon_evt *mevt;
> int ret;
>
> if (WARN_ON(list_empty(&r->evt_list)))
> return -EPERM;
>
> - priv.u.rid = r->rid;
> - priv.u.domid = do_sum ? d->ci->id : d->hdr.id;
> - priv.u.sum = do_sum;
> list_for_each_entry(mevt, &r->evt_list, list) {
> - priv.u.evtid = mevt->evtid;
> - ret = mon_addfile(kn, mevt->name, priv.priv);
> + priv = mon_get_default_kn_priv(r, d, mevt, prgrp, do_sum);
> + if (WARN_ON_ONCE(!priv))
> + return -EINVAL;
> +
> + ret = mon_addfile(kn, mevt->name, priv);
> if (ret)
> return ret;
>
> @@ -3274,9 +3384,17 @@ static void mkdir_mondata_subdir_allrdtgrp(struct rdt_resource *r,
> struct rdtgroup *prgrp, *crgrp;
> struct list_head *head;
>
> + /*
> + * During domain-online create the default control group first
> + * so that mon_get_default_kn_priv() can find the allocated structure
> + * on subsequent calls.
> + */
> + mkdir_mondata_subdir(kn_mondata, d, r, &rdtgroup_default);
> +
> list_for_each_entry(prgrp, &rdt_all_groups, rdtgroup_list) {
> parent_kn = prgrp->mon.mon_data_kn;
> - mkdir_mondata_subdir(parent_kn, d, r, prgrp);
> + if (prgrp != &rdtgroup_default)
> + mkdir_mondata_subdir(parent_kn, d, r, prgrp);
>
> head = &prgrp->mon.crdtgrp_list;
> list_for_each_entry(crgrp, head, mon.crdtgrp_list) {
> --
> 2.39.5
>
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