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Message-ID: <IA1PR11MB6097018866A49457E8D6F70A9BC79@IA1PR11MB6097.namprd11.prod.outlook.com>
Date: Wed, 18 Jan 2023 21:22:28 +0000
From: "Yu, Fenghua" <fenghua.yu@...el.com>
To: "Chatre, Reinette" <reinette.chatre@...el.com>,
"bp@...en8.de" <bp@...en8.de>,
"dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
"tglx@...utronix.de" <tglx@...utronix.de>,
"mingo@...hat.com" <mingo@...hat.com>,
"x86@...nel.org" <x86@...nel.org>
CC: "hpa@...or.com" <hpa@...or.com>,
"james.morse@....com" <james.morse@....com>,
"jamie@...iainc.com" <jamie@...iainc.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"shawnwang@...ux.alibaba.com" <shawnwang@...ux.alibaba.com>
Subject: RE: [PATCH v5] x86/resctrl: Clear staged_config[] before and after it
is used
> Chatre, Reinette <reinette.chatre@...el.com> writes
> Sent: Tuesday, January 17, 2023 1:15 PM
> To: Yu, Fenghua <fenghua.yu@...el.com>; bp@...en8.de;
> dave.hansen@...ux.intel.com; tglx@...utronix.de; mingo@...hat.com;
> x86@...nel.org
> Cc: hpa@...or.com; james.morse@....com; jamie@...iainc.com; linux-
> kernel@...r.kernel.org; shawnwang@...ux.alibaba.com; Chatre, Reinette
> <reinette.chatre@...el.com>
> Subject: [PATCH v5] x86/resctrl: Clear staged_config[] before and after it is used
>
> From: Shawn Wang <shawnwang@...ux.alibaba.com>
>
> As a temporary storage, staged_config[] in rdt_domain should be cleared before
> and after it is used. The stale value in staged_config[] could cause an MSR
> access error.
>
> Here is a reproducer on a system with 16 usable CLOSIDs for a 15-way L3 Cache
> (MBA should be disabled if the number of CLOSIDs for MB is less than
> 16.) :
> mount -t resctrl resctrl -o cdp /sys/fs/resctrl
> mkdir /sys/fs/resctrl/p{1..7}
> umount /sys/fs/resctrl/
> mount -t resctrl resctrl /sys/fs/resctrl
> mkdir /sys/fs/resctrl/p{1..8}
>
> An error occurs when creating resource group named p8:
> unchecked MSR access error: WRMSR to 0xca0 (tried to write
> 0x00000000000007ff) at rIP: 0xffffffff82249142 (cat_wrmsr+0x32/0x60)
> Call Trace:
> <IRQ>
> __flush_smp_call_function_queue+0x11d/0x170
> __sysvec_call_function+0x24/0xd0
> sysvec_call_function+0x89/0xc0
> </IRQ>
> <TASK>
> asm_sysvec_call_function+0x16/0x20
>
> When creating a new resource control group, hardware will be configured by
> the following process:
> rdtgroup_mkdir()
> rdtgroup_mkdir_ctrl_mon()
> rdtgroup_init_alloc()
> resctrl_arch_update_domains()
>
> resctrl_arch_update_domains() iterates and updates all resctrl_conf_type whose
> have_new_ctrl is true. Since staged_config[] holds the same values as when CDP
> was enabled, it will continue to update the CDP_CODE and CDP_DATA
> configurations. When group p8 is created, get_config_index() called in
> resctrl_arch_update_domains() will return 16 and 17 as the CLOSIDs for
> CDP_CODE and CDP_DATA, which will be translated to an invalid register -
> 0xca0 in this scenario.
>
> Fix it by clearing staged_config[] before and after it is used.
>
> [reinette: re-order commit tags]
>
> Fixes: 75408e43509e ("x86/resctrl: Allow different CODE/DATA configurations
> to be staged")
> Suggested-by: Xin Hao <xhao@...ux.alibaba.com>
> Signed-off-by: Shawn Wang <shawnwang@...ux.alibaba.com>
> Signed-off-by: Reinette Chatre <reinette.chatre@...el.com>
> Tested-by: Reinette Chatre <reinette.chatre@...el.com>
> Cc: <stable@...r.kernel.org>
> ---
> Changes since v4:
> - Essentially a resubmit of v4, changes limited to commit tags.
> - v4: https://lore.kernel.org/lkml/20221209024436.22170-1-
> shawnwang@...ux.alibaba.com/
> - No changes to patch.
> - Only change in changelog is re-ordering of commit tags.
> - Add Reinette's Tested-by, but change the Reviewed-by to Signed-off-by
> because of the change in hands of this submission.
>
> Changes since v3:
> - Update the commit message suggested by Reiniette Chatre.
> - Rename resctrl_staged_configs_clear() to rdt_staged_configs_clear().
> - Move rdt_staged_configs_clear() to arch/x86/kernel/cpu/resctrl/internal.h.
>
> Changes since v2:
> - Update the commit message suggested by Reiniette Chatre.
> - Make the clearing work more robust.
>
> Changes since v1:
> - Move the clearing from schemata_list_destroy() to
> resctrl_arch_update_domains().
> - Update the commit message suggested by Reiniette Chatre.
> - Add stable tag suggested by James Morse.
>
> arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 7 ++-----
> arch/x86/kernel/cpu/resctrl/internal.h | 1 +
> arch/x86/kernel/cpu/resctrl/rdtgroup.c | 25 +++++++++++++++++++----
> 3 files changed, 24 insertions(+), 9 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> index 1df0e3262bca..bcdc679dad4e 100644
> --- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> +++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> @@ -373,7 +373,6 @@ ssize_t rdtgroup_schemata_write(struct
> kernfs_open_file *of, {
> struct resctrl_schema *s;
> struct rdtgroup *rdtgrp;
> - struct rdt_domain *dom;
> struct rdt_resource *r;
> char *tok, *resname;
> int ret = 0;
> @@ -402,10 +401,7 @@ ssize_t rdtgroup_schemata_write(struct
> kernfs_open_file *of,
> goto out;
> }
>
> - list_for_each_entry(s, &resctrl_schema_all, list) {
> - list_for_each_entry(dom, &s->res->domains, list)
> - memset(dom->staged_config, 0, sizeof(dom-
> >staged_config));
> - }
> + rdt_staged_configs_clear();
>
> while ((tok = strsep(&buf, "\n")) != NULL) {
> resname = strim(strsep(&tok, ":"));
> @@ -450,6 +446,7 @@ ssize_t rdtgroup_schemata_write(struct
> kernfs_open_file *of,
> }
>
> out:
> + rdt_staged_configs_clear();
> rdtgroup_kn_unlock(of->kn);
> cpus_read_unlock();
> return ret ?: nbytes;
> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h
> b/arch/x86/kernel/cpu/resctrl/internal.h
> index 5ebd28e6aa0c..f43eb7340ca5 100644
> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> @@ -527,5 +527,6 @@ bool has_busy_rmid(struct rdt_resource *r, struct
> rdt_domain *d); void __check_limbo(struct rdt_domain *d, bool force_free);
> void rdt_domain_reconfigure_cdp(struct rdt_resource *r); void __init
> thread_throttle_mode_init(void);
> +void rdt_staged_configs_clear(void);
>
> #endif /* _ASM_X86_RESCTRL_INTERNAL_H */ diff --git
> a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index 5993da21d822..41e89fc49d77 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -78,6 +78,19 @@ void rdt_last_cmd_printf(const char *fmt, ...)
> va_end(ap);
> }
>
> +void rdt_staged_configs_clear(void)
> +{
> + struct rdt_resource *r;
> + struct rdt_domain *dom;
> +
> + lockdep_assert_held(&rdtgroup_mutex);
> +
> + for_each_alloc_capable_rdt_resource(r) {
> + list_for_each_entry(dom, &r->domains, list)
> + memset(dom->staged_config, 0, sizeof(dom-
> >staged_config));
> + }
> +}
> +
> /*
> * Trivial allocator for CLOSIDs. Since h/w only supports a small number,
> * we can keep a bitmap of free CLOSIDs in a single integer.
> @@ -2851,7 +2864,9 @@ static int rdtgroup_init_alloc(struct rdtgroup *rdtgrp)
> {
> struct resctrl_schema *s;
> struct rdt_resource *r;
> - int ret;
> + int ret = 0;
> +
> + rdt_staged_configs_clear();
>
> list_for_each_entry(s, &resctrl_schema_all, list) {
> r = s->res;
> @@ -2862,20 +2877,22 @@ static int rdtgroup_init_alloc(struct rdtgroup
> *rdtgrp)
> } else {
> ret = rdtgroup_init_cat(s, rdtgrp->closid);
> if (ret < 0)
> - return ret;
> + goto out;
> }
>
> ret = resctrl_arch_update_domains(r, rdtgrp->closid);
> if (ret < 0) {
> rdt_last_cmd_puts("Failed to initialize allocations\n");
> - return ret;
> + goto out;
> }
>
> }
>
> rdtgrp->mode = RDT_MODE_SHAREABLE;
>
> - return 0;
> +out:
> + rdt_staged_configs_clear();
> + return ret;
> }
>
> static int mkdir_rdt_prepare(struct kernfs_node *parent_kn,
> --
> 2.34.1
Reviewed-by: Fenghua Yu <fenghua.yu@...el.com>
Thanks.
-Fenghua
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