Messages in this thread Patch in this message | | | From | Shawn Wang <> | Subject | [PATCH v3] x86/resctrl: Clear staged_config[] before and after it is used | Date | Thu, 24 Nov 2022 20:42:37 +0800 |
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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: [ 6180.939345] unchecked MSR access error: WRMSR to 0xca0 (tried to write 0x00000000000007ff) at rIP: 0xffffffff82249142 (cat_wrmsr+0x32/0x60) [ 6180.951983] Call Trace: [ 6180.954516] <IRQ> [ 6180.956619] __flush_smp_call_function_queue+0x11d/0x170 [ 6180.962028] __sysvec_call_function+0x24/0xd0 [ 6180.966485] sysvec_call_function+0x89/0xc0 [ 6180.970760] </IRQ> [ 6180.972947] <TASK> [ 6180.975131] asm_sysvec_call_function+0x16/0x20
When creating a new resource control group, hardware will be configured by resctrl_arch_update_domains(): 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.
Fixes: 75408e43509ed ("x86/resctrl: Allow different CODE/DATA configurations to be staged") Cc: <stable@vger.kernel.org> Signed-off-by: Shawn Wang <shawnwang@linux.alibaba.com> Suggested-by: Xin Hao <xhao@linux.alibaba.com> --- 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/rdtgroup.c | 23 +++++++++++++++++++---- include/linux/resctrl.h | 2 ++ 3 files changed, 23 insertions(+), 9 deletions(-)
diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c index 1dafbdc5ac31..93d1f11a1f19 100644 --- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c +++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c @@ -374,7 +374,6 @@ 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; @@ -403,10 +402,7 @@ 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)); - } + resctrl_staged_configs_clear(); while ((tok = strsep(&buf, "\n")) != NULL) { resname = strim(strsep(&tok, ":")); @@ -451,6 +447,7 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of, } out: + resctrl_staged_configs_clear(); rdtgroup_kn_unlock(of->kn); cpus_read_unlock(); return ret ?: nbytes; diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c index e5a48f05e787..fa00eafd3cd8 100644 --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c @@ -2841,7 +2841,9 @@ static int rdtgroup_init_alloc(struct rdtgroup *rdtgrp) { struct resctrl_schema *s; struct rdt_resource *r; - int ret; + int ret = 0; + + resctrl_staged_configs_clear(); list_for_each_entry(s, &resctrl_schema_all, list) { r = s->res; @@ -2852,20 +2854,22 @@ 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: + resctrl_staged_configs_clear(); + return ret; } static int mkdir_rdt_prepare(struct kernfs_node *parent_kn, @@ -3380,6 +3384,17 @@ int resctrl_online_domain(struct rdt_resource *r, struct rdt_domain *d) return 0; } +void resctrl_staged_configs_clear(void) +{ + struct rdt_resource *r; + struct rdt_domain *dom; + + for_each_alloc_capable_rdt_resource(r) { + list_for_each_entry(dom, &r->domains, list) + memset(dom->staged_config, 0, sizeof(dom->staged_config)); + } +} + /* * rdtgroup_init - rdtgroup initialization * diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h index 0cf5b20c6ddf..2f7af447eaf2 100644 --- a/include/linux/resctrl.h +++ b/include/linux/resctrl.h @@ -250,6 +250,8 @@ int resctrl_arch_rmid_read(struct rdt_resource *r, struct rdt_domain *d, void resctrl_arch_reset_rmid(struct rdt_resource *r, struct rdt_domain *d, u32 rmid, enum resctrl_event_id eventid); +void resctrl_staged_configs_clear(void); + extern unsigned int resctrl_rmid_realloc_threshold; extern unsigned int resctrl_rmid_realloc_limit; -- 2.27.0
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