x86/resctrl: Clear staged_config[] before and after it is used

commit 47663e841f12cbb0647750f5c581151b4a769a4d upstream.

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: ef07a1531c27 ("x86/resctrl: Allow different CODE/DATA configurations to be staged")
Suggested-by: Xin Hao <xhao@linux.alibaba.com>
Signed-off-by: Shawn Wang <shawnwang@linux.alibaba.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Tested-by: Reinette Chatre <reinette.chatre@intel.com>
Cc:stable@vger.kernel.org
Link: https://lore.kernel.org/all/2fad13f49fbe89687fc40e9a5a61f23a28d1507a.1673988935.git.reinette.chatre%40intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
index 1dafbdc5ac31627e9391832fdf032685871eb637..84f23327caed4b9a5aba24b614e53400d808d5d1 100644 (file)
--- 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));
-       }
+       rdt_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:
+       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 5f7128686cfd2f851b92707afedd6e7d313dfeab..0b5c6c76f6f7b500573b64d1ffc0bf29476b3d0d 100644 (file)
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -537,5 +537,6 @@ 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 87b670d540b842d0532e609eab5c67d322dff1b0..c7f1c7cb1963b5413348d018997e067dd5726af0 100644 (file)
--- 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,