x86/intel_rdt: Implement "update" mode when writing schemata file

The schemata file can have multiple lines and it is cumbersome to update
all lines.

Remove code that requires that the user provides values for every resource
(in the right order).  If the user provides values for just a few
resources, update them and leave the rest unchanged.

Side benefit: we now check which values were updated and only send IPIs to
cpus that actually have updates.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Vikas Shivappa <vikas.shivappa@linux.intel.com>
Tested-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Cc: ravi.v.shankar@intel.com
Cc: fenghua.yu@intel.com
Cc: peterz@infradead.org
Cc: vikas.shivappa@intel.com
Cc: h.peter.anvin@intel.com
Link: http://lkml.kernel.org/r/1491255857-17213-3-git-send-email-vikas.shivappa@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/Documentation/x86/intel_rdt_ui.txt b/Documentation/x86/intel_rdt_ui.txt
index 51cf6fa5591f9e99d95e73212e19372821ae4d7f..3ea1984604697fe594cb9ea843b4603a070e86b9 100644 (file)
--- a/Documentation/x86/intel_rdt_ui.txt
+++ b/Documentation/x86/intel_rdt_ui.txt
@@ -129,6 +129,20 @@ schemata format is always:
 
        L2:<cache_id0>=<cbm>;<cache_id1>=<cbm>;...
 
+Reading/writing the schemata file
+---------------------------------
+Reading the schemata file will show the state of all resources
+on all domains. When writing you only need to specify those values
+which you wish to change.  E.g.
+
+# cat schemata
+L3DATA:0=fffff;1=fffff;2=fffff;3=fffff
+L3CODE:0=fffff;1=fffff;2=fffff;3=fffff
+# echo "L3DATA:2=3c0;" > schemata
+# cat schemata
+L3DATA:0=fffff;1=fffff;2=3c0;3=fffff
+L3CODE:0=fffff;1=fffff;2=fffff;3=fffff
+
 Example 1
 ---------
 On a two socket machine (one L3 cache per socket) with just four bits

diff --git a/arch/x86/include/asm/intel_rdt.h b/arch/x86/include/asm/intel_rdt.h
index 0d64397cee58e05344a0d3a2d14038e6224381b7..d7705270c4010504d900ffb2723bb8de71bb6309 100644 (file)
--- a/arch/x86/include/asm/intel_rdt.h
+++ b/arch/x86/include/asm/intel_rdt.h
@@ -76,10 +76,7 @@ struct rftype {
  * @min_cbm_bits:              Minimum number of consecutive bits to be set
  *                             in a cache bit mask
  * @domains:                   All domains for this resource
- * @num_domains:               Number of domains active
  * @msr_base:                  Base MSR address for CBMs
- * @tmp_cbms:                  Scratch space when updating schemata
- * @num_tmp_cbms:              Number of CBMs in tmp_cbms
  * @cache_level:               Which cache level defines scope of this domain
  * @cbm_idx_multi:             Multiplier of CBM index
  * @cbm_idx_offset:            Offset of CBM index. CBM index is computed by:
@@ -94,10 +91,7 @@ struct rdt_resource {
        int                     min_cbm_bits;
        u32                     max_cbm;
        struct list_head        domains;
-       int                     num_domains;
        int                     msr_base;
-       u32                     *tmp_cbms;
-       int                     num_tmp_cbms;
        int                     cache_level;
        int                     cbm_idx_multi;
        int                     cbm_idx_offset;
@@ -109,12 +103,16 @@ struct rdt_resource {
  * @id:                unique id for this instance
  * @cpu_mask:  which cpus share this resource
  * @cbm:       array of cache bit masks (indexed by CLOSID)
+ * @new_cbm:   new cbm value to be loaded
+ * @have_new_cbm: did user provide new_cbm for this domain
  */
 struct rdt_domain {
        struct list_head        list;
        int                     id;
        struct cpumask          cpu_mask;
        u32                     *cbm;
+       u32                     new_cbm;
+       bool                    have_new_cbm;
 };
 
 /**

diff --git a/arch/x86/kernel/cpu/intel_rdt.c b/arch/x86/kernel/cpu/intel_rdt.c
index 5a533fefefa0829b419c21cebcb10a89161dd3ec..329b8876b984b0deeee11a0e48609e761487bb6d 100644 (file)
--- a/arch/x86/kernel/cpu/intel_rdt.c
+++ b/arch/x86/kernel/cpu/intel_rdt.c
@@ -309,7 +309,6 @@ static void domain_add_cpu(int cpu, struct rdt_resource *r)
 
        cpumask_set_cpu(cpu, &d->cpu_mask);
        list_add_tail(&d->list, add_pos);
-       r->num_domains++;
 }
 
 static void domain_remove_cpu(int cpu, struct rdt_resource *r)
@@ -325,7 +324,6 @@ static void domain_remove_cpu(int cpu, struct rdt_resource *r)
 
        cpumask_clear_cpu(cpu, &d->cpu_mask);
        if (cpumask_empty(&d->cpu_mask)) {
-               r->num_domains--;
                kfree(d->cbm);
                list_del(&d->list);
                kfree(d);

diff --git a/arch/x86/kernel/cpu/intel_rdt_schemata.c b/arch/x86/kernel/cpu/intel_rdt_schemata.c
index f369cb8db0d5b4332125745dd5a587148f109597..52e83eabd9b721e475045e2402253a69a2e40177 100644 (file)
--- a/arch/x86/kernel/cpu/intel_rdt_schemata.c
+++ b/arch/x86/kernel/cpu/intel_rdt_schemata.c
@@ -56,17 +56,21 @@ static bool cbm_validate(unsigned long var, struct rdt_resource *r)
  * Read one cache bit mask (hex). Check that it is valid for the current
  * resource type.
  */
-static int parse_cbm(char *buf, struct rdt_resource *r)
+static int parse_cbm(char *buf, struct rdt_resource *r, struct rdt_domain *d)
 {
        unsigned long data;
        int ret;
 
+       if (d->have_new_cbm)
+               return -EINVAL;
+
        ret = kstrtoul(buf, 16, &data);
        if (ret)
                return ret;
        if (!cbm_validate(data, r))
                return -EINVAL;
-       r->tmp_cbms[r->num_tmp_cbms++] = data;
+       d->new_cbm = data;
+       d->have_new_cbm = true;
 
        return 0;
 }
@@ -74,8 +78,8 @@ static int parse_cbm(char *buf, struct rdt_resource *r)
 /*
  * For each domain in this resource we expect to find a series of:
  *     id=mask
- * separated by ";". The "id" is in decimal, and must appear in the
- * right order.
+ * separated by ";". The "id" is in decimal, and must match one of
+ * the "id"s for this resource.
  */
 static int parse_line(char *line, struct rdt_resource *r)
 {
@@ -83,21 +87,21 @@ static int parse_line(char *line, struct rdt_resource *r)
        struct rdt_domain *d;
        unsigned long dom_id;
 
+next:
+       if (!line || line[0] == '\0')
+               return 0;
+       dom = strsep(&line, ";");
+       id = strsep(&dom, "=");
+       if (!dom || kstrtoul(id, 10, &dom_id))
+               return -EINVAL;
        list_for_each_entry(d, &r->domains, list) {
-               dom = strsep(&line, ";");
-               if (!dom)
-                       return -EINVAL;
-               id = strsep(&dom, "=");
-               if (kstrtoul(id, 10, &dom_id) || dom_id != d->id)
-                       return -EINVAL;
-               if (parse_cbm(dom, r))
-                       return -EINVAL;
+               if (d->id == dom_id) {
+                       if (parse_cbm(dom, r, d))
+                               return -EINVAL;
+                       goto next;
+               }
        }
-
-       /* Any garbage at the end of the line? */
-       if (line && line[0])
-               return -EINVAL;
-       return 0;
+       return -EINVAL;
 }
 
 static int update_domains(struct rdt_resource *r, int closid)
@@ -105,7 +109,7 @@ static int update_domains(struct rdt_resource *r, int closid)
        struct msr_param msr_param;
        cpumask_var_t cpu_mask;
        struct rdt_domain *d;
-       int cpu, idx = 0;
+       int cpu;
 
        if (!zalloc_cpumask_var(&cpu_mask, GFP_KERNEL))
                return -ENOMEM;
@@ -115,9 +119,13 @@ static int update_domains(struct rdt_resource *r, int closid)
        msr_param.res = r;
 
        list_for_each_entry(d, &r->domains, list) {
-               cpumask_set_cpu(cpumask_any(&d->cpu_mask), cpu_mask);
-               d->cbm[msr_param.low] = r->tmp_cbms[idx++];
+               if (d->have_new_cbm && d->new_cbm != d->cbm[closid]) {
+                       cpumask_set_cpu(cpumask_any(&d->cpu_mask), cpu_mask);
+                       d->cbm[closid] = d->new_cbm;
+               }
        }
+       if (cpumask_empty(cpu_mask))
+               goto done;
        cpu = get_cpu();
        /* Update CBM on this cpu if it's in cpu_mask. */
        if (cpumask_test_cpu(cpu, cpu_mask))
@@ -126,6 +134,7 @@ static int update_domains(struct rdt_resource *r, int closid)
        smp_call_function_many(cpu_mask, rdt_cbm_update, &msr_param, 1);
        put_cpu();
 
+done:
        free_cpumask_var(cpu_mask);
 
        return 0;
@@ -135,10 +144,10 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of,
                                char *buf, size_t nbytes, loff_t off)
 {
        struct rdtgroup *rdtgrp;
+       struct rdt_domain *dom;
        struct rdt_resource *r;
        char *tok, *resname;
        int closid, ret = 0;
-       u32 *l3_cbms = NULL;
 
        /* Valid input requires a trailing newline */
        if (nbytes == 0 || buf[nbytes - 1] != '\n')
@@ -153,16 +162,9 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of,
 
        closid = rdtgrp->closid;
 
-       /* get scratch space to save all the masks while we validate input */
-       for_each_enabled_rdt_resource(r) {
-               r->tmp_cbms = kcalloc(r->num_domains, sizeof(*l3_cbms),
-                                     GFP_KERNEL);
-               if (!r->tmp_cbms) {
-                       ret = -ENOMEM;
-                       goto out;
-               }
-               r->num_tmp_cbms = 0;
-       }
+       for_each_enabled_rdt_resource(r)
+               list_for_each_entry(dom, &r->domains, list)
+                       dom->have_new_cbm = false;
 
        while ((tok = strsep(&buf, "\n")) != NULL) {
                resname = strsep(&tok, ":");
@@ -185,14 +187,6 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of,
                }
        }
 
-       /* Did the parser find all the masks we need? */
-       for_each_enabled_rdt_resource(r) {
-               if (r->num_tmp_cbms != r->num_domains) {
-                       ret = -EINVAL;
-                       goto out;
-               }
-       }
-
        for_each_enabled_rdt_resource(r) {
                ret = update_domains(r, closid);
                if (ret)
@@ -201,10 +195,6 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of,
 
 out:
        rdtgroup_kn_unlock(of->kn);
-       for_each_enabled_rdt_resource(r) {
-               kfree(r->tmp_cbms);
-               r->tmp_cbms = NULL;
-       }
        return ret ?: nbytes;
 }