x86/intel_rdt: Add diagnostics when writing the schemata file

Save helpful descriptions of what went wrong when writing a
schemata file.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Vikas Shivappa <vikas.shivappa@intel.com>
Cc: Boris Petkov <bp@suse.de>
Cc: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lkml.kernel.org/r/9d6cef757dc88639c8ab47f1e7bc1b081a84bb88.1506382469.git.tony.luck@intel.com

diff --git a/arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c b/arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c
index f6ea94f..f29b4c2 100644 (file)
--- a/arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c
+++ b/arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c
@@ -42,15 +42,22 @@ static bool bw_validate(char *buf, unsigned long *data, struct rdt_resource *r)
        /*
         * Only linear delay values is supported for current Intel SKUs.
         */
-       if (!r->membw.delay_linear)
+       if (!r->membw.delay_linear) {
+               rdt_last_cmd_puts("No support for non-linear MB domains\n");
                return false;
+       }
 
        ret = kstrtoul(buf, 10, &bw);
-       if (ret)
+       if (ret) {
+               rdt_last_cmd_printf("Non-decimal digit in MB value %s\n", buf);
                return false;
+       }
 
-       if (bw < r->membw.min_bw || bw > r->default_ctrl)
+       if (bw < r->membw.min_bw || bw > r->default_ctrl) {
+               rdt_last_cmd_printf("MB value %ld out of range [%d,%d]\n", bw,
+                                   r->membw.min_bw, r->default_ctrl);
                return false;
+       }
 
        *data = roundup(bw, (unsigned long)r->membw.bw_gran);
        return true;
@@ -60,8 +67,10 @@ int parse_bw(char *buf, struct rdt_resource *r, struct rdt_domain *d)
 {
        unsigned long data;
 
-       if (d->have_new_ctrl)
+       if (d->have_new_ctrl) {
+               rdt_last_cmd_printf("duplicate domain %d\n", d->id);
                return -EINVAL;
+       }
 
        if (!bw_validate(buf, &data, r))
                return -EINVAL;
@@ -84,20 +93,29 @@ static bool cbm_validate(char *buf, unsigned long *data, struct rdt_resource *r)
        int ret;
 
        ret = kstrtoul(buf, 16, &val);
-       if (ret)
+       if (ret) {
+               rdt_last_cmd_printf("non-hex character in mask %s\n", buf);
                return false;
+       }
 
-       if (val == 0 || val > r->default_ctrl)
+       if (val == 0 || val > r->default_ctrl) {
+               rdt_last_cmd_puts("mask out of range\n");
                return false;
+       }
 
        first_bit = find_first_bit(&val, cbm_len);
        zero_bit = find_next_zero_bit(&val, cbm_len, first_bit);
 
-       if (find_next_bit(&val, cbm_len, zero_bit) < cbm_len)
+       if (find_next_bit(&val, cbm_len, zero_bit) < cbm_len) {
+               rdt_last_cmd_printf("mask %lx has non-consecutive 1-bits\n", val);
                return false;
+       }
 
-       if ((zero_bit - first_bit) < r->cache.min_cbm_bits)
+       if ((zero_bit - first_bit) < r->cache.min_cbm_bits) {
+               rdt_last_cmd_printf("Need at least %d bits in mask\n",
+                                   r->cache.min_cbm_bits);
                return false;
+       }
 
        *data = val;
        return true;
@@ -111,8 +129,10 @@ int parse_cbm(char *buf, struct rdt_resource *r, struct rdt_domain *d)
 {
        unsigned long data;
 
-       if (d->have_new_ctrl)
+       if (d->have_new_ctrl) {
+               rdt_last_cmd_printf("duplicate domain %d\n", d->id);
                return -EINVAL;
+       }
 
        if(!cbm_validate(buf, &data, r))
                return -EINVAL;
@@ -139,8 +159,10 @@ next:
                return 0;
        dom = strsep(&line, ";");
        id = strsep(&dom, "=");
-       if (!dom || kstrtoul(id, 10, &dom_id))
+       if (!dom || kstrtoul(id, 10, &dom_id)) {
+               rdt_last_cmd_puts("Missing '=' or non-numeric domain\n");
                return -EINVAL;
+       }
        dom = strim(dom);
        list_for_each_entry(d, &r->domains, list) {
                if (d->id == dom_id) {
@@ -196,6 +218,7 @@ static int rdtgroup_parse_resource(char *resname, char *tok, int closid)
                if (!strcmp(resname, r->name) && closid < r->num_closid)
                        return parse_line(tok, r);
        }
+       rdt_last_cmd_printf("unknown/unsupported resource name '%s'\n", resname);
        return -EINVAL;
 }
 
@@ -209,8 +232,10 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of,
        int closid, ret = 0;
 
        /* Valid input requires a trailing newline */
-       if (nbytes == 0 || buf[nbytes - 1] != '\n')
+       if (nbytes == 0 || buf[nbytes - 1] != '\n') {
+               seq_buf_puts(&last_cmd_status, "no trailing newline\n");
                return -EINVAL;
+       }
        buf[nbytes - 1] = '\0';
 
        rdtgrp = rdtgroup_kn_lock_live(of->kn);
@@ -218,6 +243,7 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of,
                rdtgroup_kn_unlock(of->kn);
                return -ENOENT;
        }
+       rdt_last_cmd_clear();
 
        closid = rdtgrp->closid;
 
@@ -229,6 +255,7 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of,
        while ((tok = strsep(&buf, "\n")) != NULL) {
                resname = strim(strsep(&tok, ":"));
                if (!tok) {
+                       rdt_last_cmd_puts("Missing ':'\n");
                        ret = -EINVAL;
                        goto out;
                }