Merge branch 'x86-cache-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 cache resource updates from Thomas Gleixner:
 "This update provides updates to RDT:

  - A diagnostic framework for the Resource Director Technology (RDT)
    user interface (sysfs). The failure modes of the user interface are
    hard to diagnose from the error codes. An extra last command status
    file provides now sensible textual information about the failure so
    its simpler to use.

  - A few minor cleanups and updates in the RDT code"

* 'x86-cache-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/intel_rdt: Fix a silent failure when writing zero value schemata
  x86/intel_rdt: Fix potential deadlock during resctrl mount
  x86/intel_rdt: Fix potential deadlock during resctrl unmount
  x86/intel_rdt: Initialize bitmask of shareable resource if CDP enabled
  x86/intel_rdt: Remove redundant assignment
  x86/intel_rdt/cqm: Make integer rmid_limbo_count static
  x86/intel_rdt: Add documentation for "info/last_cmd_status"
  x86/intel_rdt: Add diagnostics when making directories
  x86/intel_rdt: Add diagnostics when writing the cpus file
  x86/intel_rdt: Add diagnostics when writing the tasks file
  x86/intel_rdt: Add diagnostics when writing the schemata file
  x86/intel_rdt: Add framework for better RDT UI diagnostics

1 files changed, 40 insertions, 10 deletions

diff --git a/arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c b/arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c
index f6ea94f8954a..23e1d5c249c6 100644
--- 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;
 }
 
@@ -218,6 +241,7 @@ 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 +253,12 @@ 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;
+		}
+		if (tok[0] == '\0') {
+			rdt_last_cmd_printf("Missing '%s' value\n", resname);
 			ret = -EINVAL;
 			goto out;
 		}