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Subject[PATCH 2/3] x86/intel_rdt: Add command line options for resource director technology
Date
From: Tony Luck <tony.luck@intel.com>

Command line options allow us to ignore features that we don't want.
Also we can re-enable options that have been disabled on a platform
(so long as the underlying h/w actually supports the option).

Signed-off-by: Tony Luck <tony.luck@intel.com>
---
Documentation/admin-guide/kernel-parameters.rst | 1 +
Documentation/admin-guide/kernel-parameters.txt | 6 ++
arch/x86/kernel/cpu/intel_rdt.c | 94 ++++++++++++++++++++++---
3 files changed, 93 insertions(+), 8 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.rst b/Documentation/admin-guide/kernel-parameters.rst
index d76ab3907e2b..b2598cc9834c 100644
--- a/Documentation/admin-guide/kernel-parameters.rst
+++ b/Documentation/admin-guide/kernel-parameters.rst
@@ -138,6 +138,7 @@ parameter is applicable::
PPT Parallel port support is enabled.
PS2 Appropriate PS/2 support is enabled.
RAM RAM disk support is enabled.
+ RDT Intel Resource Director Technology.
S390 S390 architecture is enabled.
SCSI Appropriate SCSI support is enabled.
A lot of drivers have their options described inside
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index d9c171ce4190..ef52ae4ed6e8 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3598,6 +3598,12 @@
Run specified binary instead of /init from the ramdisk,
used for early userspace startup. See initrd.

+ rdt= [HW,X86,RDT]
+ Turn on/off individual RDT features. List is:
+ cmt, mbmtotal, mbmlocal, l3cat, l3cdp, l2cat, mba.
+ E.g. to turn on cmt and turn off mba use:
+ rdt=cmt,!mba
+
reboot= [KNL]
Format (x86 or x86_64):
[w[arm] | c[old] | h[ard] | s[oft] | g[pio]] \
diff --git a/arch/x86/kernel/cpu/intel_rdt.c b/arch/x86/kernel/cpu/intel_rdt.c
index 25514cd454b3..65222d8fd5ec 100644
--- a/arch/x86/kernel/cpu/intel_rdt.c
+++ b/arch/x86/kernel/cpu/intel_rdt.c
@@ -637,6 +637,83 @@ static __init void rdt_init_padding(void)
}
}

+enum {
+ RDT_FLAG_CMT,
+ RDT_FLAG_MBM_TOTAL,
+ RDT_FLAG_MBM_LOCAL,
+ RDT_FLAG_L3_CAT,
+ RDT_FLAG_L3_CDP,
+ RDT_FLAG_L2_CAT,
+ RDT_FLAG_MBA,
+};
+
+#define RDT_OPT(idx, n, f) \
+[idx] = { \
+ .name = n, \
+ .flag = f \
+}
+
+static struct rdt_options {
+ char *name;
+ int flag;
+ bool force_off, force_on;
+} rdt_options[] = {
+ RDT_OPT(RDT_FLAG_CMT, "cmt", X86_FEATURE_CQM_OCCUP_LLC),
+ RDT_OPT(RDT_FLAG_MBM_TOTAL, "mbmtotal", X86_FEATURE_CQM_MBM_TOTAL),
+ RDT_OPT(RDT_FLAG_MBM_LOCAL, "mbmlocal", X86_FEATURE_CQM_MBM_LOCAL),
+ RDT_OPT(RDT_FLAG_L3_CAT, "l3cat", X86_FEATURE_CAT_L3),
+ RDT_OPT(RDT_FLAG_L3_CDP, "l3cdp", X86_FEATURE_CDP_L3),
+ RDT_OPT(RDT_FLAG_L2_CAT, "l2cat", X86_FEATURE_CAT_L2),
+ RDT_OPT(RDT_FLAG_MBA, "mba", X86_FEATURE_MBA),
+};
+#define NUM_RDT_OPTIONS ARRAY_SIZE(rdt_options)
+
+static int __init set_rdt_options(char *str)
+{
+ struct rdt_options *o;
+ char *tok;
+ bool force_off;
+
+ if (*str == '=')
+ str++;
+ while ((tok = strsep(&str, ",")) != NULL) {
+ force_off = *tok == '!';
+ if (force_off)
+ tok++;
+ for (o = rdt_options; o < &rdt_options[NUM_RDT_OPTIONS]; o++) {
+ if (strcmp(tok, o->name) == 0) {
+ if (force_off)
+ o->force_off = true;
+ else
+ o->force_on = true;
+ break;
+ }
+ }
+ }
+ return 1;
+}
+__setup("rdt", set_rdt_options);
+
+static int rdt_cpu_has(int flag)
+{
+ int ret = boot_cpu_has(flag);
+ struct rdt_options *o;
+
+ if (!ret)
+ return ret;
+
+ for (o = rdt_options; o < &rdt_options[NUM_RDT_OPTIONS]; o++) {
+ if (flag == o->flag) {
+ if (o->force_off)
+ ret = 0;
+ if (o->force_on)
+ ret = 1;
+ break;
+ }
+ }
+ return ret;
+}
+
static __init bool get_rdt_alloc_resources(void)
{
bool ret = false;
@@ -647,21 +724,21 @@ static __init bool get_rdt_alloc_resources(void)
if (!boot_cpu_has(X86_FEATURE_RDT_A))
return false;

- if (boot_cpu_has(X86_FEATURE_CAT_L3)) {
+ if (rdt_cpu_has(X86_FEATURE_CAT_L3)) {
rdt_get_cache_alloc_cfg(1, &rdt_resources_all[RDT_RESOURCE_L3]);
- if (boot_cpu_has(X86_FEATURE_CDP_L3)) {
+ if (rdt_cpu_has(X86_FEATURE_CDP_L3)) {
rdt_get_cdp_l3_config(RDT_RESOURCE_L3DATA);
rdt_get_cdp_l3_config(RDT_RESOURCE_L3CODE);
}
ret = true;
}
- if (boot_cpu_has(X86_FEATURE_CAT_L2)) {
+ if (rdt_cpu_has(X86_FEATURE_CAT_L2)) {
/* CPUID 0x10.2 fields are same format at 0x10.1 */
rdt_get_cache_alloc_cfg(2, &rdt_resources_all[RDT_RESOURCE_L2]);
ret = true;
}

- if (boot_cpu_has(X86_FEATURE_MBA)) {
+ if (rdt_cpu_has(X86_FEATURE_MBA)) {
if (rdt_get_mem_config(&rdt_resources_all[RDT_RESOURCE_MBA]))
ret = true;
}
@@ -670,11 +747,11 @@ static __init bool get_rdt_alloc_resources(void)

static __init bool get_rdt_mon_resources(void)
{
- if (boot_cpu_has(X86_FEATURE_CQM_OCCUP_LLC))
+ if (rdt_cpu_has(X86_FEATURE_CQM_OCCUP_LLC))
rdt_mon_features |= (1 << QOS_L3_OCCUP_EVENT_ID);
- if (boot_cpu_has(X86_FEATURE_CQM_MBM_TOTAL))
+ if (rdt_cpu_has(X86_FEATURE_CQM_MBM_TOTAL))
rdt_mon_features |= (1 << QOS_L3_MBM_TOTAL_EVENT_ID);
- if (boot_cpu_has(X86_FEATURE_CQM_MBM_LOCAL))
+ if (rdt_cpu_has(X86_FEATURE_CQM_MBM_LOCAL))
rdt_mon_features |= (1 << QOS_L3_MBM_LOCAL_EVENT_ID);

if (!rdt_mon_features)
@@ -687,7 +764,8 @@ static __init void rdt_quirks(void)
{
switch (boot_cpu_data.x86_model) {
case INTEL_FAM6_HASWELL_X:
- cache_alloc_hsw_probe();
+ if (!rdt_options[RDT_FLAG_L3_CAT].force_off)
+ cache_alloc_hsw_probe();
break;
}
}
--
2.11.0
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