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[PATCH 2/3] x86/intel_rdt: Add command line options for resource director technology

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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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[PATCH 0/3] Provide mechanism to disable select RDT features & use for Skylake "Luck, Tony" <tony.luck@intel.com> - 2017-08-24 18:30 +0200
  [PATCH 2/3] x86/intel_rdt: Add command line options for resource director technology "Luck, Tony" <tony.luck@intel.com> - 2017-08-24 18:30 +0200
  [PATCH 3/3] x86/intel_rdt: Turn off most RDT features on Skylake "Luck, Tony" <tony.luck@intel.com> - 2017-08-24 18:40 +0200
  [PATCH 1/3] x86/intel_rdt: Move special case code for Haswell to a quirk function "Luck, Tony" <tony.luck@intel.com> - 2017-08-24 18:40 +0200

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