[PATCH v4 07/18] x86/intel_rdt: Add Haswell feature discovery

[Fenghua Yu]

From: Fenghua Yu <fenghua.yu@xxxxxxxxx>

Some Haswell generation CPUs support RDT, but they don't enumerate this
using CPUID.  Use rdmsr_safe() and wrmsr_safe() to probe the MSRs on
cpu model 63 (INTEL_FAM6_HASWELL_X)

Signed-off-by: Fenghua Yu <fenghua.yu@xxxxxxxxx>
Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>
---
 arch/x86/events/intel/cqm.c             |  2 +-
 arch/x86/include/asm/intel_rdt.h        |  6 +++++
 arch/x86/include/asm/intel_rdt_common.h |  6 +++++
 arch/x86/kernel/cpu/intel_rdt.c         | 41 +++++++++++++++++++++++++++++++++
 4 files changed, 54 insertions(+), 1 deletion(-)
 create mode 100644 arch/x86/include/asm/intel_rdt.h
 create mode 100644 arch/x86/include/asm/intel_rdt_common.h

diff --git a/arch/x86/events/intel/cqm.c b/arch/x86/events/intel/cqm.c
index 8f82b02..df86874 100644
--- a/arch/x86/events/intel/cqm.c
+++ b/arch/x86/events/intel/cqm.c
@@ -7,9 +7,9 @@
 #include <linux/perf_event.h>
 #include <linux/slab.h>
 #include <asm/cpu_device_id.h>
+#include <asm/intel_rdt_common.h>
 #include "../perf_event.h"
 
-#define MSR_IA32_PQR_ASSOC	0x0c8f
 #define MSR_IA32_QM_CTR		0x0c8e
 #define MSR_IA32_QM_EVTSEL	0x0c8d
 
diff --git a/arch/x86/include/asm/intel_rdt.h b/arch/x86/include/asm/intel_rdt.h
new file mode 100644
index 0000000..3aca86d
--- /dev/null
+++ b/arch/x86/include/asm/intel_rdt.h
@@ -0,0 +1,6 @@
+#ifndef _ASM_X86_INTEL_RDT_H
+#define _ASM_X86_INTEL_RDT_H
+
+#define IA32_L3_CBM_BASE	0xc90
+
+#endif /* _ASM_X86_INTEL_RDT_H */
diff --git a/arch/x86/include/asm/intel_rdt_common.h b/arch/x86/include/asm/intel_rdt_common.h
new file mode 100644
index 0000000..e6e15cf
--- /dev/null
+++ b/arch/x86/include/asm/intel_rdt_common.h
@@ -0,0 +1,6 @@
+#ifndef _ASM_X86_INTEL_RDT_COMMON_H
+#define _ASM_X86_INTEL_RDT_COMMON_H
+
+#define MSR_IA32_PQR_ASSOC	0x0c8f
+
+#endif /* _ASM_X86_INTEL_RDT_COMMON_H */
diff --git a/arch/x86/kernel/cpu/intel_rdt.c b/arch/x86/kernel/cpu/intel_rdt.c
index 7d7aebe..9d55942 100644
--- a/arch/x86/kernel/cpu/intel_rdt.c
+++ b/arch/x86/kernel/cpu/intel_rdt.c
@@ -27,10 +27,51 @@
 #include <linux/slab.h>
 #include <linux/err.h>
 
+#include <asm/intel_rdt_common.h>
+#include <asm/intel-family.h>
+#include <asm/intel_rdt.h>
+
+/*
+ * cache_alloc_hsw_probe() - Have to probe for Intel haswell server CPUs
+ * as they do not have CPUID enumeration support for Cache allocation.
+ * The check for Vendor/Family/Model is not enough to guarantee that
+ * the MSRs won't #GP fault because only the following SKUs support
+ * CAT:
+ *	Intel(R) Xeon(R)  CPU E5-2658  v3  @  2.20GHz
+ *	Intel(R) Xeon(R)  CPU E5-2648L v3  @  1.80GHz
+ *	Intel(R) Xeon(R)  CPU E5-2628L v3  @  2.00GHz
+ *	Intel(R) Xeon(R)  CPU E5-2618L v3  @  2.30GHz
+ *	Intel(R) Xeon(R)  CPU E5-2608L v3  @  2.00GHz
+ *	Intel(R) Xeon(R)  CPU E5-2658A v3  @  2.20GHz
+ *
+ * Probe by trying to write the first of the L3 cach mask registers
+ * and checking that the bits stick. Max CLOSids is always 4 and max cbm length
+ * is always 20 on hsw server parts. The minimum cache bitmask length
+ * allowed for HSW server is always 2 bits. Hardcode all of them.
+ */
+static inline bool cache_alloc_hsw_probe(void)
+{
+	u32 l, h;
+	u32 max_cbm = BIT_MASK(20) - 1;
+
+	if (wrmsr_safe(IA32_L3_CBM_BASE, max_cbm, 0))
+		return false;
+	rdmsr(IA32_L3_CBM_BASE, l, h);
+	if (l != max_cbm)
+		return false;
+
+	return true;
+}
+
 static inline bool get_rdt_resources(void)
 {
 	bool ret = false;
 
+	if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
+	    boot_cpu_data.x86 == 6 &&
+	    boot_cpu_data.x86_model == INTEL_FAM6_HASWELL_X)
+		return cache_alloc_hsw_probe();
+
 	if (!boot_cpu_has(X86_FEATURE_RDT_A))
 		return false;
 	if (boot_cpu_has(X86_FEATURE_CAT_L3))
-- 
2.5.0