[PATCH v5 1/8] x86/cpufeatures: Add support for L3 Smart Data Cache Injection Allocation Enforcement

[Babu Moger <babu.moger@amd.com>]

Smart Data Cache Injection (SDCI) is a mechanism that enables direct
insertion of data from I/O devices into the L3 cache. By directly caching
data from I/O devices rather than first storing the I/O data in DRAM,
SDCI reduces demands on DRAM bandwidth and reduces latency to the processor
consuming the I/O data.

The SDCIAE (SDCI Allocation Enforcement) PQE feature allows system software
to control the portion of the L3 cache used for SDCI.

When enabled, SDCIAE forces all SDCI lines to be placed into the L3 cache
partitions identified by the highest-supported L3_MASK_n register, where n
is the maximum supported CLOSID.

Add CPUID feature bit that can be used to configure SDCIAE.

The feature details are documented in APM listed below [1].
[1] AMD64 Architecture Programmer's Manual Volume 2: System Programming
Publication # 24593 Revision 3.41 section 19.4.7 L3 Smart Data Cache
Injection Allocation Enforcement (SDCIAE)

Link: https://bugzilla.kernel.org/show_bug.cgi?id=206537
Signed-off-by: Babu Moger <babu.moger@amd.com>
---
v5: No changes.

v4: Resolved a minor conflict in cpufeatures.h.

v3: No changes.

v2: Added dependancy on X86_FEATURE_CAT_L3
    Removed the "" in CPU feature definition.
    Minor text changes.
---
 arch/x86/include/asm/cpufeatures.h | 1 +
 arch/x86/kernel/cpu/cpuid-deps.c   | 1 +
 arch/x86/kernel/cpu/scattered.c    | 1 +
 3 files changed, 3 insertions(+)

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 6c2c152d8a67..8dfbea91bef6 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -481,6 +481,7 @@
 #define X86_FEATURE_AMD_HETEROGENEOUS_CORES (21*32 + 6) /* Heterogeneous Core Topology */
 #define X86_FEATURE_AMD_WORKLOAD_CLASS	(21*32 + 7) /* Workload Classification */
 #define X86_FEATURE_PREFER_YMM		(21*32 + 8) /* Avoid ZMM registers due to downclocking */
+#define X86_FEATURE_SDCIAE		(21*32 + 9) /* L3 Smart Data Cache Injection Allocation Enforcement */
 
 /*
  * BUG word(s)
diff --git a/arch/x86/kernel/cpu/cpuid-deps.c b/arch/x86/kernel/cpu/cpuid-deps.c
index a2fbea0be535..2687ae01a471 100644
--- a/arch/x86/kernel/cpu/cpuid-deps.c
+++ b/arch/x86/kernel/cpu/cpuid-deps.c
@@ -71,6 +71,7 @@ static const struct cpuid_dep cpuid_deps[] = {
 	{ X86_FEATURE_CQM_MBM_LOCAL,		X86_FEATURE_CQM_LLC   },
 	{ X86_FEATURE_BMEC,			X86_FEATURE_CQM_MBM_TOTAL   },
 	{ X86_FEATURE_BMEC,			X86_FEATURE_CQM_MBM_LOCAL   },
+	{ X86_FEATURE_SDCIAE,			X86_FEATURE_CAT_L3    },
 	{ X86_FEATURE_AVX512_BF16,		X86_FEATURE_AVX512VL  },
 	{ X86_FEATURE_AVX512_FP16,		X86_FEATURE_AVX512BW  },
 	{ X86_FEATURE_ENQCMD,			X86_FEATURE_XSAVES    },
diff --git a/arch/x86/kernel/cpu/scattered.c b/arch/x86/kernel/cpu/scattered.c
index 16f3ca30626a..d18a7ce16388 100644
--- a/arch/x86/kernel/cpu/scattered.c
+++ b/arch/x86/kernel/cpu/scattered.c
@@ -49,6 +49,7 @@ static const struct cpuid_bit cpuid_bits[] = {
 	{ X86_FEATURE_MBA,			CPUID_EBX,  6, 0x80000008, 0 },
 	{ X86_FEATURE_SMBA,			CPUID_EBX,  2, 0x80000020, 0 },
 	{ X86_FEATURE_BMEC,			CPUID_EBX,  3, 0x80000020, 0 },
+	{ X86_FEATURE_SDCIAE,			CPUID_EBX,  6, 0x80000020, 0 },
 	{ X86_FEATURE_AMD_WORKLOAD_CLASS,	CPUID_EAX, 22, 0x80000021, 0 },
 	{ X86_FEATURE_PERFMON_V2,		CPUID_EAX,  0, 0x80000022, 0 },
 	{ X86_FEATURE_AMD_LBR_V2,		CPUID_EAX,  1, 0x80000022, 0 },
-- 
2.34.1