linux-kernel - [PATCH v3 1/6] x86/cpufeatures: Enumerate ENQCMD and ENQCMDS instructions

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Message-ID: <159405969206.19216.9552068036045362031.stgit@djiang5-desk3.ch.intel.com>
Date:   Mon, 06 Jul 2020 11:21:32 -0700
From:   Dave Jiang <dave.jiang@...el.com>
To:     vkoul@...nel.org, tglx@...utronix.de, mingo@...hat.com,
        bp@...en8.de
Cc:     Fenghua Yu <fenghua.yu@...el.com>, Tony Luck <tony.luck@...el.com>,
        dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org,
        x86@...nel.org, dan.j.williams@...el.com, ashok.raj@...el.com,
        fenghua.yu@...el.com, tony.luck@...el.com, jing.lin@...el.com
Subject: [PATCH v3 1/6] x86/cpufeatures: Enumerate ENQCMD and ENQCMDS
 instructions

From: Fenghua Yu <fenghua.yu@...el.com>

Work submission instruction comes in two flavors. ENQCMD can be called
both in ring 3 and ring 0 and always uses the contents of PASID MSR when
shipping the command to the device. ENQCMDS allows a kernel driver to
submit commands on behalf of a user process. The driver supplies the
PASID value in ENQCMDS. There isn't any usage of ENQCMD in the kernel
as of now.

The CPU feature flag is shown as "enqcmd" in /proc/cpuinfo.

Signed-off-by: Fenghua Yu <fenghua.yu@...el.com>
Reviewed-by: Tony Luck <tony.luck@...el.com>

This patch is here only for compilation reasons. Drop when Fenghua's patch
series gets accepted upstream.
---
 arch/x86/include/asm/cpufeatures.h |    1 +
 arch/x86/kernel/cpu/cpuid-deps.c   |    1 +
 2 files changed, 2 insertions(+)

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 02dabc9e77b0..4469618c410f 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -351,6 +351,7 @@
 #define X86_FEATURE_CLDEMOTE		(16*32+25) /* CLDEMOTE instruction */
 #define X86_FEATURE_MOVDIRI		(16*32+27) /* MOVDIRI instruction */
 #define X86_FEATURE_MOVDIR64B		(16*32+28) /* MOVDIR64B instruction */
+#define X86_FEATURE_ENQCMD		(16*32+29) /* ENQCMD and ENQCMDS instructions */
 
 /* AMD-defined CPU features, CPUID level 0x80000007 (EBX), word 17 */
 #define X86_FEATURE_OVERFLOW_RECOV	(17*32+ 0) /* MCA overflow recovery support */
diff --git a/arch/x86/kernel/cpu/cpuid-deps.c b/arch/x86/kernel/cpu/cpuid-deps.c
index 3cbe24ca80ab..3a02707c1f4d 100644
--- a/arch/x86/kernel/cpu/cpuid-deps.c
+++ b/arch/x86/kernel/cpu/cpuid-deps.c
@@ -69,6 +69,7 @@ static const struct cpuid_dep cpuid_deps[] = {
 	{ X86_FEATURE_CQM_MBM_TOTAL,		X86_FEATURE_CQM_LLC   },
 	{ X86_FEATURE_CQM_MBM_LOCAL,		X86_FEATURE_CQM_LLC   },
 	{ X86_FEATURE_AVX512_BF16,		X86_FEATURE_AVX512VL  },
+	{ X86_FEATURE_ENQCMD,			X86_FEATURE_XSAVES    },
 	{}
 };