linux-kernel - [PATCH v8 4/9] x86/cpufeatures: Enumerate ENQCMD and ENQCMDS instructions

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Date:   Tue, 15 Sep 2020 09:30:08 -0700
From:   Fenghua Yu <fenghua.yu@...el.com>
To:     "Thomas Gleixner" <tglx@...utronix.de>,
        "Borislav Petkov" <bp@...en8.de>, "Ingo Molnar" <mingo@...hat.com>,
        "H Peter Anvin" <hpa@...or.com>,
        "Andy Lutomirski" <luto@...nel.org>,
        "Jean-Philippe Brucker" <jean-philippe@...aro.org>,
        "Christoph Hellwig" <hch@...radead.org>,
        "Peter Zijlstra" <peterz@...radead.org>,
        "David Woodhouse" <dwmw2@...radead.org>,
        "Lu Baolu" <baolu.lu@...ux.intel.com>,
        "Dave Hansen" <dave.hansen@...el.com>,
        "Tony Luck" <tony.luck@...el.com>,
        "Randy Dunlap" <rdunlap@...radead.org>,
        "Ashok Raj" <ashok.raj@...el.com>,
        "Jacob Jun Pan" <jacob.jun.pan@...el.com>,
        "Dave Jiang" <dave.jiang@...el.com>,
        "Sohil Mehta" <sohil.mehta@...el.com>,
        "Ravi V Shankar" <ravi.v.shankar@...el.com>
Cc:     "linux-kernel" <linux-kernel@...r.kernel.org>,
        "x86" <x86@...nel.org>, iommu@...ts.linux-foundation.org,
        Fenghua Yu <fenghua.yu@...el.com>
Subject: [PATCH v8 4/9] x86/cpufeatures: Enumerate ENQCMD and ENQCMDS instructions

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>
---
v2:
- Re-write commit message (Thomas)

 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 2901d5df4366..fea10d04d05f 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -353,6 +353,7 @@
 #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    },
 	{}
 };
 
-- 
2.19.1