linux-kernel - [RFC PATCH 20/22] x86/fpu/amx: Enable the AMX feature in 64-bit mode

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Message-Id: <20201001203913.9125-21-chang.seok.bae@intel.com>
Date:   Thu,  1 Oct 2020 13:39:11 -0700
From:   "Chang S. Bae" <chang.seok.bae@...el.com>
To:     tglx@...utronix.de, mingo@...nel.org, bp@...e.de, luto@...nel.org,
        x86@...nel.org
Cc:     len.brown@...el.com, dave.hansen@...el.com, jing2.liu@...el.com,
        ravi.v.shankar@...el.com, linux-kernel@...r.kernel.org,
        chang.seok.bae@...el.com
Subject: [RFC PATCH 20/22] x86/fpu/amx: Enable the AMX feature in 64-bit mode

In 64-bit mode, include the AMX state components in
XFEATURE_MASK_USER_SUPPORTED.

The XFD feature will be used to dynamically allocate per-task XSAVE
buffer on first use.

Signed-off-by: Chang S. Bae <chang.seok.bae@...el.com>
Reviewed-by: Len Brown <len.brown@...el.com>
Cc: x86@...nel.org
Cc: linux-kernel@...r.kernel.org
---
 arch/x86/include/asm/fpu/xstate.h | 3 ++-
 arch/x86/kernel/fpu/init.c        | 8 ++++++--
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/fpu/xstate.h b/arch/x86/include/asm/fpu/xstate.h
index aadbcf893cc0..872325768b13 100644
--- a/arch/x86/include/asm/fpu/xstate.h
+++ b/arch/x86/include/asm/fpu/xstate.h
@@ -34,7 +34,8 @@
 				      XFEATURE_MASK_Hi16_ZMM	 | \
 				      XFEATURE_MASK_PKRU | \
 				      XFEATURE_MASK_BNDREGS | \
-				      XFEATURE_MASK_BNDCSR)
+				      XFEATURE_MASK_BNDCSR | \
+				      XFEATURE_MASK_XTILE)
 
 /* All currently supported supervisor features */
 #define XFEATURE_MASK_SUPERVISOR_SUPPORTED (0)
diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c
index ee6499075a89..8e2a77bc1782 100644
--- a/arch/x86/kernel/fpu/init.c
+++ b/arch/x86/kernel/fpu/init.c
@@ -229,8 +229,12 @@ static void __init fpu__init_system_xstate_size_legacy(void)
  */
 u64 __init fpu__get_supported_xfeatures_mask(void)
 {
-	return XFEATURE_MASK_USER_SUPPORTED |
-	       XFEATURE_MASK_SUPERVISOR_SUPPORTED;
+	u64 mask = XFEATURE_MASK_USER_SUPPORTED | XFEATURE_MASK_SUPERVISOR_SUPPORTED;
+
+	if (!IS_ENABLED(CONFIG_X86_64))
+		mask &= ~(XFEATURE_MASK_XTILE);
+
+	return mask;
 }
 
 /* Legacy code to initialize eager fpu mode. */
-- 
2.17.1