[PATCH v4 19/22] x86/fpu/amx: Enable the AMX feature in 64-bit mode

From: Chang S. Bae
Date: Sun Feb 21 2021 - 14:06:28 EST


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

The XFD feature will be used to dynamically expand the xstate per-task
buffer on the first use.

Signed-off-by: Chang S. Bae <chang.seok.bae@xxxxxxxxx>
Reviewed-by: Len Brown <len.brown@xxxxxxxxx>
Cc: x86@xxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
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 4112dbf05f19..9e5c28f3beaa 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 (XFEATURE_MASK_PASID)
diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c
index f2fcdcc979e7..046889f31037 100644
--- a/arch/x86/kernel/fpu/init.c
+++ b/arch/x86/kernel/fpu/init.c
@@ -219,8 +219,12 @@ 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