Commit 2308ee57 authored by Chang S. Bae's avatar Chang S. Bae Committed by Borislav Petkov
Browse files

x86/fpu/amx: Enable the AMX feature in 64-bit mode 



Add the AMX state components in XFEATURE_MASK_USER_SUPPORTED and the
TILE_DATA component to the dynamic states and update the permission check
table accordingly.

This is only effective on 64 bit kernels as for 32bit kernels
XFEATURE_MASK_TILE is defined as 0.

TILE_DATA is caller-saved state and the only dynamic state. Add build time
sanity check to ensure the assumption that every dynamic feature is caller-
saved.

Make AMX state depend on XFD as it is dynamic feature.

Signed-off-by: default avatarChang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20211021225527.10184-24-chang.seok.bae@intel.com
parent db3e7321

arch/x86/include/asm/fpu/xstate.h

+3 −2
Original line number Diff line number Diff line
@@ -35,7 +35,8 @@ 
				      XFEATURE_MASK_Hi16_ZMM	 | \

				      XFEATURE_MASK_PKRU | \

				      XFEATURE_MASK_BNDREGS | \

				      XFEATURE_MASK_BNDCSR)

				      XFEATURE_MASK_BNDCSR | \

				      XFEATURE_MASK_XTILE)



/*

 * Features which are restored when returning to user space.
@@ -46,7 +47,7 @@ 
	(XFEATURE_MASK_USER_SUPPORTED & ~XFEATURE_MASK_PKRU)



/* Features which are dynamically enabled for a process on request */

#define XFEATURE_MASK_USER_DYNAMIC	0ULL

#define XFEATURE_MASK_USER_DYNAMIC	XFEATURE_MASK_XTILE_DATA



/* All currently supported supervisor features */

#define XFEATURE_MASK_SUPERVISOR_SUPPORTED (XFEATURE_MASK_PASID)

arch/x86/kernel/cpu/cpuid-deps.c

+1 −0
Original line number Diff line number Diff line
@@ -76,6 +76,7 @@ static const struct cpuid_dep cpuid_deps[] = { 
	{ X86_FEATURE_SGX1,			X86_FEATURE_SGX       },

	{ X86_FEATURE_SGX2,			X86_FEATURE_SGX1      },

	{ X86_FEATURE_XFD,			X86_FEATURE_XSAVES    },

	{ X86_FEATURE_AMX_TILE,			X86_FEATURE_XFD       },

	{}

};

arch/x86/kernel/fpu/core.c

+6 −0
Original line number Diff line number Diff line
@@ -494,6 +494,12 @@ int fpu_clone(struct task_struct *dst, unsigned long clone_flags) 
		return 0;

	}



	/*

	 * If a new feature is added, ensure all dynamic features are

	 * caller-saved from here!

	 */

	BUILD_BUG_ON(XFEATURE_MASK_USER_DYNAMIC != XFEATURE_MASK_XTILE_DATA);



	/*

	 * Save the default portion of the current FPU state into the

	 * clone. Assume all dynamic features to be defined as caller-

arch/x86/kernel/fpu/xstate.c

+3 −2
Original line number Diff line number Diff line
@@ -404,7 +404,8 @@ static __init void os_xrstor_booting(struct xregs_state *xstate) 
	 XFEATURE_MASK_PKRU |			\

	 XFEATURE_MASK_BNDREGS |		\

	 XFEATURE_MASK_BNDCSR |			\

	 XFEATURE_MASK_PASID)

	 XFEATURE_MASK_PASID |			\

	 XFEATURE_MASK_XTILE)



/*

 * setup the xstate image representing the init state
@@ -1636,7 +1637,7 @@ static int __xstate_request_perm(u64 permitted, u64 requested) 
 * Permissions array to map facilities with more than one component

 */

static const u64 xstate_prctl_req[XFEATURE_MAX] = {

	/* [XFEATURE_XTILE_DATA] = XFEATURE_MASK_XTILE, */

	[XFEATURE_XTILE_DATA] = XFEATURE_MASK_XTILE_DATA,

};



static int xstate_request_perm(unsigned long idx)