Commit 70c3f167 authored by Chang S. Bae's avatar Chang S. Bae Committed by Borislav Petkov
Browse files

x86/fpu/xstate: Prepare XSAVE feature table for gaps in state component numbers 



The kernel checks at boot time which features are available by walking a
XSAVE feature table which contains the CPUID feature bit numbers which need
to be checked whether a feature is available on a CPU or not. So far the
feature numbers have been linear, but AMX will create a gap which the
current code cannot handle.

Make the table entries explicitly indexed and adjust the loop code
accordingly to prepare for that.

No functional change.

Signed-off-by: default avatarChang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarLen Brown <len.brown@intel.com>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20211021225527.10184-20-chang.seok.bae@intel.com
parent 500afbf6

arch/x86/kernel/fpu/xstate.c

+16 −13
Original line number Diff line number Diff line
@@ -53,18 +53,18 @@ static const char *xfeature_names[] = 
	"unknown xstate feature"	,

};



static short xsave_cpuid_features[] __initdata = {

	X86_FEATURE_FPU,

	X86_FEATURE_XMM,

	X86_FEATURE_AVX,

	X86_FEATURE_MPX,

	X86_FEATURE_MPX,

	X86_FEATURE_AVX512F,

	X86_FEATURE_AVX512F,

	X86_FEATURE_AVX512F,

	X86_FEATURE_INTEL_PT,

	X86_FEATURE_PKU,

	X86_FEATURE_ENQCMD,

static unsigned short xsave_cpuid_features[] __initdata = {

	[XFEATURE_FP]				= X86_FEATURE_FPU,

	[XFEATURE_SSE]				= X86_FEATURE_XMM,

	[XFEATURE_YMM]				= X86_FEATURE_AVX,

	[XFEATURE_BNDREGS]			= X86_FEATURE_MPX,

	[XFEATURE_BNDCSR]			= X86_FEATURE_MPX,

	[XFEATURE_OPMASK]			= X86_FEATURE_AVX512F,

	[XFEATURE_ZMM_Hi256]			= X86_FEATURE_AVX512F,

	[XFEATURE_Hi16_ZMM]			= X86_FEATURE_AVX512F,

	[XFEATURE_PT_UNIMPLEMENTED_SO_FAR]	= X86_FEATURE_INTEL_PT,

	[XFEATURE_PKRU]				= X86_FEATURE_PKU,

	[XFEATURE_PASID]			= X86_FEATURE_ENQCMD,

};



static unsigned int xstate_offsets[XFEATURE_MAX] __ro_after_init =
@@ -809,7 +809,10 @@ void __init fpu__init_system_xstate(unsigned int legacy_size) 
	 * Clear XSAVE features that are disabled in the normal CPUID.

	 */

	for (i = 0; i < ARRAY_SIZE(xsave_cpuid_features); i++) {

		if (!boot_cpu_has(xsave_cpuid_features[i]))

		unsigned short cid = xsave_cpuid_features[i];



		/* Careful: X86_FEATURE_FPU is 0! */

		if ((i != XFEATURE_FP && !cid) || !boot_cpu_has(cid))

			fpu_kernel_cfg.max_features &= ~BIT_ULL(i);

	}