Commit 0fe4ff88 authored by Noah Goldstein's avatar Noah Goldstein Committed by Borislav Petkov

x86/fpu: Correct AVX512 state tracking

Add a separate, local mask for tracking AVX512 usage which does not
include the opmask xfeature set. Opmask registers usage does not cause
frequency throttling so it is a completely unnecessary false positive.

While at it, carve it out into a separate function to keep that
abomination extracted out.

 [ bp: Rediff and cleanup ontop of 5.16-rc1. ]
Signed-off-by: default avatarNoah Goldstein <goldstein.w.n@gmail.com>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20210920053951.4093668-1-goldstein.w.n@gmail.com
parent fa55b7dc
...@@ -98,6 +98,19 @@ bool irq_fpu_usable(void) ...@@ -98,6 +98,19 @@ bool irq_fpu_usable(void)
} }
EXPORT_SYMBOL(irq_fpu_usable); EXPORT_SYMBOL(irq_fpu_usable);
/*
* Track AVX512 state use because it is known to slow the max clock
* speed of the core.
*/
static void update_avx_timestamp(struct fpu *fpu)
{
#define AVX512_TRACKING_MASK (XFEATURE_MASK_ZMM_Hi256 | XFEATURE_MASK_Hi16_ZMM)
if (fpu->fpstate->regs.xsave.header.xfeatures & AVX512_TRACKING_MASK)
fpu->avx512_timestamp = jiffies;
}
/* /*
* Save the FPU register state in fpu->fpstate->regs. The register state is * Save the FPU register state in fpu->fpstate->regs. The register state is
* preserved. * preserved.
...@@ -116,13 +129,7 @@ void save_fpregs_to_fpstate(struct fpu *fpu) ...@@ -116,13 +129,7 @@ void save_fpregs_to_fpstate(struct fpu *fpu)
{ {
if (likely(use_xsave())) { if (likely(use_xsave())) {
os_xsave(fpu->fpstate); os_xsave(fpu->fpstate);
update_avx_timestamp(fpu);
/*
* AVX512 state is tracked here because its use is
* known to slow the max clock speed of the core.
*/
if (fpu->fpstate->regs.xsave.header.xfeatures & XFEATURE_MASK_AVX512)
fpu->avx512_timestamp = jiffies;
return; return;
} }
......
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