Merge tag 'x86_fpu_for_v5.17_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 fpu update from Borislav Petkov:
 "A single x86/fpu update for 5.17:

   - Exclude AVX opmask registers use from AVX512 state tracking as they
     don't contribute to frequency throttling"

* tag 'x86_fpu_for_v5.17_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/fpu: Correct AVX512 state tracking

1 files changed, 14 insertions, 7 deletions

diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index 8ea306b1bf8e..dd3777ac0443 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -99,6 +99,19 @@ bool irq_fpu_usable(void)
 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
  * preserved.
  *
@@ -116,13 +129,7 @@ void save_fpregs_to_fpstate(struct fpu *fpu)
 {
 	if (likely(use_xsave())) {
 		os_xsave(fpu->fpstate);
-
-		/*
-		 * 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;
+		update_avx_timestamp(fpu);
 		return;
 	}