linux-kernel - [PATCH 3/3] x86/apic: Convert the TSC deadline timer matching to steppings macro

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Date:   Wed,  6 May 2020 09:15:16 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     X86 ML <x86@...nel.org>
Cc:     Mark Gross <mgross@...ux.intel.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>
Subject: [PATCH 3/3] x86/apic: Convert the TSC deadline timer matching to steppings macro

From: Borislav Petkov <bp@...e.de>

... and get rid of the function pointers which would spit out the
microcode revision based on the CPU stepping.

Signed-off-by: Borislav Petkov <bp@...e.de>
Cc: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 arch/x86/kernel/apic/apic.c | 57 ++++++++-----------------------------
 1 file changed, 12 insertions(+), 45 deletions(-)

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index e53dda210cd7..4b1d31be50b4 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -544,46 +544,20 @@ static struct clock_event_device lapic_clockevent = {
 };
 static DEFINE_PER_CPU(struct clock_event_device, lapic_events);
 
-static __init u32 hsx_deadline_rev(void)
-{
-	switch (boot_cpu_data.x86_stepping) {
-	case 0x02: return 0x3a; /* EP */
-	case 0x04: return 0x0f; /* EX */
-	}
-
-	return ~0U;
-}
-
-static __init u32 bdx_deadline_rev(void)
-{
-	switch (boot_cpu_data.x86_stepping) {
-	case 0x02: return 0x00000011;
-	case 0x03: return 0x0700000e;
-	case 0x04: return 0x0f00000c;
-	case 0x05: return 0x0e000003;
-	}
-
-	return ~0U;
-}
-
-static __init u32 skx_deadline_rev(void)
-{
-	switch (boot_cpu_data.x86_stepping) {
-	case 0x03: return 0x01000136;
-	case 0x04: return 0x02000014;
-	}
+static const struct x86_cpu_id deadline_match[] __initconst = {
+	X86_MATCH_INTEL_FAM6_MODEL_STEPPINGS(HASWELL_X, X86_STEPPINGS(0x2, 0x2), 0x3a), /* EP */
+	X86_MATCH_INTEL_FAM6_MODEL_STEPPINGS(HASWELL_X, X86_STEPPINGS(0x4, 0x4), 0x0f), /* EX */
 
-	if (boot_cpu_data.x86_stepping > 4)
-		return 0;
+	X86_MATCH_INTEL_FAM6_MODEL( BROADWELL_X,	0x0b000020),
 
-	return ~0U;
-}
+	X86_MATCH_INTEL_FAM6_MODEL_STEPPINGS(BROADWELL_D, X86_STEPPINGS(0x2, 0x2), 0x00000011),
+	X86_MATCH_INTEL_FAM6_MODEL_STEPPINGS(BROADWELL_D, X86_STEPPINGS(0x3, 0x3), 0x0700000e),
+	X86_MATCH_INTEL_FAM6_MODEL_STEPPINGS(BROADWELL_D, X86_STEPPINGS(0x4, 0x4), 0x0f00000c),
+	X86_MATCH_INTEL_FAM6_MODEL_STEPPINGS(BROADWELL_D, X86_STEPPINGS(0x5, 0x5), 0x0e000003),
 
-static const struct x86_cpu_id deadline_match[] __initconst = {
-	X86_MATCH_INTEL_FAM6_MODEL( HASWELL_X,		&hsx_deadline_rev),
-	X86_MATCH_INTEL_FAM6_MODEL( BROADWELL_X,	0x0b000020),
-	X86_MATCH_INTEL_FAM6_MODEL( BROADWELL_D,	&bdx_deadline_rev),
-	X86_MATCH_INTEL_FAM6_MODEL( SKYLAKE_X,		&skx_deadline_rev),
+	X86_MATCH_INTEL_FAM6_MODEL_STEPPINGS(SKYLAKE_X, X86_STEPPINGS(0x3, 0x3), 0x01000136),
+	X86_MATCH_INTEL_FAM6_MODEL_STEPPINGS(SKYLAKE_X, X86_STEPPINGS(0x4, 0x4), 0x02000014),
+	X86_MATCH_INTEL_FAM6_MODEL_STEPPINGS(SKYLAKE_X, X86_STEPPINGS(0x5, 0xf), 0),
 
 	X86_MATCH_INTEL_FAM6_MODEL( HASWELL,		0x22),
 	X86_MATCH_INTEL_FAM6_MODEL( HASWELL_L,		0x20),
@@ -615,14 +589,7 @@ static __init bool apic_validate_deadline_timer(void)
 	if (!m)
 		return true;
 
-	/*
-	 * Function pointers will have the MSB set due to address layout,
-	 * immediate revisions will not.
-	 */
-	if ((long)m->driver_data < 0)
-		rev = ((u32 (*)(void))(m->driver_data))();
-	else
-		rev = (u32)m->driver_data;
+	rev = (u32)m->driver_data;
 
 	if (boot_cpu_data.microcode >= rev)
 		return true;
-- 
2.21.0