linux-kernel - [PATCH 02/10] x86,tlb: get INVLPGB count max from CPUID

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Message-ID: <20241222040717.3096835-3-riel@surriel.com>
Date: Sat, 21 Dec 2024 23:06:34 -0500
From: Rik van Riel <riel@...riel.com>
To: x86@...nel.org
Cc: linux-kernel@...r.kernel.org,
	kernel-team@...a.com,
	dave.hansen@...ux.intel.com,
	luto@...nel.org,
	peterz@...radead.org,
	tglx@...utronix.de,
	mingo@...hat.com,
	bp@...en8.de,
	hpa@...or.com,
	akpm@...ux-foundation.org,
	Rik van Riel <riel@...riel.com>
Subject: [PATCH 02/10] x86,tlb: get INVLPGB count max from CPUID

The CPU advertises the maximum number of pages that can be shot down
with one INVLPGB instruction in the CPUID data.

Save that information for later use.

Signed-off-by: Rik van Riel <riel@...riel.com>
---
 arch/x86/include/asm/processor.h | 2 ++
 arch/x86/kernel/cpu/amd.c        | 8 ++++++++
 2 files changed, 10 insertions(+)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 20e6009381ed..dd32a75d5da8 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -185,6 +185,8 @@ struct cpuinfo_x86 {
 	u16			booted_cores;
 	/* Index into per_cpu list: */
 	u16			cpu_index;
+	/* Max number of pages invalidated with one INVLPGB */
+	u16			invlpgb_count_max;
 	/*  Is SMT active on this core? */
 	bool			smt_active;
 	u32			microcode;
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 79d2e17f6582..6a6adbe9ae54 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -1135,6 +1135,14 @@ static void cpu_detect_tlb_amd(struct cpuinfo_x86 *c)
 		tlb_lli_2m[ENTRIES] = eax & mask;
 
 	tlb_lli_4m[ENTRIES] = tlb_lli_2m[ENTRIES] >> 1;
+
+	if (c->extended_cpuid_level < 0x80000008)
+		return;
+
+	cpuid(0x80000008, &eax, &ebx, &ecx, &edx);
+
+	/* Max number of pages INVLPGB can invalidate in one shot */
+	c->invlpgb_count_max = (edx & 0xffff) + 1;
 }
 
 static const struct cpu_dev amd_cpu_dev = {
-- 
2.47.1