linux-kernel - [PATCH 03/11] x86/mm: get INVLPGB count max from CPUID

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Message-ID: <20241223025751.3268975-4-riel@surriel.com>
Date: Sun, 22 Dec 2024 21:55:09 -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,
	linux-mm@...ck.org,
	Rik van Riel <riel@...riel.com>
Subject: [PATCH 03/11] x86/mm: 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/tlbflush.h | 1 +
 arch/x86/kernel/cpu/amd.c       | 8 ++++++++
 arch/x86/kernel/setup.c         | 4 ++++
 3 files changed, 13 insertions(+)

diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
index 02fc2aa06e9e..7d1468a3967b 100644
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -182,6 +182,7 @@ static inline void cr4_init_shadow(void)
 
 extern unsigned long mmu_cr4_features;
 extern u32 *trampoline_cr4_features;
+extern u16 invlpgb_count_max;
 
 extern void initialize_tlbstate_and_flush(void);
 
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 79d2e17f6582..226b8fc64bfc 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 */
+	invlpgb_count_max = (edx & 0xffff) + 1;
 }
 
 static const struct cpu_dev amd_cpu_dev = {
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index f1fea506e20f..ef2b49edca25 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -138,6 +138,10 @@ __visible unsigned long mmu_cr4_features __ro_after_init;
 __visible unsigned long mmu_cr4_features __ro_after_init = X86_CR4_PAE;
 #endif
 
+#ifdef CONFIG_CPU_SUP_AMD
+u16 invlpgb_count_max;
+#endif
+
 #ifdef CONFIG_IMA
 static phys_addr_t ima_kexec_buffer_phys;
 static size_t ima_kexec_buffer_size;
-- 
2.47.1