[03/11] x86/mm: get INVLPGB count max from CPUID

Commit Message

Rik van Riel Dec. 23, 2024, 2:55 a.m. UTC

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 <[e-mail]>
---
 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(+)

Patch

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;