[PATCH v13 09/14] x86/mm: global ASID process exit helpers

Rik van Riel
2025-02-23T19:50:13Z

A global ASID is allocated for the lifetime of a process.

Free the global ASID at process exit time.

Signed-off-by: Rik van Riel <riel@surriel.com>
---
arch/x86/include/asm/mmu_context.h | 14 ++++++++++++++
1 file changed, 14 insertions(+)

diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h
index 795fdd53bd0a..d670699d32c2 100644
--- a/arch/x86/include/asm/mmu_context.h
+++ b/arch/x86/include/asm/mmu_context.h
@@ -139,6 +139,8 @@ static inline void mm_reset_untag_mask(struct mm_struct *mm)
#define enter_lazy_tlb enter_lazy_tlb
extern void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk);

+extern void destroy_context_free_global_asid(struct mm_struct *mm);
+
/*
* Init a new mm. Used on mm copies, like at fork()
* and on mm's that are brand-new, like at execve().
@@ -161,6 +163,14 @@ static inline int init_new_context(struct task_struct *tsk,
mm->context.execute_only_pkey = -1;
}
#endif
+
+#ifdef CONFIG_X86_BROADCAST_TLB_FLUSH
+ if (cpu_feature_enabled(X86_FEATURE_INVLPGB)) {
+ mm->context.global_asid = 0;
+ mm->context.asid_transition = false;
+ }
+#endif
+
mm_reset_untag_mask(mm);
init_new_context_ldt(mm);
return 0;
@@ -170,6 +180,10 @@ static inline int init_new_context(struct task_struct *tsk,
static inline void destroy_context(struct mm_struct *mm)
{
destroy_context_ldt(mm);
+#ifdef CONFIG_X86_BROADCAST_TLB_FLUSH
+ if (cpu_feature_enabled(X86_FEATURE_INVLPGB))
+ destroy_context_free_global_asid(mm);
+#endif
}

extern void switch_mm(struct mm_struct *prev, struct mm_struct *next,
--
2.47.1