linux-kernel - [PATCH v15 08/11] x86/mm: Add global ASID process exit helpers

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Message-ID: <20250304135816.12356-9-bp@kernel.org>
Date: Tue,  4 Mar 2025 14:58:13 +0100
From: Borislav Petkov <bp@...nel.org>
To: riel@...riel.com
Cc: Manali.Shukla@....com,
	akpm@...ux-foundation.org,
	andrew.cooper3@...rix.com,
	jackmanb@...gle.com,
	jannh@...gle.com,
	kernel-team@...a.com,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org,
	mhklinux@...look.com,
	nadav.amit@...il.com,
	thomas.lendacky@....com,
	x86@...nel.org,
	zhengqi.arch@...edance.com,
	Borislav Petkov <bp@...en8.de>
Subject: [PATCH v15 08/11] x86/mm: Add global ASID process exit helpers

From: Rik van Riel <riel@...riel.com>

A global ASID is allocated for the lifetime of a process. Free the global ASID
at process exit time.

  [ bp: Massage, create helpers, hide details inside them. ]

Signed-off-by: Rik van Riel <riel@...riel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
Link: https://lore.kernel.org/r/20250226030129.530345-10-riel@surriel.com
---
 arch/x86/include/asm/mmu_context.h | 8 +++++++-
 arch/x86/include/asm/tlbflush.h    | 9 +++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h
index a2c70e495b1b..2398058b6e83 100644
--- a/arch/x86/include/asm/mmu_context.h
+++ b/arch/x86/include/asm/mmu_context.h
@@ -2,7 +2,6 @@
 #ifndef _ASM_X86_MMU_CONTEXT_H
 #define _ASM_X86_MMU_CONTEXT_H
 
-#include <asm/desc.h>
 #include <linux/atomic.h>
 #include <linux/mm_types.h>
 #include <linux/pkeys.h>
@@ -13,6 +12,7 @@
 #include <asm/paravirt.h>
 #include <asm/debugreg.h>
 #include <asm/gsseg.h>
+#include <asm/desc.h>
 
 extern atomic64_t last_mm_ctx_id;
 
@@ -139,6 +139,9 @@ 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);
 
+#define mm_init_global_asid mm_init_global_asid
+extern void mm_init_global_asid(struct mm_struct *mm);
+
 extern void mm_free_global_asid(struct mm_struct *mm);
 
 /*
@@ -163,6 +166,8 @@ static inline int init_new_context(struct task_struct *tsk,
 		mm->context.execute_only_pkey = -1;
 	}
 #endif
+
+	mm_init_global_asid(mm);
 	mm_reset_untag_mask(mm);
 	init_new_context_ldt(mm);
 	return 0;
@@ -172,6 +177,7 @@ static inline int init_new_context(struct task_struct *tsk,
 static inline void destroy_context(struct mm_struct *mm)
 {
 	destroy_context_ldt(mm);
+	mm_free_global_asid(mm);
 }
 
 extern void switch_mm(struct mm_struct *prev, struct mm_struct *next,
diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
index 1f61a39a8776..e6c3be06dd21 100644
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -261,6 +261,14 @@ static inline u16 mm_global_asid(struct mm_struct *mm)
 	return asid;
 }
 
+static inline void mm_init_global_asid(struct mm_struct *mm)
+{
+	if (cpu_feature_enabled(X86_FEATURE_INVLPGB)) {
+		mm->context.global_asid = 0;
+		mm->context.asid_transition = false;
+	}
+}
+
 static inline void mm_assign_global_asid(struct mm_struct *mm, u16 asid)
 {
 	/*
@@ -281,6 +289,7 @@ static inline bool mm_in_asid_transition(struct mm_struct *mm)
 }
 #else
 static inline u16 mm_global_asid(struct mm_struct *mm) { return 0; }
+static inline void mm_init_global_asid(struct mm_struct *mm) { }
 static inline void mm_assign_global_asid(struct mm_struct *mm, u16 asid) { }
 static inline bool mm_in_asid_transition(struct mm_struct *mm) { return false; }
 #endif /* CONFIG_BROADCAST_TLB_FLUSH */
-- 
2.43.0