linux-kernel - [PATCH 1/3] x86/mm: Unexport tlb_state

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Message-ID: <20250520110632.054673615@infradead.org>
Date: Tue, 20 May 2025 12:55:43 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: x86@...nel.org
Cc: linux-kernel@...r.kernel.org,
 peterz@...radead.org,
 kys@...rosoft.com,
 haiyangz@...rosoft.com,
 wei.liu@...nel.org,
 decui@...rosoft.com,
 tglx@...utronix.de,
 mingo@...hat.com,
 bp@...en8.de,
 dave.hansen@...ux.intel.com,
 hpa@...or.com,
 luto@...nel.org,
 linux-hyperv@...r.kernel.org
Subject: [PATCH 1/3] x86/mm: Unexport tlb_state_shared

Never export data; modules have no business being able to change tlb
state.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 arch/x86/hyperv/mmu.c           |    9 ++-------
 arch/x86/include/asm/tlbflush.h |    2 ++
 arch/x86/mm/tlb.c               |    7 ++++++-
 3 files changed, 10 insertions(+), 8 deletions(-)

--- a/arch/x86/hyperv/mmu.c
+++ b/arch/x86/hyperv/mmu.c
@@ -51,11 +51,6 @@ static inline int fill_gva_list(u64 gva_
 	return gva_n - offset;
 }
 
-static bool cpu_is_lazy(int cpu)
-{
-	return per_cpu(cpu_tlbstate_shared.is_lazy, cpu);
-}
-
 static void hyperv_flush_tlb_multi(const struct cpumask *cpus,
 				   const struct flush_tlb_info *info)
 {
@@ -113,7 +108,7 @@ static void hyperv_flush_tlb_multi(const
 			goto do_ex_hypercall;
 
 		for_each_cpu(cpu, cpus) {
-			if (do_lazy && cpu_is_lazy(cpu))
+			if (do_lazy && cpu_tlbstate_is_lazy(cpu))
 				continue;
 			vcpu = hv_cpu_number_to_vp_number(cpu);
 			if (vcpu == VP_INVAL) {
@@ -198,7 +193,7 @@ static u64 hyperv_flush_tlb_others_ex(co
 
 	flush->hv_vp_set.format = HV_GENERIC_SET_SPARSE_4K;
 	nr_bank = cpumask_to_vpset_skip(&flush->hv_vp_set, cpus,
-			info->freed_tables ? NULL : cpu_is_lazy);
+			info->freed_tables ? NULL : cpu_tlbstate_is_lazy);
 	if (nr_bank < 0)
 		return HV_STATUS_INVALID_PARAMETER;
 
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -172,6 +172,8 @@ struct tlb_state_shared {
 };
 DECLARE_PER_CPU_SHARED_ALIGNED(struct tlb_state_shared, cpu_tlbstate_shared);
 
+bool cpu_tlbstate_is_lazy(int cpu);
+
 bool nmi_uaccess_okay(void);
 #define nmi_uaccess_okay nmi_uaccess_okay
 
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -1322,7 +1322,12 @@ static bool should_trim_cpumask(struct m
 }
 
 DEFINE_PER_CPU_SHARED_ALIGNED(struct tlb_state_shared, cpu_tlbstate_shared);
-EXPORT_PER_CPU_SYMBOL(cpu_tlbstate_shared);
+
+bool cpu_tlbstate_is_lazy(int cpu)
+{
+	return per_cpu(cpu_tlbstate_shared.is_lazy, cpu);
+}
+EXPORT_SYMBOL_GPL(cpu_tlbstate_is_lazy);
 
 STATIC_NOPV void native_flush_tlb_multi(const struct cpumask *cpumask,
 					 const struct flush_tlb_info *info)