linux-kernel - [PATCH RFC 04/14] arm64/mm: Move the variable lock and tlb_flush_pending to asid

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Date:   Thu, 21 Mar 2019 16:36:13 +0000
From:   Julien Grall <julien.grall@....com>
To:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        kvmarm@...ts.cs.columbia.edu
Cc:     christoffer.dall@....com, james.morse@....com,
        marc.zyngier@....com, julien.thierry@....com,
        suzuki.poulose@....com, catalin.marinas@....com,
        will.deacon@....com, Julien Grall <julien.grall@....com>,
        Julien Grall <julien.gralL@....com>
Subject: [PATCH RFC 04/14] arm64/mm: Move the variable lock and tlb_flush_pending to asid_info

The variables lock and tlb_flush_pending holds information for a given
ASID allocator. So move them to the asid_info structure.

Signed-off-by: Julien Grall <julien.gralL@....com>
---
 arch/arm64/mm/context.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/mm/context.c b/arch/arm64/mm/context.c
index da17ed6c7117..e98ab348b9cb 100644
--- a/arch/arm64/mm/context.c
+++ b/arch/arm64/mm/context.c
@@ -27,8 +27,6 @@
 #include <asm/smp.h>
 #include <asm/tlbflush.h>
 
-static DEFINE_RAW_SPINLOCK(cpu_asid_lock);
-
 struct asid_info
 {
 	atomic64_t	generation;
@@ -36,6 +34,9 @@ struct asid_info
 	atomic64_t __percpu	*active;
 	u64 __percpu		*reserved;
 	u32			bits;
+	raw_spinlock_t		lock;
+	/* Which CPU requires context flush on next call */
+	cpumask_t		flush_pending;
 } asid_info;
 
 #define active_asid(info, cpu)	*per_cpu_ptr((info)->active, cpu)
@@ -44,8 +45,6 @@ struct asid_info
 static DEFINE_PER_CPU(atomic64_t, active_asids);
 static DEFINE_PER_CPU(u64, reserved_asids);
 
-static cpumask_t tlb_flush_pending;
-
 #define ASID_MASK(info)			(~GENMASK((info)->bits - 1, 0))
 #define ASID_FIRST_VERSION(info)	(1UL << ((info)->bits))
 
@@ -124,7 +123,7 @@ static void flush_context(struct asid_info *info)
 	 * Queue a TLB invalidation for each CPU to perform on next
 	 * context-switch
 	 */
-	cpumask_setall(&tlb_flush_pending);
+	cpumask_setall(&info->flush_pending);
 }
 
 static bool check_update_reserved_asid(struct asid_info *info, u64 asid,
@@ -233,7 +232,7 @@ void check_and_switch_context(struct mm_struct *mm, unsigned int cpu)
 				     old_active_asid, asid))
 		goto switch_mm_fastpath;
 
-	raw_spin_lock_irqsave(&cpu_asid_lock, flags);
+	raw_spin_lock_irqsave(&info->lock, flags);
 	/* Check that our ASID belongs to the current generation. */
 	asid = atomic64_read(&mm->context.id);
 	if ((asid ^ atomic64_read(&info->generation)) >> info->bits) {
@@ -241,11 +240,11 @@ void check_and_switch_context(struct mm_struct *mm, unsigned int cpu)
 		atomic64_set(&mm->context.id, asid);
 	}
 
-	if (cpumask_test_and_clear_cpu(cpu, &tlb_flush_pending))
+	if (cpumask_test_and_clear_cpu(cpu, &info->flush_pending))
 		local_flush_tlb_all();
 
 	atomic64_set(&active_asid(info, cpu), asid);
-	raw_spin_unlock_irqrestore(&cpu_asid_lock, flags);
+	raw_spin_unlock_irqrestore(&info->lock, flags);
 
 switch_mm_fastpath:
 
@@ -288,6 +287,8 @@ static int asids_init(void)
 	info->active = &active_asids;
 	info->reserved = &reserved_asids;
 
+	raw_spin_lock_init(&info->lock);
+
 	pr_info("ASID allocator initialised with %lu entries\n",
 		NUM_USER_ASIDS(info));
 	return 0;
-- 
2.11.0