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Date: Fri, 16 Dec 2016 10:35:26 -0800
From: Mike Kravetz <mike.kravetz@...cle.com>
To: sparclinux@...r.kernel.org, linux-mm@...ck.org,
linux-kernel@...r.kernel.org
Cc: "David S . Miller" <davem@...emloft.net>,
Bob Picco <bob.picco@...cle.com>,
Nitin Gupta <nitin.m.gupta@...cle.com>,
Vijay Kumar <vijay.ac.kumar@...cle.com>,
Julian Calaby <julian.calaby@...il.com>,
Adam Buchbinder <adam.buchbinder@...il.com>,
"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
Michal Hocko <mhocko@...e.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Mike Kravetz <mike.kravetz@...cle.com>
Subject: [RFC PATCH 03/14] sparc64: routines for basic mmu shared context structure management
Add routines for basic management of mmu shared context data structures.
These routines have to do with allocation/deallocation and get/put
of the structures. The structures themselves will come from a new
kmem cache.
FIXMEs were added to then code where additional work is needed.
Signed-off-by: Mike Kravetz <mike.kravetz@...cle.com>
---
arch/sparc/include/asm/mmu_context_64.h | 6 +++
arch/sparc/include/asm/tlb_64.h | 3 ++
arch/sparc/include/asm/tsb.h | 2 +
arch/sparc/kernel/smp_64.c | 22 +++++++++
arch/sparc/mm/init_64.c | 84 +++++++++++++++++++++++++++++++--
arch/sparc/mm/tsb.c | 54 +++++++++++++++++++++
6 files changed, 168 insertions(+), 3 deletions(-)
diff --git a/arch/sparc/include/asm/mmu_context_64.h b/arch/sparc/include/asm/mmu_context_64.h
index d031799..acaea6d 100644
--- a/arch/sparc/include/asm/mmu_context_64.h
+++ b/arch/sparc/include/asm/mmu_context_64.h
@@ -18,6 +18,12 @@ extern unsigned long tlb_context_cache;
extern unsigned long mmu_context_bmap[];
void get_new_mmu_context(struct mm_struct *mm);
+#if defined(CONFIG_SHARED_MMU_CTX)
+void get_new_mmu_shared_context(struct mm_struct *mm);
+void put_shared_context(struct mm_struct *mm);
+void set_mm_shared_ctx(struct mm_struct *mm, struct shared_mmu_ctx *ctx);
+void destroy_shared_context(struct mm_struct *mm);
+#endif
#ifdef CONFIG_SMP
void smp_new_mmu_context_version(void);
#else
diff --git a/arch/sparc/include/asm/tlb_64.h b/arch/sparc/include/asm/tlb_64.h
index 4cb392f..e348a1b 100644
--- a/arch/sparc/include/asm/tlb_64.h
+++ b/arch/sparc/include/asm/tlb_64.h
@@ -14,6 +14,9 @@ void smp_flush_tlb_pending(struct mm_struct *,
#ifdef CONFIG_SMP
void smp_flush_tlb_mm(struct mm_struct *mm);
+#if defined(CONFIG_SHARED_MMU_CTX)
+void smp_flush_shared_tlb_mm(struct mm_struct *mm);
+#endif
#define do_flush_tlb_mm(mm) smp_flush_tlb_mm(mm)
#else
#define do_flush_tlb_mm(mm) __flush_tlb_mm(CTX_HWBITS(mm->context), SECONDARY_CONTEXT)
diff --git a/arch/sparc/include/asm/tsb.h b/arch/sparc/include/asm/tsb.h
index 32258e0..311cd4e 100644
--- a/arch/sparc/include/asm/tsb.h
+++ b/arch/sparc/include/asm/tsb.h
@@ -72,6 +72,8 @@ struct tsb_phys_patch_entry {
unsigned int insn;
};
extern struct tsb_phys_patch_entry __tsb_phys_patch, __tsb_phys_patch_end;
+
+extern struct kmem_cache *shared_mmu_ctx_cachep __read_mostly;
#endif
#define TSB_LOAD_QUAD(TSB, REG) \
661: ldda [TSB] ASI_NUCLEUS_QUAD_LDD, REG; \
diff --git a/arch/sparc/kernel/smp_64.c b/arch/sparc/kernel/smp_64.c
index 8182f7c..c0f23ee 100644
--- a/arch/sparc/kernel/smp_64.c
+++ b/arch/sparc/kernel/smp_64.c
@@ -1078,6 +1078,28 @@ void smp_flush_tlb_mm(struct mm_struct *mm)
put_cpu();
}
+#if defined(CONFIG_SHARED_MMU_CTX)
+/*
+ * Called when last reference to shared context is dropped. Flush
+ * all TLB entries associated with the shared clontext ID.
+ *
+ * FIXME
+ * Future optimization would be to store cpumask in shared context
+ * structure and only make cross call to those cpus.
+ */
+void smp_flush_shared_tlb_mm(struct mm_struct *mm)
+{
+ u32 ctx = SHARED_CTX_HWBITS(mm->context);
+
+ (void)get_cpu(); /* prevent preemption */
+
+ smp_cross_call(&xcall_flush_tlb_mm, ctx, 0, 0);
+ __flush_tlb_mm(ctx, SECONDARY_CONTEXT);
+
+ put_cpu();
+}
+#endif
+
struct tlb_pending_info {
unsigned long ctx;
unsigned long nr;
diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c
index 37aa537..bb9a6ee 100644
--- a/arch/sparc/mm/init_64.c
+++ b/arch/sparc/mm/init_64.c
@@ -673,14 +673,24 @@ DECLARE_BITMAP(mmu_context_bmap, MAX_CTX_NR);
*
* Always invoked with interrupts disabled.
*/
-void get_new_mmu_context(struct mm_struct *mm)
+static void __get_new_mmu_context_common(struct mm_struct *mm, bool shared)
{
unsigned long ctx, new_ctx;
unsigned long orig_pgsz_bits;
int new_version;
spin_lock(&ctx_alloc_lock);
- orig_pgsz_bits = (mm->context.sparc64_ctx_val & CTX_PGSZ_MASK);
+#if defined(CONFIG_SHARED_MMU_CTX)
+ if (shared)
+ /*
+ * Note that we are only called from get_new_mmu_shared_context
+ * which guarantees the existence of shared_ctx structure.
+ */
+ orig_pgsz_bits = (mm->context.shared_ctx->shared_ctx_val &
+ CTX_PGSZ_MASK);
+ else
+#endif
+ orig_pgsz_bits = (mm->context.sparc64_ctx_val & CTX_PGSZ_MASK);
ctx = (tlb_context_cache + 1) & CTX_NR_MASK;
new_ctx = find_next_zero_bit(mmu_context_bmap, 1 << CTX_NR_BITS, ctx);
new_version = 0;
@@ -714,13 +724,81 @@ void get_new_mmu_context(struct mm_struct *mm)
new_ctx |= (tlb_context_cache & CTX_VERSION_MASK);
out:
tlb_context_cache = new_ctx;
- mm->context.sparc64_ctx_val = new_ctx | orig_pgsz_bits;
+#if defined(CONFIG_SHARED_MMU_CTX)
+ if (shared)
+ mm->context.shared_ctx->shared_ctx_val =
+ new_ctx | orig_pgsz_bits;
+ else
+#endif
+ mm->context.sparc64_ctx_val = new_ctx | orig_pgsz_bits;
spin_unlock(&ctx_alloc_lock);
+ /*
+ * FIXME
+ * Not sure if the case where a shared context ID changed (not just
+ * newly allocated) is handled properly. May need to modify
+ * smp_new_mmu_context_version to handle correctly.
+ */
if (unlikely(new_version))
smp_new_mmu_context_version();
}
+void get_new_mmu_context(struct mm_struct *mm)
+{
+ __get_new_mmu_context_common(mm, false);
+}
+
+#if defined(CONFIG_SHARED_MMU_CTX)
+void get_new_mmu_shared_context(struct mm_struct *mm)
+{
+ /*
+ * For now, we only support one shared context mapping per mm. So,
+ * if mm->context.shared_ctx is already set, we have a bug
+ *
+ * Note that we are called from mmap with mmap_sem held. Thus,
+ * there can not be two threads racing to initialize.
+ */
+ BUG_ON(mm->context.shared_ctx);
+
+ mm->context.shared_ctx = kmem_cache_alloc(shared_mmu_ctx_cachep,
+ GFP_NOWAIT);
+ if (!mm->context.shared_ctx)
+ return;
+
+ __get_new_mmu_context_common(mm, true);
+}
+
+void put_shared_context(struct mm_struct *mm)
+{
+ if (!mm->context.shared_ctx)
+ return;
+
+ if (atomic_dec_and_test(&mm->context.shared_ctx->refcount)) {
+ smp_flush_shared_tlb_mm(mm);
+ destroy_shared_context(mm);
+ kmem_cache_free(shared_mmu_ctx_cachep, mm->context.shared_ctx);
+ }
+
+ /*
+ * For now we assume/expect only one shared context reference per mm
+ */
+ mm->context.shared_ctx = NULL;
+}
+
+void set_mm_shared_ctx(struct mm_struct *mm, struct shared_mmu_ctx *ctx)
+{
+ BUG_ON(mm->context.shared_ctx || !ctx);
+
+ /*
+ * Note that we are called with mmap_lock held on underlying
+ * mapping. Hence, the ctx structure pointed to by the matching
+ * vma can not go away.
+ */
+ atomic_inc(&ctx->refcount);
+ mm->context.shared_ctx = ctx;
+}
+#endif
+
static int numa_enabled = 1;
static int numa_debug;
diff --git a/arch/sparc/mm/tsb.c b/arch/sparc/mm/tsb.c
index e20fbba..8c2d148 100644
--- a/arch/sparc/mm/tsb.c
+++ b/arch/sparc/mm/tsb.c
@@ -277,6 +277,8 @@ static void setup_tsb_params(struct mm_struct *mm, unsigned long tsb_idx, unsign
}
}
+struct kmem_cache *shared_mmu_ctx_cachep __read_mostly;
+
struct kmem_cache *pgtable_cache __read_mostly;
static struct kmem_cache *tsb_caches[8] __read_mostly;
@@ -292,6 +294,27 @@ static const char *tsb_cache_names[8] = {
"tsb_1MB",
};
+#if defined(CONFIG_SHARED_MMU_CTX)
+static void init_once_shared_mmu_ctx(void *mem)
+{
+ struct shared_mmu_ctx *ctx = (struct shared_mmu_ctx *) mem;
+
+ ctx->shared_ctx_val = 0;
+ atomic_set(&ctx->refcount, 1);
+}
+
+static void __init sun4v_shared_mmu_ctx_init(void)
+{
+ shared_mmu_ctx_cachep = kmem_cache_create("shared_mmu_ctx_cache",
+ sizeof(struct shared_mmu_ctx),
+ 0,
+ SLAB_HWCACHE_ALIGN|SLAB_PANIC,
+ init_once_shared_mmu_ctx);
+}
+#else
+static void __init sun4v_shared_mmu_ctx_init(void) { }
+#endif
+
void __init pgtable_cache_init(void)
{
unsigned long i;
@@ -317,6 +340,13 @@ void __init pgtable_cache_init(void)
prom_halt();
}
}
+
+ if (tlb_type == hypervisor)
+ /*
+ * FIXME - shared context enables/supported on most
+ * but not all sun4v priocessors
+ */
+ sun4v_shared_mmu_ctx_init();
}
int sysctl_tsb_ratio = -2;
@@ -547,6 +577,30 @@ static void tsb_destroy_one(struct tsb_config *tp)
tp->tsb_reg_val = 0UL;
}
+#if defined(CONFIG_SHARED_MMU_CTX)
+void destroy_shared_context(struct mm_struct *mm)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&ctx_alloc_lock, flags);
+
+ if (SHARED_CTX_VALID(mm->context)) {
+ unsigned long nr = SHARED_CTX_NRBITS(mm->context);
+
+ mmu_context_bmap[nr>>6] &= ~(1UL << (nr & 63));
+ }
+
+ spin_unlock_irqrestore(&ctx_alloc_lock, flags);
+
+#if defined(CONFIG_SHARED_MMU_CTX)
+ /*
+ * Any shared context should have been cleaned up by now
+ */
+ BUG_ON(SHARED_CTX_VALID(mm->context));
+#endif
+}
+#endif
+
void destroy_context(struct mm_struct *mm)
{
unsigned long flags, i;
--
2.7.4
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