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Date: Tue, 12 May 2009 17:33:16 -0700
From: Jeremy Fitzhardinge <jeremy@...p.org>
To: "H. Peter Anvin" <hpa@...or.com>
CC: Ingo Molnar <mingo@...e.hu>,
the arch/x86 maintainers <x86@...nel.org>,
Ian Campbell <Ian.Campbell@...rix.com>,
Xen-devel <xen-devel@...ts.xensource.com>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH FIXED] x86: use flush_tlb_others to implement flush_tlb_all
Huh. How's this?
J
Subject: [PATCH] x86: use flush_tlb_others to implement flush_tlb_all
Use the flush_tlb_others() call to implement flush_tlb_all(). This is
useful because flush_tlb_others() already goes via paravirt_ops, and so
will be properly paravirtualized. This needs a small extension of the
extension to the existing native_flush_tlb_others: the global flush is
indicated by setting the "mm" parameter to NULL, so that kernel mappings
are also flushed.
As a side effect of this change, we need to initialize
native_flush_tlb_others()'s spinlocks earlier, as flush_tlb_all() can
be called earlier in the boot sequence.
(Nothing similar is required for xen_flush_tlb_others, as we don't use
global mappings in a guest-visible way under Xen.)
[ Impact: Optimise flush_tlb_all under Xen ]
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>
diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
index 16a5c84..4b663c5 100644
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -89,6 +89,10 @@ static inline void __flush_tlb_one(unsigned long addr)
#ifndef CONFIG_SMP
+static inline void __init init_smp_flush(void)
+{
+}
+
#define flush_tlb() __flush_tlb()
#define flush_tlb_all() __flush_tlb_all()
#define local_flush_tlb() __flush_tlb()
@@ -129,6 +133,8 @@ static inline void reset_lazy_tlbstate(void)
#define local_flush_tlb() __flush_tlb()
+extern void init_smp_flush(void);
+
extern void flush_tlb_all(void);
extern void flush_tlb_current_task(void);
extern void flush_tlb_mm(struct mm_struct *);
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index b415843..747566c 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -87,6 +87,7 @@
#include <asm/cacheflush.h>
#include <asm/processor.h>
#include <asm/bugs.h>
+#include <asm/tlbflush.h>
#include <asm/system.h>
#include <asm/vsyscall.h>
@@ -906,6 +907,9 @@ void __init setup_arch(char **cmdline_p)
initmem_init(0, max_pfn);
+ /* Initialize cross-cpu tlb flushes */
+ init_smp_flush();
+
#ifdef CONFIG_ACPI_SLEEP
/*
* Reserve low memory region for sleep support.
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 821e970..efd9109 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -147,13 +147,25 @@ void smp_invalidate_interrupt(struct pt_regs *regs)
* BUG();
*/
- if (f->flush_mm == percpu_read(cpu_tlbstate.active_mm)) {
- if (percpu_read(cpu_tlbstate.state) == TLBSTATE_OK) {
+ if (f->flush_mm == NULL ||
+ f->flush_mm == percpu_read(cpu_tlbstate.active_mm)) {
+ int tlbstate = percpu_read(cpu_tlbstate.state);
+
+ /*
+ * flush_mm == NULL means flush everything, including
+ * global tlbs, which will only happen when flushing
+ * kernel mappings.
+ */
+ if (f->flush_mm == NULL)
+ __flush_tlb_all();
+ else if (tlbstate == TLBSTATE_OK) {
if (f->flush_va == TLB_FLUSH_ALL)
local_flush_tlb();
else
__flush_tlb_one(f->flush_va);
- } else
+ }
+
+ if (tlbstate == TLBSTATE_LAZY)
leave_mm(cpu);
}
out:
@@ -217,16 +229,13 @@ void native_flush_tlb_others(const struct cpumask *cpumask,
flush_tlb_others_ipi(cpumask, mm, va);
}
-static int __cpuinit init_smp_flush(void)
+void __init init_smp_flush(void)
{
int i;
for (i = 0; i < ARRAY_SIZE(flush_state); i++)
spin_lock_init(&flush_state[i].tlbstate_lock);
-
- return 0;
}
-core_initcall(init_smp_flush);
void flush_tlb_current_task(void)
{
@@ -275,16 +284,16 @@ void flush_tlb_page(struct vm_area_struct *vma, unsigned long va)
preempt_enable();
}
-static void do_flush_tlb_all(void *info)
+void flush_tlb_all(void)
{
- unsigned long cpu = smp_processor_id();
+ /* flush_tlb_others expects preempt to be disabled */
+ get_cpu();
+
+ flush_tlb_others(cpu_online_mask, NULL, TLB_FLUSH_ALL);
__flush_tlb_all();
if (percpu_read(cpu_tlbstate.state) == TLBSTATE_LAZY)
- leave_mm(cpu);
-}
+ leave_mm(smp_processor_id());
-void flush_tlb_all(void)
-{
- on_each_cpu(do_flush_tlb_all, NULL, 1);
+ put_cpu();
}
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 760e3a5..42aa664 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -1284,6 +1284,13 @@ static void xen_flush_tlb_single(unsigned long addr)
preempt_enable();
}
+/*
+ * Flush tlb on other cpus. Xen can do this via a single hypercall
+ * rather than explicit IPIs, which has the nice property of avoiding
+ * any cpus which don't actually have dirty tlbs. Unfortunately it
+ * doesn't give us an opportunity to kick out cpus which are in lazy
+ * tlb state, so we may end up reflushing some cpus unnecessarily.
+ */
static void xen_flush_tlb_others(const struct cpumask *cpus,
struct mm_struct *mm, unsigned long va)
{
--
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