[PATCH 6/8] x86: use flush_tlb_others to implement flush_tlb_all

Jeremy Fitzhardinge
2009-05-08T00:33:35Z

From: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

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.

(Nothing similar is required for xen_flush_tlb_others, as we don't use
global mappings in a guest-visible way under Xen.)

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
---
arch/x86/mm/tlb.c | 29 ++++++++++++++++++-----------
arch/x86/xen/mmu.c | 7 +++++++
2 files changed, 25 insertions(+), 11 deletions(-)

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 821e970..e69bdad 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:
@@ -275,16 +287,11 @@ 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(cpu_online_mask, NULL, TLB_FLUSH_ALL);

__flush_tlb_all();
if (percpu_read(cpu_tlbstate.state) == TLBSTATE_LAZY)
- leave_mm(cpu);
-}
-
-void flush_tlb_all(void)
-{
- on_each_cpu(do_flush_tlb_all, NULL, 1);
+ leave_mm(smp_processor_id());
}
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 5af62d8..0e13477 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)
{
--
1.6.0.6