Linux 3.6.7

[thirdparty/kernel/stable-queue.git] / releases / 3.6.7 / xen-mmu-use-xen-specific-tlb-flush-instead-of-the-generic-one.patch

diff --git a/releases/3.6.7/xen-mmu-use-xen-specific-tlb-flush-instead-of-the-generic-one.patch b/releases/3.6.7/xen-mmu-use-xen-specific-tlb-flush-instead-of-the-generic-one.patch
new file mode 100644 (file)
index 0000000..ee536db
--- /dev/null
+++ b/releases/3.6.7/xen-mmu-use-xen-specific-tlb-flush-instead-of-the-generic-one.patch
@@ -0,0 +1,88 @@
+From 95a7d76897c1e7243d4137037c66d15cbf2cce76 Mon Sep 17 00:00:00 2001
+From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
+Date: Wed, 31 Oct 2012 12:38:31 -0400
+Subject: xen/mmu: Use Xen specific TLB flush instead of the generic one.
+
+From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
+
+commit 95a7d76897c1e7243d4137037c66d15cbf2cce76 upstream.
+
+As Mukesh explained it, the MMUEXT_TLB_FLUSH_ALL allows the
+hypervisor to do a TLB flush on all active vCPUs. If instead
+we were using the generic one (which ends up being xen_flush_tlb)
+we end up making the MMUEXT_TLB_FLUSH_LOCAL hypercall. But
+before we make that hypercall the kernel will IPI all of the
+vCPUs (even those that were asleep from the hypervisor
+perspective). The end result is that we needlessly wake them
+up and do a TLB flush when we can just let the hypervisor
+do it correctly.
+
+This patch gives around 50% speed improvement when migrating
+idle guest's from one host to another.
+
+Oracle-bug: 14630170
+
+Tested-by:  Jingjie Jiang <jingjie.jiang@oracle.com>
+Suggested-by:  Mukesh Rathor <mukesh.rathor@oracle.com>
+Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ arch/x86/xen/mmu.c         |   21 ++++++++++++++++++++-
+ include/trace/events/xen.h |    8 ++++++++
+ 2 files changed, 28 insertions(+), 1 deletion(-)
+
+--- a/arch/x86/xen/mmu.c
++++ b/arch/x86/xen/mmu.c
+@@ -1215,6 +1215,25 @@ unsigned long xen_read_cr2_direct(void)
+       return this_cpu_read(xen_vcpu_info.arch.cr2);
+ }
+ 
++void xen_flush_tlb_all(void)
++{
++      struct mmuext_op *op;
++      struct multicall_space mcs;
++
++      trace_xen_mmu_flush_tlb_all(0);
++
++      preempt_disable();
++
++      mcs = xen_mc_entry(sizeof(*op));
++
++      op = mcs.args;
++      op->cmd = MMUEXT_TLB_FLUSH_ALL;
++      MULTI_mmuext_op(mcs.mc, op, 1, NULL, DOMID_SELF);
++
++      xen_mc_issue(PARAVIRT_LAZY_MMU);
++
++      preempt_enable();
++}
+ static void xen_flush_tlb(void)
+ {
+       struct mmuext_op *op;
+@@ -2366,7 +2385,7 @@ int xen_remap_domain_mfn_range(struct vm
+       err = 0;
+ out:
+ 
+-      flush_tlb_all();
++      xen_flush_tlb_all();
+ 
+       return err;
+ }
+--- a/include/trace/events/xen.h
++++ b/include/trace/events/xen.h
+@@ -377,6 +377,14 @@ DECLARE_EVENT_CLASS(xen_mmu_pgd,
+ DEFINE_XEN_MMU_PGD_EVENT(xen_mmu_pgd_pin);
+ DEFINE_XEN_MMU_PGD_EVENT(xen_mmu_pgd_unpin);
+ 
++TRACE_EVENT(xen_mmu_flush_tlb_all,
++          TP_PROTO(int x),
++          TP_ARGS(x),
++          TP_STRUCT__entry(__array(char, x, 0)),
++          TP_fast_assign((void)x),
++          TP_printk("%s", "")
++      );
++
+ TRACE_EVENT(xen_mmu_flush_tlb,
+           TP_PROTO(int x),
+           TP_ARGS(x),