Re: [Qemu-devel] [PATCH] kvm: Fix dirty tracking with large kernel page size

[David Gibson <david@gibson.dropbear.id.au>]

On Mon, Mar 19, 2012 at 11:52:49AM +0100, Andreas Färber wrote:
> Am 19.03.2012 05:57, schrieb David Gibson:
> > If the kernel page size is larger than TARGET_PAGE_SIZE, which
> > happens for example on ppc64 with kernels compiled for 64K pages,
> > the dirty tracking doesn't work.
> > 
> > Cc: Avi Kivity <avi@redhat.com>
> > Cc: Marcelo Tossatti <mtosatti@redhat.com>
> > 
> > Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> > Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> > ---
> >  kvm-all.c |    8 +++++---
> >  1 files changed, 5 insertions(+), 3 deletions(-)
> > 
> > diff --git a/kvm-all.c b/kvm-all.c
> > index ba2cee1..47adc97 100644
> > --- a/kvm-all.c
> > +++ b/kvm-all.c
> > @@ -350,10 +350,11 @@ static int kvm_set_migration_log(int enable)
> >  static int kvm_get_dirty_pages_log_range(MemoryRegionSection *section,
> >                                           unsigned long *bitmap)
> >  {
> > -    unsigned int i, j;
> > +  unsigned int i, j;
> 
> Unintentional change?

Gah, yes, oops.  Corrected version below.

>From 55bd7c4811415c3b1a4825c4907f56117243836b Mon Sep 17 00:00:00 2001
From: Ben Herrenschmidt <benh@kernel.crashing.org>
Date: Tue, 20 Mar 2012 11:22:16 +1100
Subject: [PATCH] kvm: Fix dirty tracking with large kernel page size

If the kernel page size is larger than TARGET_PAGE_SIZE, which
happens for example on ppc64 with kernels compiled for 64K pages,
the dirty tracking doesn't work.

Cc: Avi Kivity <avi@redhat.com>
Cc: Marcelo Tossatti <mtosatti@redhat.com>

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 kvm-all.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/kvm-all.c b/kvm-all.c
index ba2cee1..7e44429 100644
--- a/kvm-all.c
+++ b/kvm-all.c
@@ -354,6 +354,7 @@ static int kvm_get_dirty_pages_log_range(MemoryRegionSection *section,
     unsigned long page_number, c;
     target_phys_addr_t addr, addr1;
     unsigned int len = ((section->size / TARGET_PAGE_SIZE) + HOST_LONG_BITS - 1) / HOST_LONG_BITS;
+    unsigned long hpratio = getpagesize() / TARGET_PAGE_SIZE;
 
     /*
      * bitmap-traveling is faster than memory-traveling (for addr...)
@@ -365,10 +366,11 @@ static int kvm_get_dirty_pages_log_range(MemoryRegionSection *section,
             do {
                 j = ffsl(c) - 1;
                 c &= ~(1ul << j);
-                page_number = i * HOST_LONG_BITS + j;
+                page_number = (i * HOST_LONG_BITS + j) * hpratio;
                 addr1 = page_number * TARGET_PAGE_SIZE;
                 addr = section->offset_within_region + addr1;
-                memory_region_set_dirty(section->mr, addr, TARGET_PAGE_SIZE);
+                memory_region_set_dirty(section->mr, addr,
+                                        TARGET_PAGE_SIZE * hpratio);
             } while (c != 0);
         }
     }
-- 
1.7.9.1



-- 
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