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From: Alexander Graf <agraf-l3A5Bk7waGM@public.gmane.org>
To: kvm-ppc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Cc: kvm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	benh-XVmvHMARGAS8U2dJNN8I7kB+6BGkLq7r@public.gmane.org
Subject: [PATCH] Use Little Endian for Dirty Bitmap
Date: Mon, 27 Jul 2009 12:38:54 +0200	[thread overview]
Message-ID: <1248691134-54120-1-git-send-email-agraf@suse.de> (raw)

We currently use host endian long types to store information
in the dirty bitmap.

This works reasonably well on Little Endian targets, because the
u32 after the first contains the next 32 bits. On Big Endian this
breaks completely though, forcing us to be inventive here.

So Ben suggested to always use Little Endian, which looks reasonable.

We only have dirty bitmap implemented in Little Endian targets so far
and since PowerPC would be the first Big Endian platform, we can just
as well switch to Little Endian always with little effort without
breaking existing targets.

Signed-off-by: Alexander Graf <agraf-l3A5Bk7waGM@public.gmane.org>
---
 virt/kvm/kvm_main.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 17d8688..3482ad1 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -48,6 +48,7 @@
 #include <asm/io.h>
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
+#include <asm-generic/bitops/le.h>
 
 #ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
 #include "coalesced_mmio.h"
@@ -1656,8 +1657,8 @@ void mark_page_dirty(struct kvm *kvm, gfn_t gfn)
 		unsigned long rel_gfn = gfn - memslot->base_gfn;
 
 		/* avoid RMW */
-		if (!test_bit(rel_gfn, memslot->dirty_bitmap))
-			set_bit(rel_gfn, memslot->dirty_bitmap);
+		if (!generic_test_le_bit(rel_gfn, memslot->dirty_bitmap))
+			generic___set_le_bit(rel_gfn, memslot->dirty_bitmap);
 	}
 }
 
-- 
1.6.0.2

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WARNING: multiple messages have this Message-ID (diff)
From: Alexander Graf <agraf@suse.de>
To: kvm-ppc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Cc: kvm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	benh-XVmvHMARGAS8U2dJNN8I7kB+6BGkLq7r@public.gmane.org
Subject: [PATCH] Use Little Endian for Dirty Bitmap
Date: Mon, 27 Jul 2009 10:38:54 +0000	[thread overview]
Message-ID: <1248691134-54120-1-git-send-email-agraf@suse.de> (raw)

We currently use host endian long types to store information
in the dirty bitmap.

This works reasonably well on Little Endian targets, because the
u32 after the first contains the next 32 bits. On Big Endian this
breaks completely though, forcing us to be inventive here.

So Ben suggested to always use Little Endian, which looks reasonable.

We only have dirty bitmap implemented in Little Endian targets so far
and since PowerPC would be the first Big Endian platform, we can just
as well switch to Little Endian always with little effort without
breaking existing targets.

Signed-off-by: Alexander Graf <agraf@suse.de>
---
 virt/kvm/kvm_main.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 17d8688..3482ad1 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -48,6 +48,7 @@
 #include <asm/io.h>
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
+#include <asm-generic/bitops/le.h>
 
 #ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
 #include "coalesced_mmio.h"
@@ -1656,8 +1657,8 @@ void mark_page_dirty(struct kvm *kvm, gfn_t gfn)
 		unsigned long rel_gfn = gfn - memslot->base_gfn;
 
 		/* avoid RMW */
-		if (!test_bit(rel_gfn, memslot->dirty_bitmap))
-			set_bit(rel_gfn, memslot->dirty_bitmap);
+		if (!generic_test_le_bit(rel_gfn, memslot->dirty_bitmap))
+			generic___set_le_bit(rel_gfn, memslot->dirty_bitmap);
 	}
 }
 
-- 
1.6.0.2


             reply	other threads:[~2009-07-27 10:38 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-07-27 10:38 Alexander Graf [this message]
2009-07-27 10:38 ` [PATCH] Use Little Endian for Dirty Bitmap Alexander Graf
     [not found] ` <1248691134-54120-1-git-send-email-agraf-l3A5Bk7waGM@public.gmane.org>
2009-09-26 14:35   ` Alexander Graf
2009-09-26 14:35     ` Alexander Graf
2009-09-29  0:08 ` Hollis Blanchard
2009-09-29  0:08   ` Hollis Blanchard
     [not found]   ` <1254182880.15622.157.camel-yDUrRDS8jBVhsM67afOH+sxtgHpCUUYS@public.gmane.org>
2009-09-29  0:10     ` Alexander Graf
2009-09-29  0:10       ` Alexander Graf

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