From mboxrd@z Thu Jan  1 00:00:00 1970
From: Marcelo Tosatti <mtosatti@redhat.com>
Subject: Re: [patch uq/master 2/2] kvm-all.c: define smp_wmb and use it for
 coalesced mmio
Date: Mon, 22 Feb 2010 11:45:41 -0300
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Cc: kvm@vger.kernel.org, qemu-devel@nongnu.org,
	"Michael S. Tsirkin" <mst@redhat.com>
To: Avi Kivity <avi@redhat.com>
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On Mon, Feb 22, 2010 at 04:23:32PM +0200, Avi Kivity wrote:
> On 02/22/2010 03:59 PM, Marcelo Tosatti wrote:
> >Cc: "Michael S. Tsirkin"<mst@redhat.com>
> >Signed-off-by: Marcelo Tosatti<mtosatti@redhat.com>
> >
> >Index: qemu/kvm-all.c
> >===================================================================
> >--- qemu.orig/kvm-all.c
> >+++ qemu/kvm-all.c
> >@@ -718,6 +718,9 @@ static int kvm_handle_io(uint16_t port,
> >      return 1;
> >  }
> >
> >+/* FIXME: arch dependant, x86 version */
> >+#define smp_wmb()   asm volatile("" ::: "memory")
> >+
> 
> sfence?  

There is no need (for this case). Older read cannot be reordered with
write, writes are not reordered with other writes, writes by a single
processor are observed in the same order by all processors.

> what about other arches?

They need to be fixed? PPC needs an instruction apparently.

Is there any objection to including this patch?