From mboxrd@z Thu Jan  1 00:00:00 1970
From: Anthony Liguori <anthony@codemonkey.ws>
Subject: Re: Single memory slot
Date: Thu, 15 Oct 2009 13:51:07 -0500
Message-ID: <4AD76F1B.3040607@codemonkey.ws>
References: <4AD6D037.3060301@redhat.com>
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Cc: Marcelo Tosatti <mtosatti@redhat.com>,
	kvm-devel <kvm@vger.kernel.org>
To: Avi Kivity <avi@redhat.com>
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Avi Kivity wrote:
> One way to improve the gfn_to_pfn() memslot search is to register just 
> one slot.  This can only work on 64-bit, since even the smallest 
> guests need 4GB of physical address space.  Apart from speeding up 
> gfn_to_page(), it would also speed up mmio which must iterate over all 
> slots, so a lookup cache cannot help.
>
> This would require quite a bunch of changes:
> - modify gfn_to_pfn() to fail gracefully if the page is in the slot 
> but unmapped (hole handling)
> - modify qemu to reserve the guest physical address space

It could potentially speed up qemu quite a lot too as we would return to 
a model where host va == fixed address + guest pa.  That makes things 
like stl_phys/ldl_phys trivial.

Regards,

Anthony Liguori