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Re: [Qemu-devel] [Xen-devel] [v2][PATCH 6/8] xen, gfx passthrough: suppo
From: |
Chen, Tiejun |
Subject: |
Re: [Qemu-devel] [Xen-devel] [v2][PATCH 6/8] xen, gfx passthrough: support Intel IGD passthrough with VT-D |
Date: |
Tue, 20 May 2014 05:13:45 +0000 |
> -----Original Message-----
> From: Konrad Rzeszutek Wilk [mailto:address@hidden
> Sent: Monday, May 19, 2014 9:34 PM
> To: Zhang, Yang Z
> Cc: Chen, Tiejun; address@hidden; address@hidden;
> address@hidden; address@hidden; address@hidden;
> address@hidden; address@hidden; Kay, Allen M;
> address@hidden; address@hidden;
> address@hidden
> Subject: Re: [Xen-devel] [v2][PATCH 6/8] xen, gfx passthrough: support Intel
> IGD passthrough with VT-D
>
> On Mon, May 19, 2014 at 12:58:50AM +0000, Zhang, Yang Z wrote:
> > Konrad Rzeszutek Wilk wrote on 2014-05-16:
> > > On Fri, May 16, 2014 at 06:53:42PM +0800, Tiejun Chen wrote:
> > > > Some registers of Intel IGD are mapped in host bridge, so it needs
> > > > to passthrough these registers of physical host bridge to guest
> > > > because emulated host bridge in guest doesn't have these mappings.
> >
> > Thanks for your review for the whole series patch.
>
> Sure thing!
>
> .. snip..
> > > > +write_default:
> > > > + pci_default_write_config(pci_dev, config_addr, val, len);
> > >
> > >
> > > and we just allow it through. But what happens if the guest decides
> > > to change the BAR sizes? Or fiddle with the GTT?
> > >
> > > Ouch. That really looks dangerous - or maybe I am too paranoid?
> > >
> >
> > I do not quite understand your concern. We only pass through PAVPC to
> physical host bridge. The others are handled by current logic. We don't change
> any of it. So what problem will be exposed by this patch?
>
> Ah, I assumed that pci_default_write_config would be writting everything
> without any checks. But it looks to be doing the right thing and just sets the
> emulated values.
>
> Could we just add comment saying that it writes to the emulated values? That
> way it won't trip folks.
diff --git a/hw/xen/xen_pt_graphics.c b/hw/xen/xen_pt_graphics.c
index 1342f4f..5e5e3d5 100644
--- a/hw/xen/xen_pt_graphics.c
+++ b/hw/xen/xen_pt_graphics.c
@@ -367,6 +367,7 @@ void igd_pci_write(PCIDevice *pci_dev, uint32_t config_addr,
case 0x58: /* PAVPC Offset */
break;
default:
+ /* Just sets the emulated values. */
goto write_default;
}
@@ -427,6 +428,7 @@ uint32_t igd_pci_read(PCIDevice *pci_dev, uint32_t
config_addr, int len)
case 0xa8: /* SNB: base of GTT stolen memory */
break;
default:
+ /* Just gets the emulated values. */
goto read_default;
}
Thanks
Tiejun
[Qemu-devel] [v2][PATCH 5/8] xen, gfx passthrough: create intel isa bridge, Tiejun Chen, 2014/05/16
[Qemu-devel] [v2][PATCH 6/8] xen, gfx passthrough: support Intel IGD passthrough with VT-D, Tiejun Chen, 2014/05/16
- Re: [Qemu-devel] [Xen-devel] [v2][PATCH 6/8] xen, gfx passthrough: support Intel IGD passthrough with VT-D, Konrad Rzeszutek Wilk, 2014/05/16
- Re: [Qemu-devel] [Xen-devel] [v2][PATCH 6/8] xen, gfx passthrough: support Intel IGD passthrough with VT-D, Zhang, Yang Z, 2014/05/18
- Re: [Qemu-devel] [Xen-devel] [v2][PATCH 6/8] xen, gfx passthrough: support Intel IGD passthrough with VT-D, Konrad Rzeszutek Wilk, 2014/05/19
- Re: [Qemu-devel] [Xen-devel] [v2][PATCH 6/8] xen, gfx passthrough: support Intel IGD passthrough with VT-D,
Chen, Tiejun <=
- Re: [Qemu-devel] [Xen-devel] [v2][PATCH 6/8] xen, gfx passthrough: support Intel IGD passthrough with VT-D, Konrad Rzeszutek Wilk, 2014/05/20
Re: [Qemu-devel] [Xen-devel] [v2][PATCH 6/8] xen, gfx passthrough: support Intel IGD passthrough with VT-D, Chen, Tiejun, 2014/05/19
[Qemu-devel] [v2][PATCH 8/8] xen, gfx passthrough: add opregion mapping, Tiejun Chen, 2014/05/16
- Re: [Qemu-devel] [v2][PATCH 8/8] xen, gfx passthrough: add opregion mapping, Stefano Stabellini, 2014/05/19
- Re: [Qemu-devel] [v2][PATCH 8/8] xen, gfx passthrough: add opregion mapping, Chen, Tiejun, 2014/05/20
- Re: [Qemu-devel] [v2][PATCH 8/8] xen, gfx passthrough: add opregion mapping, Stefano Stabellini, 2014/05/20
- Re: [Qemu-devel] [v2][PATCH 8/8] xen, gfx passthrough: add opregion mapping, Chen, Tiejun, 2014/05/20
[Qemu-devel] [v2][PATCH 7/8] xen, gfx passthrough: create host bridge to passthrough, Tiejun Chen, 2014/05/16