Re: [Qemu-devel] Default for phys-addr-bits? (was Re: [PATCH 4/5] x86: Allow physical address bits to be set)

[Michael S. Tsirkin]

On Wed, Jun 22, 2016 at 04:24:14PM +0200, Andrea Arcangeli wrote:
> > cause malfunctioning, only crashes (and as Gerd said, if you cross your
> > fingers and hope the guest doesn't put anything so high in memory,
> > chances are you'll succeed), and this makes it "safer".  I'm not sure
> > which one is more likely to happen.
> 
> But the crash with guest phys bits > host phys bits is material, linux
> will definitely crash in such condition.

Why would it? Most GPA addresses are not guest controllable.
Don't give guest addresses that host can't access, you will not get
a crash.

The only exception I know of is PCI BARs but we can limit
these to a safe addressable range using _CRS method in ACPI.

Could you explain please?

-- 
MST