[PATCH 08/19] KVM: PPC: Book3S HV: add a VC_BASE control to the XIVE native device

[David Gibson]

On Wed, Jan 23, 2019 at 05:56:26PM +0100, Cédric Le Goater wrote:
> On 1/22/19 6:14 AM, Paul Mackerras wrote:
> > On Mon, Jan 07, 2019 at 07:43:20PM +0100, Cédric Le Goater wrote:
> >> The ESB MMIO region controls the interrupt sources of the guest. QEMU
> >> will query an fd (GET_ESB_FD ioctl) and map this region at a specific
> >> address for the guest to use. The guest will obtain this information
> >> using the H_INT_GET_SOURCE_INFO hcall. To inform KVM of the address
> >> setting used by QEMU, add a VC_BASE control to the KVM XIVE device
> > 
> > This needs a little more explanation.  I *think* the only way this
> > gets used is that it gets returned to the guest by the new
> > hypercalls.  If that is indeed the case it would be useful to mention
> > that in the patch description, because otherwise taking a value that
> > userspace provides and which looks like it is an address, and not
> > doing any validation on it, looks a bit scary.
> 
> I think we have solved this problem in another email thread. 
> 
> The H_INT_GET_SOURCE_INFO hcall does not need to be implemented in KVM
> as all the source information should already be available in QEMU. In
> that case, there is no need to inform KVM of where the ESB pages are 
> mapped in the guest address space. So we don't need that extra control
> on the KVM device. This is good news.

Ah, good to hear.  I thought this looked strange.


-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson
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