linux-kernel - Re: [RFC V2] virtio: Add platform specific DMA API translation for virito devices

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Tue, 5 Jun 2018 11:52:36 +1000
From:   David Gibson <david@...son.dropbear.id.au>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc:     "Michael S. Tsirkin" <mst@...hat.com>,
        Anshuman Khandual <khandual@...ux.vnet.ibm.com>,
        virtualization@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        aik@...abs.ru, robh@...nel.org, joe@...ches.com,
        elfring@...rs.sourceforge.net, jasowang@...hat.com,
        mpe@...erman.id.au, hch@...radead.org
Subject: Re: [RFC V2] virtio: Add platform specific DMA API translation for
 virito devices

On Mon, Jun 04, 2018 at 07:48:54PM +1000, Benjamin Herrenschmidt wrote:
> On Mon, 2018-06-04 at 18:57 +1000, David Gibson wrote:
> > 
> > > - First qemu doesn't know that the guest will switch to "secure mode"
> > > in advance. There is no difference between a normal and a secure
> > > partition until the partition does the magic UV call to "enter secure
> > > mode" and qemu doesn't see any of it. So who can set the flag here ?
> > 
> > This seems weird to me.  As a rule HV calls should go through qemu -
> > or be allowed to go directly to KVM *by* qemu.
> 
> It's not an HV call, it's a UV call, qemu won't see it, qemu isn't
> trusted. Now the UV *will* reflect that to the HV via some synthetized
> HV calls, and we *could* have those do a pass by qemu, however, so far,
> our entire design doesn't rely on *any* qemu knowledge whatsoever and
> it would be sad to add it just for that purpose.
> 
> Additionally, this is rather orthogonal, see my other email, the
> problem we are trying to solve is *not* a qemu problem and it doesn't
> make sense to leak that into qemu.
> 
> >   We generally reserve
> > the latter for hot path things.  Since this isn't a hot path, having
> > the call handled directly by the kernel seems wrong.
> >
> > Unless a "UV call" is something different I don't know about.
> 
> Yes, a UV call goes to the Ultravisor, not the Hypervisor. The
> Hypervisor isn't trusted.

Ah, right.  Is that implemented in the host kernel, or in something
further above?

-- 
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

Download attachment "signature.asc" of type "application/pgp-signature" (834 bytes)