From: Ram Pai <linuxram@us.ibm.com>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: andmike@us.ibm.com, mst@redhat.com, aik@ozlabs.ru,
mdroth@linux.vnet.ibm.com, linux-kernel@vger.kernel.org,
ram.n.pai@gmail.com, cai@lca.pw, tglx@linutronix.de,
sukadev@linux.vnet.ibm.com, linuxppc-dev@lists.ozlabs.org,
hch@lst.de, bauerman@linux.ibm.com, david@gibson.dropbear.id.au
Subject: RE: [RFC v1 2/2] powerpc/pseries/iommu: Use dma_iommu_ops for Secure VMs aswell.
Date: Thu, 7 Nov 2019 21:49:22 -0800 [thread overview]
Message-ID: <20191108054922.GH5201@oc0525413822.ibm.com> (raw)
In-Reply-To: <87k18c56ej.fsf@mpe.ellerman.id.au>
On Thu, Nov 07, 2019 at 09:26:28PM +1100, Michael Ellerman wrote:
> Ram Pai <linuxram@us.ibm.com> writes:
> > This enables IOMMU support for pseries Secure VMs.
>
> Can you give us some more explanation please?
Yes. Will do.
The simple explanation is -- it was a mistake. We should
not have disabled IOMMU ops for secure guests. Though it enabled
us to use virtio devices, with the help of some additional patches to
the virtio subsystem; in hindsight, we should not have disabled IOMMU
ops for secure VMs :-(.
RP
>
> This is basically a revert of commit:
> edea902c1c1e ("powerpc/pseries/iommu: Don't use dma_iommu_ops on secure guests")
>
> But neglects to remove the now unnecessary include of svm.h.
>
> > diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
> > index 07f0847..189717b 100644
> > --- a/arch/powerpc/platforms/pseries/iommu.c
> > +++ b/arch/powerpc/platforms/pseries/iommu.c
> > @@ -1333,15 +1333,7 @@ void iommu_init_early_pSeries(void)
> > of_reconfig_notifier_register(&iommu_reconfig_nb);
> > register_memory_notifier(&iommu_mem_nb);
> >
> > - /*
> > - * Secure guest memory is inacessible to devices so regular DMA isn't
> > - * possible.
> > - *
> > - * In that case keep devices' dma_map_ops as NULL so that the generic
> > - * DMA code path will use SWIOTLB to bounce buffers for DMA.
>
> Please explain what has changed to make this no longer necessary.
>
> cheers
>
> > - */
> > - if (!is_secure_guest())
> > - set_pci_dma_ops(&dma_iommu_ops);
> > + set_pci_dma_ops(&dma_iommu_ops);
> > }
> >
> > static int __init disable_multitce(char *str)
> > --
> > 1.8.3.1
--
Ram Pai
next prev parent reply other threads:[~2019-11-08 5:51 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-04 21:28 [RFC v1 0/2] Enable IOMMU support for pseries Secure VMs Ram Pai
2019-11-04 21:28 ` [RFC v1 1/2] powerpc/pseries/iommu: Share the per-cpu TCE page with the hypervisor Ram Pai
2019-11-04 21:28 ` [RFC v1 2/2] powerpc/pseries/iommu: Use dma_iommu_ops for Secure VMs aswell Ram Pai
2019-11-07 10:26 ` Michael Ellerman
2019-11-08 5:49 ` Ram Pai [this message]
2019-11-06 1:58 ` [RFC v1 1/2] powerpc/pseries/iommu: Share the per-cpu TCE page with the hypervisor Alexey Kardashevskiy
2019-11-06 17:01 ` Ram Pai
2019-11-07 5:58 ` Alexey Kardashevskiy
2019-11-07 10:29 ` Michael Ellerman
2019-11-08 6:05 ` Ram Pai
2019-11-06 1:59 ` [RFC v1 0/2] Enable IOMMU support for pseries Secure VMs Alexey Kardashevskiy
2019-11-06 16:46 ` Ram Pai
2019-11-06 18:06 ` Michael S. Tsirkin
2019-11-06 18:52 ` Michael Roth
2019-11-06 22:22 ` Ram Pai
2019-11-07 6:01 ` Alexey Kardashevskiy
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20191108054922.GH5201@oc0525413822.ibm.com \
--to=linuxram@us.ibm.com \
--cc=aik@ozlabs.ru \
--cc=andmike@us.ibm.com \
--cc=bauerman@linux.ibm.com \
--cc=cai@lca.pw \
--cc=david@gibson.dropbear.id.au \
--cc=hch@lst.de \
--cc=linux-kernel@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=mdroth@linux.vnet.ibm.com \
--cc=mpe@ellerman.id.au \
--cc=mst@redhat.com \
--cc=ram.n.pai@gmail.com \
--cc=sukadev@linux.vnet.ibm.com \
--cc=tglx@linutronix.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).