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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Tue, 29 Jan 2019 17:43:07 -0000 Received: from b01ledav006.gho.pok.ibm.com (b01ledav006.gho.pok.ibm.com [9.57.199.111]) by b01cxnp23033.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x0THh6cR24903760 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Tue, 29 Jan 2019 17:43:06 GMT Received: from b01ledav006.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 5FF15AC062; Tue, 29 Jan 2019 17:43:06 +0000 (GMT) Received: from b01ledav006.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 419DFAC059; Tue, 29 Jan 2019 17:42:55 +0000 (GMT) Received: from morokweng.localdomain (unknown [9.85.217.24]) by b01ledav006.gho.pok.ibm.com (Postfix) with ESMTPS; Tue, 29 Jan 2019 17:42:53 +0000 (GMT) References: <87zhrj8kcp.fsf@morokweng.localdomain> User-agent: mu4e 1.0; emacs 26.1 From: Thiago Jung Bauermann To: virtualization@lists.linux-foundation.org Subject: Re: [RFC PATCH] virtio_ring: Use DMA API if guest memory is encrypted In-reply-to: <87zhrj8kcp.fsf@morokweng.localdomain> Date: Tue, 29 Jan 2019 15:42:44 -0200 MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-GCONF: 00 x-cbid: 19012917-0040-0000-0000-000004B932F7 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00010500; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000277; SDB=6.01153551; UDB=6.00593882; IPR=6.00933917; MB=3.00025343; MTD=3.00000008; XFM=3.00000015; UTC=2019-01-29 17:43:09 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19012917-0041-0000-0000-000008C447A6 Message-Id: <87womn8inf.fsf@morokweng.localdomain> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:, , definitions=2019-01-29_13:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=1 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1901290131 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Michael S . Tsirkin" , Jason Wang , Alexey Kardashevskiy , Ram Pai , linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, linuxppc-dev@lists.ozlabs.org, Christoph Hellwig , David Gibson Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Fixing address of powerpc mailing list. Thiago Jung Bauermann writes: > Hello, > > With Christoph's rework of the DMA API that recently landed, the patch > below is the only change needed in virtio to make it work in a POWER > secure guest under the ultravisor. > > The other change we need (making sure the device's dma_map_ops is NULL > so that the dma-direct/swiotlb code is used) can be made in > powerpc-specific code. > > Of course, I also have patches (soon to be posted as RFC) which hook up > to the powerpc secure guest support code. > > What do you think? > > From d0629a36a75c678b4a72b853f8f7f8c17eedd6b3 Mon Sep 17 00:00:00 2001 > From: Thiago Jung Bauermann > Date: Thu, 24 Jan 2019 22:08:02 -0200 > Subject: [RFC PATCH] virtio_ring: Use DMA API if guest memory is encrypted > > The host can't access the guest memory when it's encrypted, so using > regular memory pages for the ring isn't an option. Go through the DMA API. > > Signed-off-by: Thiago Jung Bauermann > --- > drivers/virtio/virtio_ring.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > index cd7e755484e3..321a27075380 100644 > --- a/drivers/virtio/virtio_ring.c > +++ b/drivers/virtio/virtio_ring.c > @@ -259,8 +259,11 @@ static bool vring_use_dma_api(struct virtio_device *vdev) > * not work without an even larger kludge. Instead, enable > * the DMA API if we're a Xen guest, which at least allows > * all of the sensible Xen configurations to work correctly. > + * > + * Also, if guest memory is encrypted the host can't access > + * it directly. In this case, we'll need to use the DMA API. > */ > - if (xen_domain()) > + if (xen_domain() || sev_active()) > return true; > > return false; -- Thiago Jung Bauermann IBM Linux Technology Center