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From: "Michael S. Tsirkin" <mst-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
To: Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>
Cc: Jean-Philippe Brucker
	<jean-philippe.brucker-5wv7dgnIgG8@public.gmane.org>,
	Benjamin Herrenschmidt
	<benh-XVmvHMARGAS8U2dJNN8I7kB+6BGkLq7r@public.gmane.org>,
	Jason Wang <jasowang-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	Alexey Kardashevskiy
	<aik-tEXmvtCZX7AybS5Ee8rs3A@public.gmane.org>,
	Ram Pai <linuxram-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	virtualization-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
	Paul Mackerras <paulus-mnsaURCQ41sdnm+yROfE0A@public.gmane.org>,
	iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
	linuxppc-dev-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org,
	David Gibson
	<david-xT8FGy+AXnRB3Ne2BGzF6laj5H9X9Tb+@public.gmane.org>
Subject: Re: [RFC PATCH] virtio_ring: Use DMA API if guest memory is encrypted
Date: Tue, 5 Feb 2019 11:13:39 -0500	[thread overview]
Message-ID: <20190205111128-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20190205072407.GA4311-jcswGhMUV9g@public.gmane.org>

On Tue, Feb 05, 2019 at 08:24:07AM +0100, Christoph Hellwig wrote:
> On Mon, Feb 04, 2019 at 04:38:21PM -0500, Michael S. Tsirkin wrote:
> > It was designed to make, when set, as many guests as we can work
> > correctly, and it seems to be successful in doing exactly that.
> > 
> > Unfortunately there could be legacy guests that do work correctly but
> > become slow. Whether trying to somehow work around that
> > can paint us into a corner where things again don't
> > work for some people is a question worth discussing.
> 
> The other problem is that some qemu machines just throw passthrough
> devices and virtio devices on the same virtual PCI(e) bus, and have a
> common IOMMU setup for the whole bus / root port / domain.  I think
> this is completely bogus, but unfortunately it is out in the field.
> 
> Given that power is one of these examples I suspect that is what
> Thiago referes to.  But in this case the answer can't be that we
> pile on hack ontop of another, but instead introduce a new qemu
> machine that separates these clearly, and make that mandatory for
> the secure guest support.

That could we one approach, assuming one exists that guests
already support.

-- 
MST

  parent reply	other threads:[~2019-02-05 16:13 UTC|newest]

Thread overview: 64+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-29 17:08 [RFC PATCH] virtio_ring: Use DMA API if guest memory is encrypted Thiago Jung Bauermann
2019-01-29 17:42 ` Thiago Jung Bauermann
2019-01-29 19:02   ` Michael S. Tsirkin
2019-01-30  2:24     ` Jason Wang
2019-01-30  2:36       ` Michael S. Tsirkin
2019-01-30  3:05         ` Jason Wang
2019-01-30  3:26           ` Michael S. Tsirkin
2019-01-30  7:44         ` Christoph Hellwig
2019-02-04 18:15           ` Thiago Jung Bauermann
2019-02-04 21:38             ` Michael S. Tsirkin
2019-02-05  7:24               ` Christoph Hellwig
     [not found]                 ` <20190205072407.GA4311-jcswGhMUV9g@public.gmane.org>
2019-02-05 16:13                   ` Michael S. Tsirkin [this message]
2019-03-26 16:53           ` Michael S. Tsirkin
2019-02-04 18:14     ` Thiago Jung Bauermann
2019-02-04 20:23       ` Michael S. Tsirkin
2019-03-20 16:13         ` Thiago Jung Bauermann
2019-03-20 21:17           ` Michael S. Tsirkin
2019-03-22  0:05             ` Thiago Jung Bauermann
2019-03-23 21:01               ` Michael S. Tsirkin
2019-03-25  0:57                 ` David Gibson
2019-04-17 21:42                   ` Thiago Jung Bauermann
2019-04-17 21:42                     ` Thiago Jung Bauermann
     [not found]                 ` <20190323165456-mutt-send-email-mst-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2019-04-17 21:42                   ` Thiago Jung Bauermann
2019-04-17 21:42                     ` Thiago Jung Bauermann
2019-04-19 23:09                     ` Michael S. Tsirkin
2019-04-19 23:09                       ` Michael S. Tsirkin
2019-04-25  1:01                       ` Thiago Jung Bauermann
2019-04-25  1:01                         ` Thiago Jung Bauermann
     [not found]                         ` <875zr228zf.fsf-wxVGo8vDogbJvNEK5ZsId7p2dZbC/Bob@public.gmane.org>
2019-04-25  1:18                           ` Michael S. Tsirkin
2019-04-25  1:18                             ` Michael S. Tsirkin
2019-04-26 23:56                             ` Thiago Jung Bauermann
2019-04-26 23:56                               ` Thiago Jung Bauermann
2019-05-20 13:08                               ` Michael S. Tsirkin
2019-05-20 13:16                     ` Michael S. Tsirkin
2019-06-04  1:13                       ` Thiago Jung Bauermann
2019-06-04  1:42                         ` Michael S. Tsirkin
2019-06-28  1:58                           ` Thiago Jung Bauermann
2019-07-01 14:17                             ` Michael S. Tsirkin
2019-07-14  5:51                               ` Thiago Jung Bauermann
2019-07-15 14:35                                 ` Michael S. Tsirkin
2019-07-15 20:29                                   ` Thiago Jung Bauermann
2019-07-15 20:36                                     ` Michael S. Tsirkin
2019-07-15 22:03                                       ` Thiago Jung Bauermann
2019-07-15 22:16                                         ` Michael S. Tsirkin
2019-07-15 23:05                                           ` Thiago Jung Bauermann
2019-07-15 23:24                                         ` Benjamin Herrenschmidt
2019-07-18  3:39                                 ` Thiago Jung Bauermann
2019-08-10 18:57 ` Michael S. Tsirkin
2019-08-10 22:07   ` Ram Pai
2019-08-11  5:56     ` Christoph Hellwig
2019-08-11  6:46       ` Ram Pai
2019-08-11  8:44         ` Michael S. Tsirkin
2019-08-12 12:13         ` Christoph Hellwig
2019-08-12 20:29           ` Ram Pai
2019-08-11  8:42       ` Michael S. Tsirkin
2019-08-11  8:55       ` Michael S. Tsirkin
2019-08-12 12:15         ` Christoph Hellwig
2019-09-06  5:07           ` Michael S. Tsirkin
2019-08-12  9:51       ` David Gibson
2019-08-13 13:26         ` Christoph Hellwig
2019-08-13 14:24           ` David Gibson
2019-08-13 15:45             ` Ram Pai
2019-08-26 17:48               ` Ram Pai
2019-08-11  8:12     ` Michael S. Tsirkin

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