From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: virtio-comment-return-1544-cohuck=redhat.com@lists.oasis-open.org Sender: List-Post: List-Help: List-Unsubscribe: List-Subscribe: Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id DA80B9865B9 for ; Wed, 2 Dec 2020 10:15:39 +0000 (UTC) Date: Wed, 2 Dec 2020 11:15:23 +0100 From: Cornelia Huck Message-ID: <20201202111523.5f2c62c4.cohuck@redhat.com> In-Reply-To: <7c3b2adb-492b-7aec-d4cc-8ca218889eba@redhat.com> References: <20201116191629.47661-1-david@redhat.com> <20201120161330.740d694e.cohuck@redhat.com> <97ef1bc6-3c6d-b2d2-8d26-4fcb69cafc1b@redhat.com> <20201127120226.100f112a.cohuck@redhat.com> <7c3b2adb-492b-7aec-d4cc-8ca218889eba@redhat.com> MIME-Version: 1.0 Subject: Re: [virtio-comment] Re: [PATCH v1] virtio-mem: minor clarification regarding read-access to unplugged blocks Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit To: David Hildenbrand Cc: virtio-comment@lists.oasis-open.org, teawater , Marek Kedzierski , "Michael S . Tsirkin" List-ID: On Wed, 2 Dec 2020 10:25:16 +0100 David Hildenbrand wrote: > On 27.11.20 12:02, Cornelia Huck wrote: > > On Fri, 27 Nov 2020 11:39:50 +0100 > > David Hildenbrand wrote: > > > >> On 20.11.20 16:13, Cornelia Huck wrote: > >>> On Mon, 16 Nov 2020 20:16:29 +0100 > >>> David Hildenbrand wrote: > >>> > >>>> Let's clarify that we don't expect all DMA to work with unplugged blocks. > >>>> We really only give guarantees when reading from unplugged memory blocks > >>>> via the CPU, e.g., as done by Linux when creating a system dump via > >>>> kdump: the new kernel will copy the content of the old (crashed) kernel > >>>> via the CPU to user space, from where it will find its final destination > >>>> inside the dump file. Note that dumping via makedumpfile under Linux will > >>>> avoid reading unplugged blocks completely. > >>>> > >>>> This is a preparation for device passthrough to VMs, whereby such > >>>> dedicated devices might not be able to read from unplugged memory blocks. > >>>> > >>>> Let's document that this scenario is possible, and why this handling is > >>>> in place at all. > >>>> > >>>> Cc: teawater > >>>> Cc: Marek Kedzierski > >>>> Cc: Michael S. Tsirkin > >>>> Cc: Cornelia Huck > >>>> Signed-off-by: David Hildenbrand > >>>> --- > >>>> virtio-mem.tex | 9 +++++++-- > >>>> 1 file changed, 7 insertions(+), 2 deletions(-) > >>> > >>> Looks reasonable to me. > >>> > >>> Acked-by: Cornelia Huck > >> > >> Thanks! > >> > >> I assume I'll need a github issue etc. to get this in, right? > >> > > > > Yes; just open the issue, point to this patch in the archives, and > > reply with the issue here. > > > > (I don't think this is trivial enough to push without voting.) > > > > Makes sense. I'll wait a bit more. Thanks! > I think you can just go ahead and request a vote... no need to wait further IMHO. This publicly archived list offers a means to provide input to the OASIS Virtual I/O Device (VIRTIO) TC. In order to verify user consent to the Feedback License terms and to minimize spam in the list archive, subscription is required before posting. Subscribe: virtio-comment-subscribe@lists.oasis-open.org Unsubscribe: virtio-comment-unsubscribe@lists.oasis-open.org List help: virtio-comment-help@lists.oasis-open.org List archive: https://lists.oasis-open.org/archives/virtio-comment/ Feedback License: https://www.oasis-open.org/who/ipr/feedback_license.pdf List Guidelines: https://www.oasis-open.org/policies-guidelines/mailing-lists Committee: https://www.oasis-open.org/committees/virtio/ Join OASIS: https://www.oasis-open.org/join/