From: Sean Christopherson <sean.j.christopherson@intel.com>
To: "Tian, Kevin" <kevin.tian@intel.com>
Cc: Wanpeng Li <wanpengli@tencent.com>,
kvm list <kvm@vger.kernel.org>, Joerg Roedel <joro@8bytes.org>,
ML dri-devel <dri-devel@lists.freedesktop.org>,
Gurchetan Singh <gurchetansingh@chromium.org>,
Gerd Hoffmann <kraxel@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Jim Mattson <jmattson@google.com>
Subject: Re: [RFC PATCH 0/3] KVM: x86: honor guest memory type
Date: Fri, 21 Feb 2020 07:59:39 -0800 [thread overview]
Message-ID: <20200221155939.GG12665@linux.intel.com> (raw)
In-Reply-To: <AADFC41AFE54684AB9EE6CBC0274A5D19D79359E@SHSMSX104.ccr.corp.intel.com>
On Thu, Feb 20, 2020 at 09:39:05PM -0800, Tian, Kevin wrote:
> > From: Chia-I Wu <olvaffe@gmail.com>
> > Sent: Friday, February 21, 2020 12:51 PM
> > If you think it is the best for KVM to inspect hva to determine the memory
> > type with page granularity, that is reasonable and should work for us too.
> > The userspace can do something (e.g., add a GPU driver dependency to the
> > hypervisor such that the dma-buf is imported as a GPU memory and mapped
> > using
> > vkMapMemory) or I can work with dma-buf maintainers to see if dma-buf's
> > semantics can be changed.
>
> I think you need consider the live migration requirement as Paolo pointed out.
> The migration thread needs to read/write the region, then it must use the
> same type as GPU process and guest to read/write the region. In such case,
> the hva mapped by Qemu should have the desired type as the guest. However,
> adding GPU driver dependency to Qemu might trigger some concern. I'm not
> sure whether there is generic mechanism though, to share dmabuf fd between GPU
> process and Qemu while allowing Qemu to follow the desired type w/o using
> vkMapMemory...
Alternatively, KVM could make KVM_MEM_DMA and KVM_MEM_LOG_DIRTY_PAGES
mutually exclusive, i.e. force a transition to WB memtype for the guest
(with appropriate zapping) when migration is activated. I think that
would work?
> Note this is orthogonal to whether introducing a new uapi or implicitly checking
> hva to favor guest memory type. It's purely about Qemu itself. Ideally anyone
> with the desire to access a dma-buf object should follow the expected semantics.
> It's interesting that dma-buf sub-system doesn't provide a centralized
> synchronization about memory type between multiple mmap paths.
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel
next prev parent reply other threads:[~2020-02-21 15:59 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-13 21:30 [RFC PATCH 0/3] KVM: x86: honor guest memory type Chia-I Wu
2020-02-13 21:30 ` [RFC PATCH 1/3] KVM: vmx: rewrite the comment in vmx_get_mt_mask Chia-I Wu
2020-02-14 9:36 ` Paolo Bonzini
2020-02-13 21:30 ` [RFC PATCH 2/3] RFC: KVM: add KVM_MEM_DMA Chia-I Wu
2020-02-13 21:30 ` [RFC PATCH 3/3] RFC: KVM: x86: support KVM_CAP_DMA_MEM Chia-I Wu
2020-02-13 21:41 ` [RFC PATCH 0/3] KVM: x86: honor guest memory type Paolo Bonzini
2020-02-13 22:18 ` Chia-I Wu
2020-02-14 10:26 ` Paolo Bonzini
2020-02-14 19:52 ` Sean Christopherson
2020-02-14 21:47 ` Chia-I Wu
2020-02-14 21:56 ` Jim Mattson
2020-02-14 22:03 ` Sean Christopherson
2020-02-18 16:28 ` Paolo Bonzini
2020-02-18 22:58 ` Sean Christopherson
2020-02-19 9:52 ` Tian, Kevin
2020-02-19 19:36 ` Chia-I Wu
2020-02-20 2:04 ` Tian, Kevin
2020-02-20 2:38 ` Tian, Kevin
2020-02-20 22:23 ` Chia-I Wu
2020-02-21 0:23 ` Tian, Kevin
2020-02-21 4:45 ` Chia-I Wu
2020-02-21 4:51 ` Chia-I Wu
2020-02-21 5:39 ` Tian, Kevin
2020-02-21 15:59 ` Sean Christopherson [this message]
2020-02-21 18:21 ` Chia-I Wu
2020-02-25 1:29 ` Tian, Kevin
2020-02-14 21:15 ` Chia-I Wu
2020-02-19 10:00 ` Tian, Kevin
2020-02-19 19:18 ` Chia-I Wu
2020-02-20 2:13 ` Tian, Kevin
2020-02-20 23:02 ` Chia-I Wu
2020-02-24 10:57 ` Gerd Hoffmann
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=20200221155939.GG12665@linux.intel.com \
--to=sean.j.christopherson@intel.com \
--cc=dri-devel@lists.freedesktop.org \
--cc=gurchetansingh@chromium.org \
--cc=jmattson@google.com \
--cc=joro@8bytes.org \
--cc=kevin.tian@intel.com \
--cc=kraxel@redhat.com \
--cc=kvm@vger.kernel.org \
--cc=pbonzini@redhat.com \
--cc=vkuznets@redhat.com \
--cc=wanpengli@tencent.com \
/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).