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charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: F1534100013 X-Stat-Signature: mk1n58buxnnaxp3ooftys4kmrg7w45np X-Rspam-User: X-HE-Tag: 1730215932-307822 X-HE-Meta: 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 55w1YsFK QXcf23UdWN9vpMbqiSZjES7J3x0Zfq513eTsHTdh/M5odugVLPOKkfEOWPYLEzptEG1V+zr/AZdoUgWXy3bVuR3CSw0vEdHCi4QoauGbyWbu8sMMoWlT6PxXu9CqY4v17QeftLeh3NLXyHItiDwao8Na3ffLiE2uXcC+Of8co2XdiBwfA+82t2wvwTpIDRgzFQwSCZa4MBBi8Z3hTISojt4BgTd+EObeXxPMkUuEQqFsMi3/VBGNXHnxFSNkt5qqW8BtaloyJokZv5/eggNxUjHqFvrHfTjP/WMyx X-Bogosity: Ham, tests=bogofilter, spamicity=0.000002, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sat, Oct 26, 2024 at 11:37=E2=80=AFAM David Rientjes wrote: > > On Wed, 16 Oct 2024, David Rientjes wrote: > > > ----->o----- > > My takeaway: based on the feedback that was provided in the discussion: > > > > - we need an allocator abstraction for persistent memory that can retu= rn > > memory with various characteristics: 1GB or not, kernel direct map o= r > > not, HVO or not, etc. > > > > - built on top of that, we need the ability to carve out very large > > ranges of memory (cloud provider use case) with NUMA awareness on th= e > > kernel command line > > > > Following up on this, I think this physical memory allocator would also b= e > possible to use as a backend for hugetlb. Hopefully this would be an > allocator that would be generally useful for multiple purposes, something > like a mm/phys_alloc.c. > > Frank van der Linden may also have thoughts on the above? > > > - we also need the ability to be able to dynamically resize this or > > provide hints at allocation time that memory must be persisted acros= s > > kexec to support the non-cloud provider use case > > > > - we need a filesystem abstraction that map memory of the type that is > > requested, including guest_memfd and then deal with all the fun of > > multitenancy since it would be drawing from a finite per-NUMA node > > pool of persistent memory > > > > - absolutely critical to this discussion is defining what is the core > > infrastructure that is required for a generally acceptable solution > > and then what builds off of that to be more special cased (like the > > cloud provider use case or persistent tmpfs use case) > > > > We're looking to continue that discussion here and then come together > > again in a few weeks. > > > > We'll be looking to schedule some more time to talk about this topic in > the Wednesday, November 13 instance of the Linux MM Alignment Session. > > After that, I think it would be quite useful to break out the set of > people that are interested in persisting guest memory across kexec and KH= O > into a separate series to accelerate discussion and next stpes. Getting > the requirements and design locked down are critical, so happy to > facilitate that to any extent possible and welcome everybody interested i= n > discussing it. I think there is a nice overlap between requirements for the guest memory persistence and guest_memfd 1G page support for confidential/non-confidential VMs. Memory persistence of guest_memfd backed CoCo VMs and KHO will be a critical usecase for us at Google as well, so I am interested in further discussion here. Regards, Vishal > > James, for the guestmemfs discussions, would this work for you? > > Alexander, same question for you regarding the KHO work? > > It's a global community, so the timing won't work for eveyrbody. We'd > plan on sending out summaries of these discussions, such as in this email= , > to solicit feedback and ideas from everybody. > > If you're not on the To: or Cc: list already, please email me separatel i= f > you're interested in participating and then we can find a regular time. > > This is exciting!