From: Sean Christopherson <seanjc@google.com>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: Marc Zyngier <maz@kernel.org>, Ankit Agrawal <ankita@nvidia.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Oliver Upton <oliver.upton@linux.dev>,
"joey.gouly@arm.com" <joey.gouly@arm.com>,
"suzuki.poulose@arm.com" <suzuki.poulose@arm.com>,
"yuzenghui@huawei.com" <yuzenghui@huawei.com>,
"will@kernel.org" <will@kernel.org>,
"ryan.roberts@arm.com" <ryan.roberts@arm.com>,
"shahuang@redhat.com" <shahuang@redhat.com>,
"lpieralisi@kernel.org" <lpieralisi@kernel.org>,
"david@redhat.com" <david@redhat.com>,
Aniket Agashe <aniketa@nvidia.com>, Neo Jia <cjia@nvidia.com>,
Kirti Wankhede <kwankhede@nvidia.com>,
"Tarun Gupta (SW-GPU)" <targupta@nvidia.com>,
Vikram Sethi <vsethi@nvidia.com>,
Andy Currid <acurrid@nvidia.com>,
Alistair Popple <apopple@nvidia.com>,
John Hubbard <jhubbard@nvidia.com>,
Dan Williams <danw@nvidia.com>, Zhi Wang <zhiw@nvidia.com>,
Matt Ochs <mochs@nvidia.com>, Uday Dhoke <udhoke@nvidia.com>,
Dheeraj Nigam <dnigam@nvidia.com>,
Krishnakant Jaju <kjaju@nvidia.com>,
"alex.williamson@redhat.com" <alex.williamson@redhat.com>,
"sebastianene@google.com" <sebastianene@google.com>,
"coltonlewis@google.com" <coltonlewis@google.com>,
"kevin.tian@intel.com" <kevin.tian@intel.com>,
"yi.l.liu@intel.com" <yi.l.liu@intel.com>,
"ardb@kernel.org" <ardb@kernel.org>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"gshan@redhat.com" <gshan@redhat.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"ddutile@redhat.com" <ddutile@redhat.com>,
"tabba@google.com" <tabba@google.com>,
"qperret@google.com" <qperret@google.com>,
"kvmarm@lists.linux.dev" <kvmarm@lists.linux.dev>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v3 1/1] KVM: arm64: Allow cacheable stage 2 mapping using VMA flags
Date: Mon, 7 Apr 2025 09:43:50 -0700 [thread overview]
Message-ID: <Z_QAxiEWEyMpfLgL@google.com> (raw)
In-Reply-To: <20250407161540.GG1557073@nvidia.com>
On Mon, Apr 07, 2025, Jason Gunthorpe wrote:
> On Mon, Apr 07, 2025 at 08:20:09AM -0700, Sean Christopherson wrote:
> > On Mon, Mar 31, 2025, Jason Gunthorpe wrote:
> > > On Wed, Mar 26, 2025 at 11:24:32AM -0700, Sean Christopherson wrote:
> > > > > I don't know how you reconcile the lack of host mapping and cache
> > > > > maintenance. The latter cannot take place without the former.
> > > >
> > > > I assume cache maintenance only requires _a_ mapping to the physical memory.
> > > > With guest_memfd, KVM has the pfn (which happens to always be struct page memory
> > > > today), and so can establish a VA=>PA mapping as needed.
> > >
> > > This is why we are forcing FWB in this work, because we don't have a
> > > VA mapping and KVM doesn't have the code to create one on demand.
> >
> > I don't follow. As it exists today, guest_memfd doesn't touch the direct map,
> > i.e. there's already a kernel mapping, KVM doesn't need to create one.
>
> This is not about guest_memfd..
Heh, my part of the thread was. I was responding to Marc's comment:
: Remind me how this work with stuff such as guestmemfd, which, by
: definition, doesn't have a userspace mapping?
I'm pretty sure we're on the same page.
next prev parent reply other threads:[~2025-04-07 16:43 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-03-10 10:30 [PATCH v3 0/1] KVM: arm64: Map GPU device memory as cacheable ankita
2025-03-10 10:30 ` [PATCH v3 1/1] KVM: arm64: Allow cacheable stage 2 mapping using VMA flags ankita
2025-03-10 11:54 ` Marc Zyngier
2025-03-11 3:42 ` Ankit Agrawal
2025-03-11 11:18 ` Marc Zyngier
2025-03-11 12:07 ` Ankit Agrawal
2025-03-12 8:21 ` Marc Zyngier
2025-03-17 5:55 ` Ankit Agrawal
2025-03-17 9:27 ` Marc Zyngier
2025-03-17 19:54 ` Catalin Marinas
2025-03-18 9:39 ` Marc Zyngier
2025-03-18 12:55 ` Jason Gunthorpe
2025-03-18 19:27 ` Catalin Marinas
2025-03-18 19:35 ` David Hildenbrand
2025-03-18 19:40 ` Oliver Upton
2025-03-20 3:30 ` bibo mao
2025-03-20 7:24 ` bibo mao
2025-03-18 23:17 ` Jason Gunthorpe
2025-03-19 18:03 ` Catalin Marinas
2025-03-18 19:30 ` Oliver Upton
2025-03-18 23:09 ` Jason Gunthorpe
2025-03-19 7:01 ` Oliver Upton
2025-03-19 17:04 ` Jason Gunthorpe
2025-03-19 18:11 ` Catalin Marinas
2025-03-19 19:22 ` Jason Gunthorpe
2025-03-19 21:48 ` Catalin Marinas
2025-03-26 8:31 ` Ankit Agrawal
2025-03-26 14:53 ` Sean Christopherson
2025-03-26 15:42 ` Marc Zyngier
2025-03-26 16:10 ` Sean Christopherson
2025-03-26 18:02 ` Marc Zyngier
2025-03-26 18:24 ` Sean Christopherson
2025-03-26 18:51 ` Oliver Upton
2025-03-31 14:44 ` Jason Gunthorpe
2025-03-31 14:56 ` Jason Gunthorpe
2025-04-07 15:20 ` Sean Christopherson
2025-04-07 16:15 ` Jason Gunthorpe
2025-04-07 16:43 ` Sean Christopherson [this message]
2025-04-16 8:51 ` Ankit Agrawal
2025-04-21 16:03 ` Ankit Agrawal
2025-04-22 7:49 ` Oliver Upton
2025-04-22 13:54 ` Jason Gunthorpe
2025-04-22 16:50 ` Catalin Marinas
2025-04-22 17:03 ` Jason Gunthorpe
2025-04-22 21:28 ` Oliver Upton
2025-04-22 23:35 ` Jason Gunthorpe
2025-04-23 10:45 ` Catalin Marinas
2025-04-23 12:02 ` Jason Gunthorpe
2025-04-23 12:26 ` Catalin Marinas
2025-04-23 13:03 ` Jason Gunthorpe
2025-04-29 10:47 ` Ankit Agrawal
2025-04-29 13:27 ` Catalin Marinas
2025-04-29 14:14 ` Jason Gunthorpe
2025-04-29 16:03 ` Catalin Marinas
2025-04-29 16:44 ` Jason Gunthorpe
2025-04-29 18:09 ` Catalin Marinas
2025-04-29 18:19 ` Jason Gunthorpe
2025-05-07 15:26 ` Ankit Agrawal
2025-05-09 12:47 ` Catalin Marinas
2025-04-22 14:53 ` Sean Christopherson
2025-03-18 12:57 ` Jason Gunthorpe
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=Z_QAxiEWEyMpfLgL@google.com \
--to=seanjc@google.com \
--cc=acurrid@nvidia.com \
--cc=akpm@linux-foundation.org \
--cc=alex.williamson@redhat.com \
--cc=aniketa@nvidia.com \
--cc=ankita@nvidia.com \
--cc=apopple@nvidia.com \
--cc=ardb@kernel.org \
--cc=catalin.marinas@arm.com \
--cc=cjia@nvidia.com \
--cc=coltonlewis@google.com \
--cc=danw@nvidia.com \
--cc=david@redhat.com \
--cc=ddutile@redhat.com \
--cc=dnigam@nvidia.com \
--cc=gshan@redhat.com \
--cc=jgg@nvidia.com \
--cc=jhubbard@nvidia.com \
--cc=joey.gouly@arm.com \
--cc=kevin.tian@intel.com \
--cc=kjaju@nvidia.com \
--cc=kvmarm@lists.linux.dev \
--cc=kwankhede@nvidia.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=lpieralisi@kernel.org \
--cc=maz@kernel.org \
--cc=mochs@nvidia.com \
--cc=oliver.upton@linux.dev \
--cc=qperret@google.com \
--cc=ryan.roberts@arm.com \
--cc=sebastianene@google.com \
--cc=shahuang@redhat.com \
--cc=suzuki.poulose@arm.com \
--cc=tabba@google.com \
--cc=targupta@nvidia.com \
--cc=udhoke@nvidia.com \
--cc=vsethi@nvidia.com \
--cc=will@kernel.org \
--cc=yi.l.liu@intel.com \
--cc=yuzenghui@huawei.com \
--cc=zhiw@nvidia.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.