From: Jason Gunthorpe <jgg@ziepe.ca>
To: Sean Christopherson <seanjc@google.com>
Cc: Ackerley Tng <ackerleytng@google.com>,
Alexey Kardashevskiy <aik@amd.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
Kevin Tian <kevin.tian@intel.com>, Joerg Roedel <joro@8bytes.org>,
Will Deacon <will@kernel.org>,
Robin Murphy <robin.murphy@arm.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Steve Sistare <steven.sistare@oracle.com>,
Nicolin Chen <nicolinc@nvidia.com>,
iommu@lists.linux.dev, linux-coco@lists.linux.dev,
Dan Williams <dan.j.williams@intel.com>,
Santosh Shukla <santosh.shukla@amd.com>,
"Pratik R . Sampat" <prsampat@amd.com>,
Fuad Tabba <tabba@google.com>,
Xu Yilun <yilun.xu@linux.intel.com>,
"Aneesh Kumar K . V" <aneesh.kumar@kernel.org>,
michael.roth@amd.com, vannapurve@google.com
Subject: Re: [RFC PATCH kernel] iommufd: Allow mapping from KVM's guest_memfd
Date: Thu, 26 Feb 2026 20:21:05 -0400 [thread overview]
Message-ID: <20260227002105.GC44359@ziepe.ca> (raw)
In-Reply-To: <aaDL8tYrVCWlQg79@google.com>
On Thu, Feb 26, 2026 at 02:40:50PM -0800, Sean Christopherson wrote:
> > If guestmemfd is fully pinned and cannot free memory outside of
> > truncate that may be good enough (though somehow I think that is not
> > the case)
>
> With in-place conversion, PUNCH_HOLE and private=>shared conversions are the only
> two ways to partial "remove" memory from guest_memfd, so it may really be that
> simple.
PUNCH_HOLE can be treated like truncate right?
I'm confused though - I thought in-place conversion ment that
private<->shared re-used the existing memory allocation? Why does it
"remove" memory?
Or perhaps more broadly, where is the shared memory kept/accessed in
these guest memfd systems?
Jason
next prev parent reply other threads:[~2026-02-27 0:21 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-25 7:52 [RFC PATCH kernel] iommufd: Allow mapping from KVM's guest_memfd Alexey Kardashevskiy
2026-02-25 13:55 ` Sean Christopherson
2026-02-26 6:47 ` Alexey Kardashevskiy
2026-02-26 19:27 ` Jason Gunthorpe
2026-02-27 11:03 ` Xu Yilun
2026-02-26 8:19 ` Ackerley Tng
2026-02-26 19:07 ` Jason Gunthorpe
2026-02-26 22:40 ` Sean Christopherson
2026-02-27 0:21 ` Jason Gunthorpe [this message]
2026-02-27 0:28 ` Sean Christopherson
2026-02-27 1:09 ` Jason Gunthorpe
2026-02-27 10:35 ` Xu Yilun
2026-02-27 13:18 ` Jason Gunthorpe
2026-02-28 4:14 ` Xu Yilun
2026-02-28 18:29 ` Jason Gunthorpe
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