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From: Sean Christopherson <seanjc@google.com>
To: Tarun Sahu <tarunsahu@google.com>
Cc: ackerleytng@google.com, fuad.tabba@linux.dev,
	 Andrew Morton <akpm@linux-foundation.org>,
	dmatlack@google.com,  Shuah Khan <skhan@linuxfoundation.org>,
	Jonathan Corbet <corbet@lwn.net>,
	david@redhat.com,  Pasha Tatashin <pasha.tatashin@soleen.com>,
	Pratyush Yadav <pratyush@kernel.org>,
	sagis@google.com,  Paolo Bonzini <pbonzini@redhat.com>,
	Mike Rapoport <rppt@kernel.org>, Alexander Graf <graf@amazon.com>,
	 linux-kselftest@vger.kernel.org, andre.przywara@arm.com,
	michael.roth@amd.com,  linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, will@kernel.org,  vannapurve@google.com,
	maz@kernel.org, fvdl@google.com, kvm@vger.kernel.org,
	 oliver.upton@linux.dev, kvmarm@lists.linux.dev,
	alexandru.elisei@arm.com,  skhawaja@google.com,
	aneesh.kumar@kernel.org, linux-doc@vger.kernel.org,
	 David Hildenbrand <david@kernel.org>,
	yan.y.zhao@intel.com, kexec@lists.infradead.org,
	 suzuki.poulose@arm.com
Subject: Re: [PATCH v4 04/11] KVM: Track weak reference to vm_file in struct kvm
Date: Mon, 10 Aug 2026 16:23:12 -0700	[thread overview]
Message-ID: <anpdYD1UaO0ffQgi@google.com> (raw)
In-Reply-To: <20260728121138.1103610-5-tarunsahu@google.com>

On Tue, Jul 28, 2026, Tarun Sahu wrote:
> - Add a weak reference 'vm_file' in struct kvm under

"vm_file" is effectively already claimed by vm_area_struct.vm_file.  *If* we go
this route, I would very strongly prefer to take a dependency on "vfio: Use
file-based reference counting for KVM"[*].  I'll poke that thread, we really
should land that one particular patch long before the s390-is-arm64 insanity.

Empashish on "if" because this all feels backwards.  It's not at all clear to
me why liveupdate goes directly to guest_memfd, but then requires a token associated
with the VM.

https://lore.kernel.org/all/20260731130902.654679-2-seiden@linux.ibm.com


  reply	other threads:[~2026-08-10 23:23 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-07-28 12:11 [PATCH v4 00/11] liveupdate: kvm: Guest_memfd preservation Tarun Sahu
2026-07-28 12:11 ` [PATCH v4 01/11] liveupdate: Add LIVEUPDATE_GUEST_MEMFD config option Tarun Sahu
2026-08-10 22:58   ` Sean Christopherson
2026-07-28 12:11 ` [PATCH v4 02/11] KVM: Introduce kvm_create_vm_file() helper Tarun Sahu
2026-07-30 17:36   ` Ackerley Tng
2026-08-10 10:14     ` tarunsahu
2026-08-10 23:05   ` Sean Christopherson
2026-07-28 12:11 ` [PATCH v4 03/11] KVM: Export kvm_uevent_notify_vm_create() Tarun Sahu
2026-07-28 12:11 ` [PATCH v4 04/11] KVM: Track weak reference to vm_file in struct kvm Tarun Sahu
2026-08-10 23:23   ` Sean Christopherson [this message]
2026-07-28 12:11 ` [PATCH v4 05/11] KVM: LUO: Support VM preservation across live updates Tarun Sahu
2026-08-10 23:42   ` Sean Christopherson
2026-07-28 12:11 ` [PATCH v4 06/11] KVM: guest_memfd: Move internal definitions to internal header Tarun Sahu
2026-07-30 18:12   ` Ackerley Tng
2026-07-28 12:11 ` [PATCH v4 07/11] KVM: guest_memfd: Add support for freezing mappings Tarun Sahu
2026-07-30 17:46   ` Ackerley Tng
2026-08-10 13:15     ` tarunsahu
2026-07-30 18:12   ` Ackerley Tng
2026-08-10 13:08     ` tarunsahu
2026-08-10 23:44   ` Sean Christopherson
2026-07-28 12:11 ` [PATCH v4 08/11] KVM: guest_memfd: Add support for preservation via LUO Tarun Sahu
2026-07-30 18:16   ` Ackerley Tng
2026-08-10 13:20     ` tarunsahu
2026-07-28 12:11 ` [PATCH v4 09/11] docs: liveupdate: Add documentation for VM and guest_memfd preservation Tarun Sahu
2026-07-28 12:11 ` [PATCH v4 10/11] KVM: selftests: Split ____vm_create() and add vm_create_from_fd() Tarun Sahu
2026-07-28 12:11 ` [PATCH v4 11/11] KVM: selftests: Add guest_memfd_preservation_test Tarun Sahu
2026-07-30 18:18   ` Ackerley Tng
2026-08-10 13:22     ` tarunsahu

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