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b=NwFI/ALUsZpTgLdEk4fckLQuZga1SjISh6MuG9hjGAF4TzjG1Ctz+su5+8c3yS1DWi d4XHaYNS/0/0H8HfbsGMARMDWaqxyAssvs+hG2xZDRJonIka7zdQIV+uGZsxGJFojss6 g+RPNcJWmU3huyUDHd+kkRzEdRYr5gdmHb6T64srsiG+RV5GEXur2doLTuXH+saI1gay O0I4F6Ru9j2Df8ZNTAHhhGWbN8gzVCrQAq3wcoH2enjlDo0xAsEB2uwzTR0T60v/v6Tk uWOe2ha9MVJmRFnoKykcCHLVgfn6Bsx73aRPvIjNeh01TCsLIj9pY5Intv60W3bNV+u/ 0EPQ== X-Forwarded-Encrypted: i=1; AHgh+Rr/iLim9fdB6UwKvAoq2cyNQs803MUOT0WZTYPMKt53pACX1FfKRelyK2NJ0BAwWBKWB7MqqdC7kw==@kvack.org X-Gm-Message-State: AOJu0Yz/5Rx2HcE0+livro8rovi06yD+tEzm3npgW02FdwI+M8Rnj9Te MYatcFJCyHeK9PSkpxoolXn6x2Qgi8VqDpQkMIYDCzLmoOhE2hpghYf4hVHMPDyoBsyvlQC4DjT rSWhotBmyZxcCTc/gxA== X-Received: from edrs9.prod.google.com ([2002:aa7:c549:0:b0:6a3:6b8a:8011]) (user=tarunsahu job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6402:434c:b0:69a:928:9405 with SMTP id 4fb4d7f45d1cf-6a38a8dbbefmr17632626a12.1.1787069474414; Tue, 18 Aug 2026 09:11:14 -0700 (PDT) Date: Tue, 18 Aug 2026 16:11:13 +0000 In-Reply-To: Mime-Version: 1.0 References: <20260728121138.1103610-1-tarunsahu@google.com> <20260728121138.1103610-2-tarunsahu@google.com> <9huzqzk4zt3n.fsf@tarunix.c.googlers.com> Message-ID: <9huzlda3v272.fsf@tarunix.c.googlers.com> Subject: Re: [PATCH v4 01/11] liveupdate: Add LIVEUPDATE_GUEST_MEMFD config option From: tarunsahu@google.com To: Sean Christopherson Cc: ackerleytng@google.com, fuad.tabba@linux.dev, Andrew Morton , dmatlack@google.com, Shuah Khan , Jonathan Corbet , david@redhat.com, Pasha Tatashin , Pratyush Yadav , sagis@google.com, Paolo Bonzini , Mike Rapoport , Alexander Graf , 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 , yan.y.zhao@intel.com, kexec@lists.infradead.org, suzuki.poulose@arm.com Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: 542BC80014 X-Stat-Signature: mroie9k3p8w6wt1nyud9ar5mmba4kgd5 X-Rspam-User: X-Rspamd-Server: rspam11 X-HE-Tag: 1787069476-254913 X-HE-Meta: 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 ZmFXZ/hX 2l2FmsxXc6xU7ET4gpsZXCAwbC8tEugirGFaOwj3ZjfqJjB/RCh9wYXy/PYdDjyyO1NhFOyBP1NomyukUajAxR+3pjKh6Z8T9+PpT8WqPPzlQPGd6aW5CeVOJxFtHT1w1yftc31ab8AfGCmhlf9P1cWqJ4D+lLIlHuljivtd68KYzu8U2ESiIe9GzsRfAr75FReBVqoJEOJmisrFLOp2r5KaL6gTW2MNoXYEuwpo5qBvJ55UxAooTw1QFDnR+B/1nFKbj52ZfIx10pdeMdBCInSQNCuNfwxl6E8hXRZAumUX69h0afGtksWDdqIGsLAuiAFUc8iYdG8zzZPHMzMKVviVeqKyZ3ndWYeOZG3JLmP/kYFnNtbt7B5Hf3dSOsakoRHD3GbTlr97jcH6Rw8zweK20O1GfhbbJlTNrvXbjYqIWR2DkhLXKsO3pZmXMeozphGfYAEcTKeLh18Ub0ypGjtkNDvDm5BGqmW25P3bnNKDtUvP9BButf++aFXSaOTDTCrvZY4eOQzVVQQfZibvDECxrYRNUGneWoFy8pTWljB3x6W8wfBjiEYIb3+qlxHNBA3muMxRUOyny9vgDugfAa1iQ1cxkJ2GN9W++lN3jLv0lTWJolg8bTQCYRt4bJbVnBdxJ Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Sean Christopherson writes: > On Tue, Aug 11, 2026, tarunsahu@google.com wrote: >> Sean Christopherson writes: >> >> > On Tue, Jul 28, 2026, Tarun Sahu wrote: >> >> Introduce the LIVEUPDATE_GUEST_MEMFD Kconfig option. This option >> >> enables live update support for KVM guest_memfd files, enabling >> >> guest_memfd-backed memory preservation across kernel upgrades. >> >> >> >> Currently this support only guest_memfd files that are full-shared >> >> (INIT_SHARED and no support for private_mem). >> > >> > Why? Specifically, why do we need/want a separate Kconfig for guest_memfd >> > liveupdate versus KVM liveupdate? I can _maybe_ see a KVM-wide Kconfig, but >> > even that seems like a stretch given that (AFAIK) hypervisors are the one and >> > only use-case for liveupdate. >> >> LIVEUPDATE is used in many subsystem. It is possible to enable >> liveupdate and kvm without enabling KVM_GUEST_MEMFD. So GUEST_MEMFD >> preservation must depend on CONFIG_LIVEUPDATE and KVM_GUEST_MEMFD both. >> LIVEUPDATE_GUEST_MEMFD Kconfig is wrapper on both of them. It need not >> to be visible in menu, So I can make it hidden. WDYT? >> >> Also, KVM VM_FILE preservation and GUEST_MEMFD preservation both depends >> on LIVEUPDATE_GUEST_MEMFD in this patch series. [PATCH 05/11]* >> Which is wrong. So I will update KVM VM_FILE preservation to depend only >> on CONFIG_LIVEUPDATE. > > Or just handle it all in the makefile? E.g. > > diff --git virt/kvm/Makefile.kvm virt/kvm/Makefile.kvm > index d047d4cf58c9..e6f098498795 100644 > --- virt/kvm/Makefile.kvm > +++ virt/kvm/Makefile.kvm > @@ -13,3 +13,8 @@ kvm-$(CONFIG_HAVE_KVM_IRQ_ROUTING) += $(KVM)/irqchip.o > kvm-$(CONFIG_HAVE_KVM_DIRTY_RING) += $(KVM)/dirty_ring.o > kvm-$(CONFIG_HAVE_KVM_PFNCACHE) += $(KVM)/pfncache.o > kvm-$(CONFIG_KVM_GUEST_MEMFD) += $(KVM)/guest_memfd.o > + > +ifdef CONFIG_LIVEUPDATE > +kvm-y += $(KVM)/kvm_luo.o > +kvm-$(CONFIG_KVM_GUEST_MEMFD) += $(KVM)/guest_memfd_luo.o > +endif Sounds Good to me. Will take care of it. Thanks.