From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ej1-f72.google.com (mail-ej1-f72.google.com [209.85.218.72]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8376B47CC8D for ; Tue, 18 Aug 2026 16:11:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.218.72 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787069478; cv=none; b=Idnroz1K3zvTMhfIyiU/zyOmgJyktO/BbOKIGNdqqmOXahjDELBwvNoQ5rH1kSnK+d9l0ajU7whbQQH4WacOFAIMEGfy9GgLQC7zymb+uMADam5+W6BOJXxzNJzVHsiW8GRJgkrhpx2dUEc25kPIyOLxpx+H/9/wQpKyuRoVo9A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787069478; c=relaxed/simple; bh=wQ68heHkCupu6WSEgt5iLdHD+hbjTh1juZ0Wnx2wjUk=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=f+QRD1CvTtk/De84uoWYhz6b4pt3jCFhRtp9oeLJjpDNBR9ecOzOaAHMgD9F43fs98oIjfUzu/jzeeJ9YuJsGWUK+55iZwEAAp2znPXMPaGiCelMmOnYVxaqXr75H17g0NMjX77vUCFKqDf3C1gPxUCfGGpTXW6l1insXB5Fr50= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--tarunsahu.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=l+LvMm8s; arc=none smtp.client-ip=209.85.218.72 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--tarunsahu.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="l+LvMm8s" Received: by mail-ej1-f72.google.com with SMTP id a640c23a62f3a-c20e5890680so381563266b.1 for ; Tue, 18 Aug 2026 09:11:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1787069475; x=1787674275; darn=vger.kernel.org; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:from:to:cc:subject:date:message-id:reply-to :content-type; bh=gq4c916t8aM4R9/gOTYj07vE672c6Dn+UdOcLkpJL3k=; b=l+LvMm8snBBsWECYIUzFC/FYZKd8BCHWXXdjW86FH+8zen02glu3JguuWDnQPCB2Vj 6JSbrezX0QkGQUe7DCHqb7lIHyJ6DreZ5OV5OsgVKckVwYwiQgHUkQRHFDTHjaBxfoEC 81KrXCr0adh8evguBiehgNFV4QaRWwogOo4v9jEyImzj+Dm9NH6PftFvkqkJbpNGR4Lf 4vM95YMYHA0ePcyiNZ+pPUaR3GMn+U2G+MAN12W0O4Qq9iVjLLpsmaJtp9ntOcZ+ooPg sAJKrJRK09qJKgQtTrADZeeOXEwVc9DcrP4q8zO9K8J/ndw2VAAgoEk+TLA8A1fWS+gD Dj/w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1787069475; x=1787674275; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=gq4c916t8aM4R9/gOTYj07vE672c6Dn+UdOcLkpJL3k=; b=Ht6jKZBHJ4IgqnENj69RLIMN6pmRduQj0LJVo2sar6qufdHiDL8EUri7azkgCQNetO xtjZEtB5lk03NokNbJBsdxT6u2DfXYMXHm+weAtgrHx8mSHu29fzB90dIQ5JAymcgkv5 diWHhiNiG+k+GQgTnPaHJbtphgxUDkITEZr1loEcQMUdmpuqenfNG+rhcteVzvjUY5aC dVTFjfNXMcSvnIwVq6NEKB6EzzbByVt714sco6/mDys9JknOgNKTQ51Q4I+Gx/pZitzF nVhsjtsLRjV5aH2GVKdK+eHv0Vt7S+naK+VbTOjdKurkdPfMIhGdv6rnHdy5a/8zTh76 xVww== X-Forwarded-Encrypted: i=1; AHgh+RrFOMOA9YxyUoKcioYvRRZkHj4m/R01rbgNZ8QN3rmd16RwAJgu95z/ayJkUEm3RUC1bkU=@vger.kernel.org X-Gm-Message-State: AOJu0YwevYKQvuaY3F4fAy3q76f53Hz1pXUBu6v/q0yMyBaooBXBN/wO eJTxnsYJWaramKuKdV/5VCloq3qIKObINsC212f2CCbtyJeDoGnqlfBgeQJtfeBMs6TU+L8+g3l 0mqMio/ZF8f3yMsru8Q== 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: Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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" 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.