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AKwUvByeZd6dmAnYT3ghKEcVPRpWrtwk3u5B28N6ky2EjEhw6UeQ6Cr0OBCS2UKu9cHJ7nmAKnreS6g=@lists.linux.dev X-Gm-Message-State: AFuF++nby8+ppiNNmKMUq9aMo70IZND9edzwftYmetjosQHKkqKv4SNZ 3yaeYcbITV7/sMCpt0V/hfloBabMlJy1nlY9LT4ROFtGQcsVUBBUUVPaSgbXHcjjh6xWjZ4o5WH DRSx6dA== X-Received: from plgf7.prod.google.com ([2002:a17:902:ce87:b0:2cc:6063:a658]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:903:26c6:b0:2d8:d4cc:be67 with SMTP id d9443c01a7336-2daec73f1d2mr14199535ad.20.1788309534336; Tue, 01 Sep 2026 17:38:54 -0700 (PDT) Date: Tue, 1 Sep 2026 17:38:53 -0700 In-Reply-To: <20260831144802.834315-4-seiden@linux.ibm.com> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260831144802.834315-1-seiden@linux.ibm.com> <20260831144802.834315-4-seiden@linux.ibm.com> Message-ID: Subject: Re: [PATCH v7 03/23] KVM: Allow KVM implementations to switch off MMIO independent of Kconfig From: Sean Christopherson To: Steffen Eiden Cc: kvm@vger.kernel.org, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, Alexander Gordeev , Andreas Grapentin , Arnd Bergmann , Catalin Marinas , Christian Borntraeger , Claudio Imbrenda , David Hildenbrand , Friedrich Welter , Fuad Tabba , Gautam Gala , Hariharan Mari , Heiko Carstens , Hendrik Brueckner , Ilya Leoshkevich , Janosch Frank , Joey Gouly , Marc Zyngier , Nico Boehr , Nina Schoetterl-Glausch , Oliver Upton , Paolo Bonzini , Suzuki K Poulose , Sven Schnelle , Ulrich Weigand , Vasily Gorbik , Will Deacon , Zenghui Yu Content-Type: text/plain; charset="us-ascii" On Mon, Aug 31, 2026, Steffen Eiden wrote: > Only defining KVM_MMIO is not flexible enough for multi-KVM systems > where one KVM implements MMIO but others do not. Solve this by > additionally testing for the non-existence of KVM_NO_MMIO before > including MMIO code to KVM. Ewwwww. IIUC, s390 ends up with two KVM modules, i.e. there really are two different KVMs being built. Rather than have a KVM_MMIO and NO_KVM_MMIO, I vote very strongly to drop CONFIG_KVM_MMIO entirely and replace it with __KVM_HAVE_ARCH_MMIO, a la __KVM_HAVE_ARCH_VM_FREE and others. Tracking two separate macros is going to be annoying to maintain, and will definitely be confusing for non-s390 people. It'll mean linking in an emtpy coalesced_mmio.o on s390 when building without arm64 support, but I'm guessing that won't be at all common for s390 builds.