From: Sean Christopherson <seanjc@google.com>
To: Steffen Eiden <seiden@linux.ibm.com>
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 <agordeev@linux.ibm.com>,
Andreas Grapentin <gra@linux.ibm.com>,
Arnd Bergmann <arnd@arndb.de>,
Catalin Marinas <catalin.marinas@arm.com>,
Christian Borntraeger <borntraeger@linux.ibm.com>,
Claudio Imbrenda <imbrenda@linux.ibm.com>,
David Hildenbrand <david@kernel.org>,
Friedrich Welter <fritz@linux.ibm.com>,
Fuad Tabba <tabba@google.com>, Gautam Gala <ggala@linux.ibm.com>,
Hariharan Mari <hari55@linux.ibm.com>,
Heiko Carstens <hca@linux.ibm.com>,
Hendrik Brueckner <brueckner@linux.ibm.com>,
Ilya Leoshkevich <iii@linux.ibm.com>,
Janosch Frank <frankja@linux.ibm.com>,
Joey Gouly <joey.gouly@arm.com>, Marc Zyngier <maz@kernel.org>,
Nico Boehr <nrb@linux.ibm.com>,
Nina Schoetterl-Glausch <oss@nina.schoetterlglausch.eu>,
Oliver Upton <oupton@kernel.org>,
Paolo Bonzini <pbonzini@redhat.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Sven Schnelle <svens@linux.ibm.com>,
Ulrich Weigand <Ulrich.Weigand@de.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>, Will Deacon <will@kernel.org>,
Zenghui Yu <yuzenghui@huawei.com>
Subject: Re: [PATCH v7 03/23] KVM: Allow KVM implementations to switch off MMIO independent of Kconfig
Date: Tue, 1 Sep 2026 17:38:53 -0700 [thread overview]
Message-ID: <apdwHcdy2iYRTrww@google.com> (raw)
In-Reply-To: <20260831144802.834315-4-seiden@linux.ibm.com>
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.
next prev parent reply other threads:[~2026-09-02 0:39 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-31 14:47 [PATCH v7 00/23] KVM: s390: Introduce arm64 KVM Steffen Eiden
2026-08-31 14:47 ` [PATCH v7 01/23] vfio: Use file-based reference counting for KVM Steffen Eiden
2026-08-31 14:47 ` [PATCH v7 02/23] KVM: Make device name configurable Steffen Eiden
2026-09-02 0:40 ` Sean Christopherson
2026-08-31 14:47 ` [PATCH v7 03/23] KVM: Allow KVM implementations to switch off MMIO independent of Kconfig Steffen Eiden
2026-09-02 0:38 ` Sean Christopherson [this message]
2026-08-31 14:47 ` [PATCH v7 04/23] arm64: Use proper include variant Steffen Eiden
2026-08-31 14:47 ` [PATCH v7 05/23] arm64: ptrace: Use constants for compat register numbers Steffen Eiden
2026-08-31 14:47 ` [PATCH v7 06/23] arm64: sysreg: Convert SPSR_ELx to automatic register generation Steffen Eiden
2026-08-31 14:47 ` [PATCH v7 07/23] KVM: arm64: Access elements of vcpu_gp_regs individually Steffen Eiden
2026-08-31 14:47 ` [PATCH v7 08/23] KVM: arm64: Use accessor functions for core regs Steffen Eiden
2026-08-31 14:47 ` [PATCH v7 09/23] arm64: Prepare sharing arm64 headers with s390 Steffen Eiden
2026-08-31 14:47 ` [PATCH v7 10/23] arm64: Share " Steffen Eiden
2026-08-31 14:47 ` [PATCH v7 11/23] KVM: arm64: Share arm64 code " Steffen Eiden
2026-09-01 8:13 ` Marc Zyngier
2026-09-01 8:40 ` Steffen Eiden
2026-08-31 14:47 ` [PATCH v7 12/23] s390/tools: Use arm64 headers Steffen Eiden
2026-08-31 14:47 ` [PATCH v7 13/23] KVM: s390: Use arm64 code Steffen Eiden
2026-08-31 14:47 ` [PATCH v7 14/23] KVM: s390: Prepare KVM/s390 for a second KVM module Steffen Eiden
2026-08-31 14:47 ` [PATCH v7 15/23] s390: Introduce Start Arm Execution instruction Steffen Eiden
2026-08-31 14:47 ` [PATCH v7 16/23] KVM: s390: arm64: Introduce host definitions Steffen Eiden
2026-08-31 14:47 ` [PATCH v7 17/23] s390/hwcaps: Report SAE support as hwcap Steffen Eiden
2026-08-31 14:47 ` [PATCH v7 18/23] KVM: s390: Add basic arm64 kvm module Steffen Eiden
2026-08-31 14:47 ` [PATCH v7 19/23] KVM: s390: arm64: Implement required functions Steffen Eiden
2026-08-31 14:47 ` [PATCH v7 20/23] KVM: s390: arm64: Implement vm/vcpu create destroy Steffen Eiden
2026-08-31 14:47 ` [PATCH v7 21/23] KVM: s390: arm64: Implement vCPU IOCTLs Steffen Eiden
2026-08-31 14:47 ` [PATCH v7 22/23] KVM: s390: arm64: Implement basic page fault handler Steffen Eiden
2026-08-31 14:48 ` [PATCH v7 23/23] KVM: s390: arm64: Add KVM_S390_ARM64 Kconfig and Makefile Steffen Eiden
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