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Sat, 12 Sep 2026 11:43:29 +0000 Date: Sat, 12 Sep 2026 12:43:28 +0100 Message-ID: <86ecey7l0f.wl-maz@kernel.org> From: Marc Zyngier 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 , Nico Boehr , Nina Schoetterl-Glausch , Oliver Upton , Paolo Bonzini , Sean Christopherson , Suzuki K Poulose , Sven Schnelle , Ulrich Weigand , Vasily Gorbik , Will Deacon , Zenghui Yu Subject: Re: [PATCH v7 11/23] KVM: arm64: Share arm64 code with s390 In-Reply-To: <20260902124152.438647-C-seiden@linux.ibm.com> References: <20260831144802.834315-1-seiden@linux.ibm.com> <20260831144802.834315-12-seiden@linux.ibm.com> <87se3tmlrv.wl-maz@kernel.org> <20260901084037.185345-C-seiden@linux.ibm.com> <87mru0m76g.wl-maz@kernel.org> <20260902124152.438647-C-seiden@linux.ibm.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/30.1 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: seiden@linux.ibm.com, kvm@vger.kernel.org, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, agordeev@linux.ibm.com, gra@linux.ibm.com, arnd@arndb.de, catalin.marinas@arm.com, borntraeger@linux.ibm.com, imbrenda@linux.ibm.com, david@kernel.org, fritz@linux.ibm.com, tabba@google.com, ggala@linux.ibm.com, hari55@linux.ibm.com, hca@linux.ibm.com, brueckner@linux.ibm.com, iii@linux.ibm.com, frankja@linux.ibm.com, joey.gouly@arm.com, nrb@linux.ibm.com, oss@nina.schoetterlglausch.eu, oupton@kernel.org, pbonzini@redhat.com, seanjc@google.com, suzuki.poulose@arm.com, svens@linux.ibm.com, Ulrich.Weigand@de.ibm.com, gor@linux.ibm.com, will@kernel.org, yuzenghui@huawei.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false On Wed, 02 Sep 2026 13:41:52 +0100, Steffen Eiden wrote: [...] > So my suggestion is: > > For series 1 (and 2) s390 has its own, local implementation of > handle_exit without sharing any code with arm64 in regard to EC > > When s390 has all the relevant code available (likely series 3) s390 can > switch to using most (if not all) EC handling code used by > arm_exit_handlers implemented in handle_exit.c. > > This can be done without a mixed patch: > > 1. Mark arm64 handle_exit.c as shared (roughly the first 400Loc w/o > includes) - s390 will not use it after this patch. > 2. remove the handle exit code from s390's handle_exit.c and include the > new generated handle_exit.inc > > This approach brings us further into the share architecture not only code > approach you meantrioned in the comments regarding sys-regs. (I or > Andreas will provide a solution for this later :) ) > > Is that OK with you, what do you think? I *think* that's OK. I just want to make sure that in the long run, we don't end-up with pointless divergence. Thanks, M. -- Without deviation from the norm, progress is not possible.