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[2003:f6:af0e:4d00:dda5:3016:e366:575f]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-46fdf0c7191sm62333371cf.21.2025.02.04.09.42.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 04 Feb 2025 09:42:10 -0800 (PST) Date: Tue, 4 Feb 2025 18:42:04 +0100 (CET) From: Sebastian Ott To: Marc Zyngier cc: Shameer Kolothum , kvmarm@lists.linux.dev, oliver.upton@linux.dev, catalin.marinas@arm.com, will@kernel.org, mark.rutland@arm.com, Cornelia Huck , eric.auger@redhat.com, yuzenghui@huawei.com, wangzhou1@hisilicon.com, jiangkunkun@huawei.com, jonathan.cameron@huawei.com, anthony.jebson@huawei.com, linux-arm-kernel@lists.infradead.org, linuxarm@huawei.com Subject: Re: [PATCH v5 0/4] KVM: arm64: Errata management for VM Live migration In-Reply-To: <8634gtvdmi.wl-maz@kernel.org> Message-ID: References: <20250124151732.6072-1-shameerali.kolothum.thodi@huawei.com> <76172c57-aac6-d540-5b98-8de100c0886c@redhat.com> <8634gtvdmi.wl-maz@kernel.org> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: BAaFXuuazNp8_mqN5z9AqVrCVnMgUlDwseBOw9H2Vl8_1738690931 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII; format=flowed On Tue, 4 Feb 2025, Marc Zyngier wrote: > On Tue, 04 Feb 2025 16:45:38 +0000, > Sebastian Ott wrote: >> >> Hey, >> >> On Fri, 24 Jan 2025, Shameer Kolothum wrote: >>> On ARM64 platforms most of the errata workarounds are based on CPU >>> MIDR/REVIDR values and a number of these workarounds need to be >>> implemented by the Guest kernel as well. This creates a problem when >>> Guest needs to be migrated to a platform that differs in these >>> MIDR/REVIDR values even if the VMM can come up with a common minimum >>> feature list for the Guest using the recently introduced "Writable >>> ID registers" support. >> >> Currently MIDR/REVIDR are still RO and guest access is not trapped - so >> even with the errata management patches in place the guest state would >> change and a migration (between hosts that differ in these regs) would >> not be possible. Are there any plans to allow to actually change these? > > Sure thing. We only need a victim! :) ;-) Nice. I'll hack smth up then. Sebastian