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Wed, 11 Nov 2020 13:52:06 +0000 MIME-Version: 1.0 Date: Wed, 11 Nov 2020 13:52:06 +0000 From: Marc Zyngier To: David Brazdil Subject: Re: [PATCH v1 07/24] kvm: arm64: Create nVHE copy of cpu_logical_map In-Reply-To: <20201111134527.ygzf5cm6qpdpcroo@google.com> References: <20201109113233.9012-1-dbrazdil@google.com> <20201109113233.9012-8-dbrazdil@google.com> <20201111130321.qalrzfabdonrwvsz@google.com> <15a580e6ac06294ead8859fba8f51deb@kernel.org> <20201111134527.ygzf5cm6qpdpcroo@google.com> User-Agent: Roundcube Webmail/1.4.9 Message-ID: <3ed604d7837fa64ec7c4fe5920c57382@kernel.org> X-Sender: maz@kernel.org X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: dbrazdil@google.com, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com, catalin.marinas@arm.com, will@kernel.org, dennis@kernel.org, tj@kernel.org, cl@linux.com, mark.rutland@arm.com, lorenzo.pieralisi@arm.com, qperret@google.com, ascull@google.com, qwandor@google.com, kernel-team@android.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201111_085210_541932_E5408B31 X-CRM114-Status: GOOD ( 22.69 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , kernel-team@android.com, Lorenzo Pieralisi , Andrew Walbran , Suzuki K Poulose , Catalin Marinas , Quentin Perret , linux-kernel@vger.kernel.org, James Morse , linux-arm-kernel@lists.infradead.org, Tejun Heo , Dennis Zhou , Christoph Lameter , Will Deacon , kvmarm@lists.cs.columbia.edu, Julien Thierry , Andrew Scull Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2020-11-11 13:45, David Brazdil wrote: > On Wed, Nov 11, 2020 at 01:29:29PM +0000, Marc Zyngier wrote: >> On 2020-11-11 13:03, David Brazdil wrote: >> > > > +/* >> > > > + * nVHE copy of data structures tracking available CPU cores. >> > > > + * Only entries for CPUs that were online at KVM init are populated. >> > > > + * Other CPUs should not be allowed to boot because their features were >> > > > + * not checked against the finalized system capabilities. >> > > > + */ >> > > > +u64 __ro_after_init __cpu_logical_map[NR_CPUS] = { [0 ... NR_CPUS-1] >> > > > = INVALID_HWID }; >> > > >> > > I'm not sure what __ro_after_init means once we get S2 isolation. >> > >> > It is stretching the definition of 'init' a bit, I know, but I don't see >> > what >> > your worry is about S2? The intention is to mark this read-only for >> > .hyp.text >> > at runtime. With S2, the host won't be able to write to it after KVM >> > init. >> > Obviously that's currently not the case. >> >> More importantly, EL2 can write to it at any time, which is the bit >> I'm >> worried >> about, as it makes the annotation misleading. > > EL2 can't, at least not accidentally. The hyp memory mapping is > PAGE_HYP_RO > (see patch 05). Ah, I obviously overlooked that. Thanks for setting me straight. > Shouldn't clash with include files. Where fixing the kernel might clash > is > all the users of for_each_*_cpu that use an int for the iterator var. I don't think that's a problem (nobody expects that many CPUs). But if you are confident that we don't have a problem, no need to change the kernel itself. M. -- Jazz is not dead. It just smells funny... _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel