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From: Oliver Upton To: Marc Zyngier Cc: James Morse , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, Quentin Perret , Will Deacon , Reiji Watanabe , Suzuki K Poulose , Zenghui Yu Subject: Re: [PATCH 3/5] KVM: arm64: Only return attributes from stage2_update_leaf_attrs() Message-ID: References: <20230111000300.2034799-1-oliver.upton@linux.dev> <20230111000300.2034799-4-oliver.upton@linux.dev> <87ilhde9me.wl-maz@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Migadu-Flow: FLOW_OUT X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230202_140853_013808_28405600 X-CRM114-Status: GOOD ( 21.13 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Jan 11, 2023 at 05:21:13PM +0000, Oliver Upton wrote: > Hey Marc, > > On Wed, Jan 11, 2023 at 08:52:25AM +0000, Marc Zyngier wrote: > > [+ Suzuki and Zenghui who are missing from the Cc list] > > Doh! Just switched over to working out of a new git tree and didn't move > over my cc-cmd. Apologies to you two. > > > On Wed, 11 Jan 2023 00:02:58 +0000, > > Oliver Upton wrote: > > > > > > Returning a single PTE from stage2_update_leaf_attrs() doesn't make a > > > great deal of sense given that the function could be used to apply a > > > change to a range of PTEs. Instead, return a bitwise OR of attributes > > > from all the visited PTEs. > > > > I find this amalgamation of attributes quite confusing, and I have a > > hard time attaching semantics to the resulting collection of bits. > > > > It also means that you cannot reason about a particular attribute > > being 0 if any of the neighbour PTEs has this bit set. > > Very true. What I had really wanted to do was make a walker that allows > software to check the state of specific attribute bit(s) within a range > of memory instead of returning all of them. I decided against it because > it would put more churn on other callers or require a new walker > entirely. > > Anyway, I can go about that change to make this a bit easier to reason > about. Thoughts? LOL, I thought I hadn't replied which is why I didn't hear anything back. Ball is in your court, Marc, any thoughts? -- Thanks, Oliver _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel