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Wed, 23 Sep 2026 08:58:36 -0700 (PDT) Received: from ziepe.ca ([130.41.10.202]) by smtp.gmail.com with ESMTPSA id 00721157ae682-8a4658c72f3sm11900977b3.17.2026.09.23.08.58.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 23 Sep 2026 08:58:36 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1x9PMg-0000000DwaY-36Ny; Wed, 23 Sep 2026 12:58:34 -0300 Date: Wed, 23 Sep 2026 12:58:34 -0300 From: Jason Gunthorpe To: "Aneesh Kumar K.V" Cc: Catalin Marinas , linux-coco@lists.linux.dev, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, iommu@lists.linux.dev, Marc Zyngier , Marek Szyprowski , Robin Murphy , Steven Price , Suzuki K Poulose , Thomas Gleixner , Will Deacon Subject: Re: [PATCH v6 0/9] coco: guest: Enforce host page-size alignment for shared buffers Message-ID: <20260923155834.GK1540250@ziepe.ca> References: <20260904103452.1197239-1-aneesh.kumar@kernel.org> <20260918165754.GG11599@ziepe.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260923_085837_883925_5EB1F403 X-CRM114-Status: GOOD ( 14.22 ) 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Sep 23, 2026 at 10:31:19AM +0530, Aneesh Kumar K.V wrote: > Jason Gunthorpe writes: > > > On Fri, Sep 18, 2026 at 05:52:31PM +0100, Catalin Marinas wrote: > > > >> TBH, I'm tempted not to support this configuration at all, just fail > >> gracefully if the realm page size doesn't match the host's. However, if > >> that's a real world configuration, > > > > realm != host is going to be fairly common. > > > > host > realm is probably not that common, I would guess. > > Wouldn't it be more common to run a distro with a 4K page size as the > guest on a custom hypervisor with a 4K or larger page size? Maybe someday, but right now I think the 4k hyp is going to be common and people who really reach for 16/64k are going to need to run !4k guests too. Jason