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Tue, 09 Sep 2025 12:55:46 -0700 (PDT) Received: from [192.168.40.164] ([70.105.235.240]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-73a16bb3ff5sm74385076d6.1.2025.09.09.12.55.44 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 09 Sep 2025 12:55:45 -0700 (PDT) Message-ID: <25676d12-57f0-4f54-8554-a6d77d2c6631@redhat.com> Date: Tue, 9 Sep 2025 15:55:43 -0400 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 06/11] iommu: Compute iommu_groups properly for PCIe MFDs To: Jason Gunthorpe Cc: Bjorn Helgaas , iommu@lists.linux.dev, Joerg Roedel , linux-pci@vger.kernel.org, Robin Murphy , Will Deacon , Alex Williamson , Lu Baolu , galshalom@nvidia.com, Joerg Roedel , Kevin Tian , kvm@vger.kernel.org, maorg@nvidia.com, patches@lists.linux.dev, tdave@nvidia.com, Tony Zhu References: <6-v3-8827cc7fc4e0+23f-pcie_switch_groups_jgg@nvidia.com> <20250909133128.GK789684@nvidia.com> From: Donald Dutile In-Reply-To: <20250909133128.GK789684@nvidia.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: wiPj0XQpKMg4an2X8EATqWVJK3ZCE0ezyTNjYaD0Gc0_1757447746 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 9/9/25 9:31 AM, Jason Gunthorpe wrote: > On Tue, Sep 09, 2025 at 12:57:59AM -0400, Donald Dutile wrote: > >> ... and why was the above code done in patch 3 and then undone here to >> use the reachable() support in patch 5 below, when patch 5 could be moved before >> patch 3, and we just get to this final implementation, dropping (some of) patch 3? > > If you use that order then the switch stuff has to be done and redone :( > > I put it in this order because the switch change seems lower risk to > me. Fewer people have switches in their system. While the MFD change > on top is higher risk, even my simple consumer test systems hit > troubles with it. > In 'my world' I see -lots- of switches in servers. I don't disagree on the MFD being a higher risk, and more common across all systems. > Jason > poe-tay-toe, poh-tah-toh... It gets to the end point needed. Thanks for reasoning... Reviewed-by: Donald Dutile