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[34.105.23.239]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-82739ff37f1sm347240b3a.40.2026.02.25.15.20.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Feb 2026 15:20:14 -0800 (PST) Date: Wed, 25 Feb 2026 23:20:10 +0000 From: David Matlack To: Bjorn Helgaas Cc: Alex Williamson , Adithya Jayachandran , Alexander Graf , Alex Mastro , Alistair Popple , Andrew Morton , Ankit Agrawal , Bjorn Helgaas , Chris Li , David Rientjes , Jacob Pan , Jason Gunthorpe , Jason Gunthorpe , Jonathan Corbet , Josh Hilke , Kevin Tian , kexec@lists.infradead.org, kvm@vger.kernel.org, Leon Romanovsky , Leon Romanovsky , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, linux-pci@vger.kernel.org, Lukas Wunner , =?utf-8?Q?Micha=C5=82?= Winiarski , Mike Rapoport , Parav Pandit , Pasha Tatashin , Pranjal Shrivastava , Pratyush Yadav , Raghavendra Rao Ananta , Rodrigo Vivi , Saeed Mahameed , Samiullah Khawaja , Shuah Khan , Thomas =?iso-8859-1?Q?Hellstr=F6m?= , Tomita Moeko , Vipin Sharma , Vivek Kasireddy , William Tu , Yi Liu , Zhu Yanjun Subject: Re: [PATCH v2 03/22] PCI: Inherit bus numbers from previous kernel during Live Update Message-ID: References: <20260129212510.967611-4-dmatlack@google.com> <20260225224746.GA3714478@bhelgaas> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260225224746.GA3714478@bhelgaas> On 2026-02-25 04:47 PM, Bjorn Helgaas wrote: > On Thu, Jan 29, 2026 at 09:24:50PM +0000, David Matlack wrote: > > Inherit bus numbers from the previous kernel during a Live Update when > > one or more PCI devices are being preserved. This is necessary so that > > preserved devices can DMA through the IOMMU during a Live Update > > (changing bus numbers would break IOMMU translation). > > I think changing bus numbers would break DMA regardless of whether an > IOMMU is involved. Completions carrying the data for DMA reads are > routed back to the Requester ID of the read. Ahh, makes sense. I'll clarify the commit message in the next version.