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[34.105.23.239]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2adfb6b974csm34254135ad.65.2026.02.26.16.51.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 26 Feb 2026 16:51:22 -0800 (PST) Date: Fri, 27 Feb 2026 00:51:18 +0000 From: David Matlack To: Alex Williamson Cc: 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 10/22] vfio/pci: Skip reset of preserved device after Live Update Message-ID: References: <20260129212510.967611-1-dmatlack@google.com> <20260129212510.967611-11-dmatlack@google.com> <20260226170030.5a938c74@shazbot.org> Precedence: bulk X-Mailing-List: kvm@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: <20260226170030.5a938c74@shazbot.org> On 2026-02-26 05:00 PM, Alex Williamson wrote: > On Thu, 29 Jan 2026 21:24:57 +0000 > David Matlack wrote: > > - /* If reset fails because of the device lock, fail this path entirely */ > > - ret = pci_try_reset_function(pdev); > > - if (ret == -EAGAIN) > > - goto out_disable_device; > > + if (vdev->liveupdate_incoming_state) { > > + /* > > + * This device was preserved by the previous kernel across a > > + * Live Update, so it does not need to be reset. > > + */ > > + vdev->reset_works = vdev->liveupdate_incoming_state->reset_works; > > + } else { > > + /* > > + * If reset fails because of the device lock, fail this path > > + * entirely. > > + */ > > + ret = pci_try_reset_function(pdev); > > + if (ret == -EAGAIN) > > + goto out_disable_device; > > + > > + vdev->reset_works = !ret; > > + } > > This could maybe be incrementally cleaner in a > int vfio_pci_core_probe_reset(struct vfio_pci_core_device *vdev) > helper. Will do. > > > > - vdev->reset_works = !ret; > > pci_save_state(pdev); > > vdev->pci_saved_state = pci_store_saved_state(pdev); > > Isn't this a problem too? In the first kernel we store the initial, > post reset state of the device, now we're storing some arbitrary state. > This is the state we're restore when the device is closed. The previous kernel resets the device and restores it back to its post reset state in vfio_pci_liveupdate_freeze() before handing off control to the next kernel. So my intention here is that VFIO will receive the device in that state, allowing it to call pci_store_saved_state() here to capture the post reset state of the device again. Eventually we want to drop the reset in vfio_pci_liveupdate_freeze() and preserve vdev->pci_saved_state across the Live Update. But I was hoping to add that in a follow up series to avoid this one getting too long. > > diff --git a/include/linux/vfio_pci_core.h b/include/linux/vfio_pci_core.h > > index 350c30f84a13..95835298e29e 100644 > > --- a/include/linux/vfio_pci_core.h > > +++ b/include/linux/vfio_pci_core.h > > @@ -16,6 +16,7 @@ > > #include > > #include > > #include > > +#include > > > > #ifndef VFIO_PCI_CORE_H > > #define VFIO_PCI_CORE_H > > Wouldn't a forward declaration do, and the kho/abi include can be kept > out of the public header? Also should be in the previous patch? Will do.