On Tue, Jul 28, 2026 at 10:10:03PM +0000, David Matlack wrote: > Adopt the ARI Forwarding Enable bit on preserved bridges and update > pci_dev->ari_enabled accordingly during a Live Update. This ensures that > the preserved devices on the bridge's secondary bus can be identified > with the same expanded 8-bit function number after a Live Update. > > Signed-off-by: David Matlack <[email protected]>
Reviewed-by: Bjorn Helgaas <[email protected]> > --- > drivers/pci/liveupdate.c | 30 ++++++++++++++++++++++++++++++ > drivers/pci/liveupdate.h | 6 ++++++ > drivers/pci/pci.c | 8 +++++++- > 3 files changed, 43 insertions(+), 1 deletion(-) > > diff --git a/drivers/pci/liveupdate.c b/drivers/pci/liveupdate.c > index fb602dd3933e..744513ee11ed 100644 > --- a/drivers/pci/liveupdate.c > +++ b/drivers/pci/liveupdate.c > @@ -128,6 +128,10 @@ > * way after Live Update and ensures that IOMMU groups do not change. Note > * that a device will use its adopted ACS controls for the lifetime of its > * struct pci_dev (i.e. even after pci_liveupdate_finish()). > + * > + * * The PCI core adopts ARI Forwarding Enable on all bridges with > downstream > + * preserved devices to ensure that all preserved devices on the bridge's > + * secondary bus are addressable after the Live Update. > */ > > #define pr_fmt(fmt) "PCI: liveupdate: " fmt > @@ -833,6 +837,32 @@ int pci_liveupdate_enable_adopted_acs_controls(struct > pci_dev *dev) > return 0; > } > > +/** > + * pci_liveupdate_adopt_ari() - Adopt ARI configuration > + * @dev: The PCI device to adopt ARI configuration for > + * > + * For devices preserved across a Live Update, read the ARI state from > + * hardware and adopt it. This ensures the device continues to use the ARI > + * configuration established by the previous kernel. > + * > + * Return: 0 on success, or -EINVAL if the device was not preserved. > + */ > +int pci_liveupdate_adopt_ari(struct pci_dev *dev) > +{ > + u16 val; > + > + guard(rwsem_read)(&pci_liveupdate.rwsem); > + > + if (!dev->liveupdate.incoming) > + return -EINVAL; > + > + pcie_capability_read_word(dev, PCI_EXP_DEVCTL2, &val); > + > + /* Safe to modify dev->ari_enabled bitfield during enumeration. */ > + dev->ari_enabled = !!(val & PCI_EXP_DEVCTL2_ARI); > + return 0; > +} > + > /** > * pci_liveupdate_is_incoming() - Check if a device is incoming-preserved > * @dev: The PCI device to check > diff --git a/drivers/pci/liveupdate.h b/drivers/pci/liveupdate.h > index ac5b8bf2edf5..ccc23031e99d 100644 > --- a/drivers/pci/liveupdate.h > +++ b/drivers/pci/liveupdate.h > @@ -18,6 +18,7 @@ bool pci_liveupdate_preserve_bus_numbers(struct pci_bus > *bus, > void pci_liveupdate_scan_bridge_end(struct pci_dev *dev); > void pci_liveupdate_cache_adopted_acs_controls(struct pci_dev *dev); > int pci_liveupdate_enable_adopted_acs_controls(struct pci_dev *dev); > +int pci_liveupdate_adopt_ari(struct pci_dev *dev); > #else > static inline void pci_liveupdate_setup_device(struct pci_dev *dev) > { > @@ -45,6 +46,11 @@ static inline int > pci_liveupdate_enable_adopted_acs_controls(struct pci_dev *dev > { > return -EINVAL; > } > + > +static inline int pci_liveupdate_adopt_ari(struct pci_dev *dev) > +{ > + return -EINVAL; > +} > #endif > > #endif /* DRIVERS_PCI_LIVEUPDATE_H */ > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > index 22001bdf4c97..6922f361a89e 100644 > --- a/drivers/pci/pci.c > +++ b/drivers/pci/pci.c > @@ -3528,7 +3528,7 @@ void pci_configure_ari(struct pci_dev *dev) > u32 cap; > struct pci_dev *bridge; > > - if (pcie_ari_disabled || !pci_is_pcie(dev) || dev->devfn) > + if (!pci_is_pcie(dev) || dev->devfn) > return; > > bridge = dev->bus->self; > @@ -3539,6 +3539,12 @@ void pci_configure_ari(struct pci_dev *dev) > if (!(cap & PCI_EXP_DEVCAP2_ARI)) > return; > > + if (!pci_liveupdate_adopt_ari(bridge)) > + return; > + > + if (pcie_ari_disabled) > + return; > + > if (pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ARI)) { > pcie_capability_set_word(bridge, PCI_EXP_DEVCTL2, > PCI_EXP_DEVCTL2_ARI); > -- > 2.55.0.487.gaf234c4eb3-goog >
