On Thu, 13 Aug 2026 15:06:19 +0530 <[email protected]> wrote: > From: Manish Honap <[email protected]> > > Volatile CXL register state must be sampled from live hardware when the > guest opens the device, not at bind, because a low-power transition > between bind and open can leave bind-time values stale.
But patch 7 prevented such transitions, without really an explanation why. Accounting for being in full power state at open here further diminishes the requirement to restrict idle lower power states in that patch. > Add open_device and close_device to the CXL ops and call them from the > common enable and close paths. A failed open unwinds the enable like any > other error. The callbacks are stubs here and are filled in next. > > Signed-off-by: Manish Honap <[email protected]> > --- > drivers/vfio/pci/cxl/vfio_cxl_core.c | 11 +++++++ > drivers/vfio/pci/vfio_pci_core.c | 44 ++++++++++++++++++++++------ > include/linux/vfio_pci_core.h | 2 ++ > 3 files changed, 48 insertions(+), 9 deletions(-) > > diff --git a/drivers/vfio/pci/cxl/vfio_cxl_core.c > b/drivers/vfio/pci/cxl/vfio_cxl_core.c > index 966b7c22a6ac..d19fd638f538 100644 > --- a/drivers/vfio/pci/cxl/vfio_cxl_core.c > +++ b/drivers/vfio/pci/cxl/vfio_cxl_core.c > @@ -100,9 +100,20 @@ static void vfio_cxl_release_device(struct > vfio_pci_core_device *vdev) > vdev->cxl = NULL; > } > > +static int vfio_cxl_open_device(struct vfio_pci_core_device *vdev) > +{ > + return 0; > +} > + > +static void vfio_cxl_close_device(struct vfio_pci_core_device *vdev) > +{ > +} > + > static const struct vfio_cxl_ops vfio_cxl_ops = { > .init_device = vfio_cxl_init_device, > .release_device = vfio_cxl_release_device, > + .open_device = vfio_cxl_open_device, > + .close_device = vfio_cxl_close_device, > .owner = THIS_MODULE, > }; > > diff --git a/drivers/vfio/pci/vfio_pci_core.c > b/drivers/vfio/pci/vfio_pci_core.c > index 49dfbdaf3f05..470730cdc88b 100644 > --- a/drivers/vfio/pci/vfio_pci_core.c > +++ b/drivers/vfio/pci/vfio_pci_core.c > @@ -584,6 +584,21 @@ static const struct dev_pm_ops vfio_pci_core_pm_ops = { > NULL) > }; > > +static void vfio_pci_core_unmap_bars(struct vfio_pci_core_device *vdev) > +{ > + struct pci_dev *pdev = vdev->pdev; > + int i, bar; > + > + for (i = 0; i < PCI_STD_NUM_BARS; i++) { > + bar = i + PCI_STD_RESOURCES; > + if (IS_ERR_OR_NULL(vdev->barmap[bar])) > + continue; > + pci_iounmap(pdev, vdev->barmap[bar]); > + pci_release_selected_regions(pdev, 1 << bar); > + vdev->barmap[bar] = NULL; > + } > +} > + > int vfio_pci_core_enable(struct vfio_pci_core_device *vdev) > { > struct pci_dev *pdev = vdev->pdev; > @@ -660,8 +675,23 @@ int vfio_pci_core_enable(struct vfio_pci_core_device > *vdev) > > vfio_pci_core_map_bars(vdev); > > + if (vdev->cxl_ops) { > + ret = vdev->cxl_ops->open_device(vdev); > + if (ret) > + goto out_free_config; > + } > + > return 0; > > +out_free_config: > + /* > + * open_device() runs after vfio_config_init() and map_bars() have > + * succeeded, but a failed first open never reaches > vfio_pci_core_disable(). > + * Unwind the common vconfig and BAR state here so the allocations and > BAR > + * requests are not leaked for a later open to overwrite. > + */ > + vfio_config_free(vdev); > + vfio_pci_core_unmap_bars(vdev); Unwind in the reverse order, this should start with unmap bars. The above comment is rather gratuitous and looks a bit like AI slop. Thanks, Alex > out_free_zdev: > vfio_pci_zdev_close_device(vdev); > out_free_state: > @@ -682,7 +712,7 @@ void vfio_pci_core_disable(struct vfio_pci_core_device > *vdev) > struct pci_dev *pdev = vdev->pdev; > struct vfio_pci_dummy_resource *dummy_res, *tmp; > struct vfio_pci_ioeventfd *ioeventfd, *ioeventfd_tmp; > - int i, bar; > + int i; > > /* For needs_reset */ > lockdep_assert_held(&vdev->vdev.dev_set->lock); > @@ -737,14 +767,7 @@ void vfio_pci_core_disable(struct vfio_pci_core_device > *vdev) > > vfio_config_free(vdev); > > - for (i = 0; i < PCI_STD_NUM_BARS; i++) { > - bar = i + PCI_STD_RESOURCES; > - if (IS_ERR_OR_NULL(vdev->barmap[bar])) > - continue; > - pci_iounmap(pdev, vdev->barmap[bar]); > - pci_release_selected_regions(pdev, 1 << bar); > - vdev->barmap[bar] = NULL; > - } > + vfio_pci_core_unmap_bars(vdev); > > list_for_each_entry_safe(dummy_res, tmp, > &vdev->dummy_resources_list, res_next) { > @@ -827,6 +850,9 @@ void vfio_pci_core_close_device(struct vfio_device > *core_vdev) > #endif > vfio_pci_dma_buf_cleanup(vdev); > > + if (vdev->cxl_ops) > + vdev->cxl_ops->close_device(vdev); > + > vfio_pci_core_disable(vdev); > > mutex_lock(&vdev->igate); > diff --git a/include/linux/vfio_pci_core.h b/include/linux/vfio_pci_core.h > index 43755b91880f..7354dae1dd85 100644 > --- a/include/linux/vfio_pci_core.h > +++ b/include/linux/vfio_pci_core.h > @@ -70,6 +70,8 @@ struct vfio_pci_device_ops { > struct vfio_cxl_ops { > int (*init_device)(struct vfio_pci_core_device *vdev); > void (*release_device)(struct vfio_pci_core_device *vdev); > + int (*open_device)(struct vfio_pci_core_device *vdev); > + void (*close_device)(struct vfio_pci_core_device *vdev); > /* Pinned per bound CXL device so vfio-cxl cannot unload under usage */ > struct module *owner; > };
