From: Manish Honap <[email protected]> A CXL device needs the vfio-cxl callbacks, but pulling vfio-cxl and the CXL core in unconditionally would bloat every vfio-pci setup. At bind, detect a CXL device with pcie_is_cxl() and request_module("vfio-cxl") only then, and hand the device to the registered ops.
Each bound CXL device pins vfio-cxl through try_module_get() and drops the reference at release, so vfio-cxl can unload once no CXL device is bound. If vfio-cxl is absent the device is driven as plain vfio-pci. Signed-off-by: Manish Honap <[email protected]> --- drivers/vfio/pci/vfio_pci_core.c | 81 ++++++++++++++++++++++++++++++-- include/linux/vfio_pci_core.h | 3 ++ 2 files changed, 81 insertions(+), 3 deletions(-) diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c index 88e68d43af9a..0f9b5dfeea66 100644 --- a/drivers/vfio/pci/vfio_pci_core.c +++ b/drivers/vfio/pci/vfio_pci_core.c @@ -2176,6 +2176,44 @@ static void vfio_pci_vga_uninit(struct vfio_pci_core_device *vdev) VGA_RSRC_LEGACY_MEM); } +static const struct vfio_cxl_ops *vfio_pci_cxl_ops; +static DEFINE_MUTEX(vfio_pci_cxl_ops_lock); + +static const struct vfio_cxl_ops *vfio_pci_get_cxl_ops(void) +{ + const struct vfio_cxl_ops *ops; + + mutex_lock(&vfio_pci_cxl_ops_lock); + ops = vfio_pci_cxl_ops; + if (ops && !try_module_get(ops->owner)) + ops = NULL; + mutex_unlock(&vfio_pci_cxl_ops_lock); + + return ops; +} + +/* + * A CXL Type-2 device advertises both CXL.cache and CXL.mem in its CXL DVSEC. + * pcie_is_cxl() is also true for Type-1 (cache only) and Type-3 (mem only) + * devices, which the vfio-cxl provider does not handle, so confirm the Type-2 + * identity before engaging it. + */ +static bool vfio_pci_is_cxl_type2(struct pci_dev *pdev) +{ + u16 dvsec, cap; + + dvsec = pci_find_dvsec_capability(pdev, PCI_VENDOR_ID_CXL, + PCI_DVSEC_CXL_DEVICE); + if (!dvsec) + return false; + + if (pci_read_config_word(pdev, dvsec + PCI_DVSEC_CXL_CAP, &cap)) + return false; + + return (cap & PCI_DVSEC_CXL_CACHE_CAPABLE) && + (cap & PCI_DVSEC_CXL_MEM_CAPABLE); +} + int vfio_pci_core_init_dev(struct vfio_device *core_vdev) { struct vfio_pci_core_device *vdev = @@ -2197,6 +2235,41 @@ int vfio_pci_core_init_dev(struct vfio_device *core_vdev) init_rwsem(&vdev->memory_lock); xa_init(&vdev->ctx); + /* + * Load vfio-cxl on demand for a CXL device. If it is absent, drive the + * device as plain vfio-pci rather than failing the bind. + */ + if (pcie_is_cxl(vdev->pdev) && vfio_pci_is_cxl_type2(vdev->pdev)) { + const struct vfio_cxl_ops *ops; + + request_module("vfio-cxl"); + ops = vfio_pci_get_cxl_ops(); + if (ops) { + ret = ops->init_device(vdev); + if (ret) { + module_put(ops->owner); + return ret; + } + vdev->cxl_ops = ops; + /* + * Pin the device in D0 while bound rather than let + * the host power it down between opens. + */ + vdev->disable_idle_d3 = true; + } else if (IS_BUILTIN(CONFIG_VFIO_CXL)) { + /* + * Only DEFER for a built-in provider so the bind + * retries once vfio-cxl registers its ops. + * A modular provider was already loaded synchronously + * by request_module() above, so if it is still absent + * it is missing, blocked, or failed to init; drive the + * device as plain vfio-pci then rather than defer the + * bind forever. + */ + return -EPROBE_DEFER; + } + } + return 0; } EXPORT_SYMBOL_GPL(vfio_pci_core_init_dev); @@ -2206,6 +2279,11 @@ void vfio_pci_core_release_dev(struct vfio_device *core_vdev) struct vfio_pci_core_device *vdev = container_of(core_vdev, struct vfio_pci_core_device, vdev); + if (vdev->cxl_ops) { + vdev->cxl_ops->release_device(vdev); + module_put(vdev->cxl_ops->owner); + } + mutex_destroy(&vdev->igate); mutex_destroy(&vdev->ioeventfds_lock); kfree(vdev->region); @@ -2670,9 +2748,6 @@ static void vfio_pci_dev_set_try_reset(struct vfio_device_set *dev_set) } } -static const struct vfio_cxl_ops *vfio_pci_cxl_ops; -static DEFINE_MUTEX(vfio_pci_cxl_ops_lock); - int vfio_pci_core_register_cxl_ops(const struct vfio_cxl_ops *ops) { int ret = 0; diff --git a/include/linux/vfio_pci_core.h b/include/linux/vfio_pci_core.h index 14753972e714..117cd67995d8 100644 --- a/include/linux/vfio_pci_core.h +++ b/include/linux/vfio_pci_core.h @@ -29,6 +29,7 @@ struct vfio_pci_core_device; struct vfio_pci_region; struct p2pdma_provider; struct dma_buf_attachment; +struct vfio_cxl_state; struct vfio_pci_eventfd { struct eventfd_ctx *ctx; @@ -109,6 +110,8 @@ struct vfio_pci_core_device { struct vfio_device vdev; struct pci_dev *pdev; const struct vfio_pci_device_ops *pci_ops; + const struct vfio_cxl_ops *cxl_ops; + struct vfio_cxl_state *cxl; void __iomem *barmap[PCI_STD_NUM_BARS]; bool bar_mmap_supported[PCI_STD_NUM_BARS]; /* Flags modified at runtime - dedicated storage unit */ -- 2.25.1
