From: Manish Honap <[email protected]> The guest drives a single virtual decoder whose memory maps 1:1, so a device with more than one HDM decoder, or an interleaved one, cannot be represented. Turn that assumption into an explicit refusal at bind rather than a silent misprogramming later.
Signed-off-by: Manish Honap <[email protected]> --- drivers/vfio/pci/cxl/vfio_cxl_core.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/drivers/vfio/pci/cxl/vfio_cxl_core.c b/drivers/vfio/pci/cxl/vfio_cxl_core.c index 125e11354a46..7edc53b25576 100644 --- a/drivers/vfio/pci/cxl/vfio_cxl_core.c +++ b/drivers/vfio/pci/cxl/vfio_cxl_core.c @@ -36,10 +36,30 @@ static int vfio_cxl_init_device(struct vfio_pci_core_device *vdev) if (!pdev->hdm) return -EPROBE_DEFER; + /* The guest drives one virtual decoder; multiple are unsupported. */ + if (pdev->hdm->decoder_count != 1) + return -EOPNOTSUPP; + hdm_size = range_len(&pdev->hdm->settings[0].hpa_range); if (!hdm_size) return -ENXIO; + /* Interleaved decoders are unsupported. */ + if (pdev->hdm->settings[0].interleave_ways != 1) + return -EOPNOTSUPP; + + /* + * The guest drives resets through the CXL Device DVSEC and polls the + * shadow for completion. If the host cannot service a function-scoped + * CXL reset (no reset DVSEC, a multifunction device, or no HDM reset + * support), that guest request could never complete, so refuse the + * device rather than advertise a reset the guest would poll on forever. + */ + if (!cxl_reset_capable(pdev)) { + pci_err(pdev, "vfio-cxl: Unsupported device: host cannot service a CXL reset request\n"); + return -EOPNOTSUPP; + } + dvsec = pci_find_dvsec_capability(pdev, PCI_VENDOR_ID_CXL, PCI_DVSEC_CXL_DEVICE); serial = pci_get_dsn(pdev); -- 2.25.1
