From f6b30c1984f7db16aa971d7f300e2191e5b730b6 Mon Sep 17 00:00:00 2001 From: Alex Williamson Date: Thu, 8 Jun 2023 12:05:07 -0600 Subject: [PATCH] hw/vfio/pci-quirks: Support alternate offset for GPUDirect Cliques MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit NVIDIA Turing and newer GPUs implement the MSI-X capability at the offset previously reserved for use by hypervisors to implement the GPUDirect Cliques capability. A revised specification provides an alternate location. Add a config space walk to the quirk to check for conflicts, allowing us to fall back to the new location or generate an error at the quirk setup rather than when the real conflicting capability is added should there be no available location. Signed-off-by: Alex Williamson Reviewed-by: Cédric Le Goater Signed-off-by: Cédric Le Goater --- hw/vfio/pci-quirks.c | 41 ++++++++++++++++++++++++++++++++++++++++- 1 file changed, 40 insertions(+), 1 deletion(-) diff --git a/hw/vfio/pci-quirks.c b/hw/vfio/pci-quirks.c index f0147a050a..0ed2fcd531 100644 --- a/hw/vfio/pci-quirks.c +++ b/hw/vfio/pci-quirks.c @@ -1490,6 +1490,9 @@ void vfio_setup_resetfn_quirk(VFIOPCIDevice *vdev) * +---------------------------------+---------------------------------+ * * https://lists.gnu.org/archive/html/qemu-devel/2017-08/pdfUda5iEpgOS.pdf + * + * Specification for Turning and later GPU architectures: + * https://lists.gnu.org/archive/html/qemu-devel/2023-06/pdf142OR4O4c2.pdf */ static void get_nv_gpudirect_clique_id(Object *obj, Visitor *v, const char *name, void *opaque, @@ -1530,7 +1533,9 @@ const PropertyInfo qdev_prop_nv_gpudirect_clique = { static int vfio_add_nv_gpudirect_cap(VFIOPCIDevice *vdev, Error **errp) { PCIDevice *pdev = &vdev->pdev; - int ret, pos = 0xC8; + int ret, pos; + bool c8_conflict = false, d4_conflict = false; + uint8_t tmp; if (vdev->nv_gpudirect_clique == 0xFF) { return 0; @@ -1547,6 +1552,40 @@ static int vfio_add_nv_gpudirect_cap(VFIOPCIDevice *vdev, Error **errp) return -EINVAL; } + /* + * Per the updated specification above, it's recommended to use offset + * D4h for Turing and later GPU architectures due to a conflict of the + * MSI-X capability at C8h. We don't know how to determine the GPU + * architecture, instead we walk the capability chain to mark conflicts + * and choose one or error based on the result. + * + * NB. Cap list head in pdev->config is already cleared, read from device. + */ + ret = pread(vdev->vbasedev.fd, &tmp, 1, + vdev->config_offset + PCI_CAPABILITY_LIST); + if (ret != 1 || !tmp) { + error_setg(errp, "NVIDIA GPUDirect Clique ID: error getting cap list"); + return -EINVAL; + } + + do { + if (tmp == 0xC8) { + c8_conflict = true; + } else if (tmp == 0xD4) { + d4_conflict = true; + } + tmp = pdev->config[tmp + PCI_CAP_LIST_NEXT]; + } while (tmp); + + if (!c8_conflict) { + pos = 0xC8; + } else if (!d4_conflict) { + pos = 0xD4; + } else { + error_setg(errp, "NVIDIA GPUDirect Clique ID: invalid config space"); + return -EINVAL; + } + ret = pci_add_capability(pdev, PCI_CAP_ID_VNDR, pos, 8, errp); if (ret < 0) { error_prepend(errp, "Failed to add NVIDIA GPUDirect cap: "); -- 2.11.4.GIT