Hi Volodymyr,
This patch was mentioned in another context about allocating the BDF. So
I thought I would comment here as well.
On 12/10/2023 23:09, Volodymyr Babchuk wrote:
From: Oleksandr Andrushchenko <oleksandr_andrushche...@epam.com>
Assign SBDF to the PCI devices being passed through with bus 0.
The resulting topology is where PCIe devices reside on the bus 0 of the
root complex itself (embedded endpoints).
This implementation is limited to 32 devices which are allowed on
a single PCI bus.
Please note, that at the moment only function 0 of a multifunction
device can be passed through.
Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushche...@epam.com>
Your signed-off-by should be added even if you are only sending the
patch on behalf of Oleksandr. This is part of the DCO [1]
diff --git a/xen/drivers/vpci/vpci.c b/xen/drivers/vpci/vpci.c
index 5e34d0092a..7c46a2d3f4 100644
--- a/xen/drivers/vpci/vpci.c
+++ b/xen/drivers/vpci/vpci.c
@@ -36,6 +36,52 @@ extern vpci_register_init_t *const __start_vpci_array[];
extern vpci_register_init_t *const __end_vpci_array[];
#define NUM_VPCI_INIT (__end_vpci_array - __start_vpci_array)
+#ifdef CONFIG_HAS_VPCI_GUEST_SUPPORT
+static int add_virtual_device(struct pci_dev *pdev)
+{
+ struct domain *d = pdev->domain;
+ unsigned long new_dev_number;
+
+ if ( is_hardware_domain(d) )
+ return 0;
+
+ ASSERT(rw_is_write_locked(&pdev->domain->pci_lock));
+
+ /*
+ * Each PCI bus supports 32 devices/slots at max or up to 256 when
+ * there are multi-function ones which are not yet supported.
+ */
+ if ( pdev->info.is_extfn && !pdev->info.is_virtfn )
+ {
+ gdprintk(XENLOG_ERR, "%pp: only function 0 passthrough supported\n",
+ &pdev->sbdf);
+ return -EOPNOTSUPP;
+ }
+ new_dev_number = find_first_zero_bit(d->vpci_dev_assigned_map,
+ VPCI_MAX_VIRT_DEV);
IIUC, this means that Xen will allocate the BDF. I think this will
become a problem quite quickly as some of the PCI may need to be
assigned at a specific vBDF (I have the intel graphic card in mind).
Also, xl allows you to specificy the slot (e.g. <bdf>@<vslot>) which
would not work with this approach.
For dom0less passthrough, I feel the virtual BDF should always be
specified in device-tree. When a domain is created after boot, then I
think you want to support <bdf>@<vslot> where <vslot> is optional.
[1] https://cert-manager.io/docs/contributing/sign-off/
--
Julien Grall
