Hi, Alex,
Thanks very much for your quick review and I am sorry for my late
response.
On 09/10/2015 11:29 PM, Alex Williamson wrote:
On Thu, 2015-09-10 at 20:12 +0800, Cao jin wrote:
Enable PCI-e device multifunction hot, just ensure the function 0
added last, then driver will got the notification to scan all the
function in the slot.
Signed-off-by: Cao jin <caoj.f...@cn.fujitsu.com>
---
hw/pci/pcie.c | 22 +++++++++++++---------
1 file changed, 13 insertions(+), 9 deletions(-)
diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c
index 6e28985..61ebefd 100644
--- a/hw/pci/pcie.c
+++ b/hw/pci/pcie.c
@@ -249,16 +249,20 @@ void pcie_cap_slot_hotplug_cb(HotplugHandler
*hotplug_dev, DeviceState *dev,
return;
}
- /* TODO: multifunction hot-plug.
- * Right now, only a device of function = 0 is allowed to be
- * hot plugged/unplugged.
+ /* To enable multifunction hot-plug, we just ensure the function
+ * 0 added last. Until function 0 added, we set the sltsta and
+ * inform OS via event notification.
*/
- assert(PCI_FUNC(pci_dev->devfn) == 0);
-
- pci_word_test_and_set_mask(exp_cap + PCI_EXP_SLTSTA,
- PCI_EXP_SLTSTA_PDS);
- pcie_cap_slot_event(PCI_DEVICE(hotplug_dev),
- PCI_EXP_HP_EV_PDC | PCI_EXP_HP_EV_ABP);
+ if (!(pci_dev->cap_present & QEMU_PCI_CAP_MULTIFUNCTION) &&
+ PCI_FUNC(pci_dev->devfn) > 0) {
The PCI spec is actually not entirely clear about whether each function
in a multifunction device needs to have the multifunction bit set or if
only function 0 needs to set it. From a discovery perspective, a kernel
should only scan for function 0 and only scan non-zero funcions if
function 0 reports the multifunction bit set. Therefore, it doesn't
particularly matter what non-zero functions report for the multifunction
bit. QEMU allows either interpretation (see comment in
pci_init_multifunction), so this appears to be a new requirement that
breaks assumptions elsewhere. Thanks,
Alex
Yes, PCI Spec does not describe it clearly. The if() here, is based on
the condition like following:
(qemu) device_add e1000,bus=pb1,id=net1,addr=00.1
(qemu) device_add e1000,bus=pb1,id=net0,addr=00.0
PCI: 0.0 indicates single function, but 0.1 is already populated.
Now, we can see the net1 via "info pci" while can`t see net1 in guest
via "lspci -t", so I think maybe it is not good condition, but no big
deal, so I use the if() to prevent the condition.
will remove the if() in next version.
+ error_setg(errp, "single function device, function number must be 0,"
+ "but got %d", PCI_FUNC(pci_dev->devfn));
+ } else if (PCI_FUNC(pci_dev->devfn) == 0) {
+ pci_word_test_and_set_mask(exp_cap + PCI_EXP_SLTSTA,
+ PCI_EXP_SLTSTA_PDS);
+ pcie_cap_slot_event(PCI_DEVICE(hotplug_dev),
+ PCI_EXP_HP_EV_PDC | PCI_EXP_HP_EV_ABP);
+ }
}
void pcie_cap_slot_hot_unplug_request_cb(HotplugHandler *hotplug_dev,
.
--
Yours Sincerely,
Cao Jin
