Re: [PATCH v2] iov: restore NumVFs register to 0 before return from virtfn_max_buses()
From: ethan zhao
Date: Tue Oct 27 2015 - 05:29:05 EST
Alexander,
On 2015/10/27 13:48, Alexander Duyck wrote:
On 10/15/2015 10:16 AM, Bjorn Helgaas wrote:
Hi Ethan,
On Wed, Sep 16, 2015 at 12:19:53PM +0900, Ethan Zhao wrote:
After commit 4449f079722c ("PCI: Calculate maximum number of buses
required for VFs"),the initial value of NumVFs register was left to
non-zero after sriov_init() and no VFs was enabled in device driver.
this changed the behaviour of kernel exported by lspci and sysfs etc.
so this patch restore the NumVFs register to zero after the
calculation of max_VF_buses was done and before return from
virtfn_max_buses().
Tested on stable 4.1 and passed building on stable 4.3-rc1
Signed-off-by: Ethan Zhao <ethan.zhao@xxxxxxxxxx>
Tested-by: Sriharsha Yadagudde <sriharsha.devdas@xxxxxxxxxx>
Can you test the patch below? I'm trying to avoid touching
PCI_SRIOV_NUM_VF in more than one place, and I think it's OK to set it
and test offset/stride at the end, instead of setting NUM_VF to zero,
testing offset/stride, computing max_bus, then setting NUM_VF to zero
again.
Bjorn
commit 8e20e89658f23b8d16b1e21810e9f63c8625129c
Author: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Date: Thu Oct 15 11:31:21 2015 -0500
PCI: Set SR-IOV NumVFs to zero after enumeration
The enumeration path should leave NumVFs set to zero. But
after
4449f079722c ("PCI: Calculate maximum number of buses required
for VFs"),
we call virtfn_max_buses() in the enumeration path, which
changes NumVFs.
This NumVFs change is visible via lspci and sysfs until a driver
enables
SR-IOV.
Set NumVFs to zero after virtfn_max_buses() computes the
maximum number of
buses.
Fixes: 4449f079722c ("PCI: Calculate maximum number of
buses required for VFs")
Based-on-patch-by: Ethan Zhao <ethan.zhao@xxxxxxxxxx>
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index ee0ebff..0202ab0 100644
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -384,7 +384,7 @@ static int sriov_init(struct pci_dev *dev, int pos)
int rc;
int nres;
u32 pgsz;
- u16 ctrl, total, offset, stride;
+ u16 ctrl, total;
struct pci_sriov *iov;
struct resource *res;
struct pci_dev *pdev;
@@ -414,11 +414,6 @@ static int sriov_init(struct pci_dev *dev, int pos)
found:
pci_write_config_word(dev, pos + PCI_SRIOV_CTRL, ctrl);
- pci_write_config_word(dev, pos + PCI_SRIOV_NUM_VF, 0);
- pci_read_config_word(dev, pos + PCI_SRIOV_VF_OFFSET, &offset);
- pci_read_config_word(dev, pos + PCI_SRIOV_VF_STRIDE, &stride);
- if (!offset || (total > 1 && !stride))
- return -EIO;
pci_read_config_dword(dev, pos + PCI_SRIOV_SUP_PGSIZE, &pgsz);
i = PAGE_SHIFT > 12 ? PAGE_SHIFT - 12 : 0;
@@ -456,8 +451,6 @@ found:
iov->nres = nres;
iov->ctrl = ctrl;
iov->total_VFs = total;
- iov->offset = offset;
- iov->stride = stride;
iov->pgsz = pgsz;
iov->self = dev;
pci_read_config_dword(dev, pos + PCI_SRIOV_CAP, &iov->cap);
@@ -475,6 +468,11 @@ found:
dev->sriov = iov;
dev->is_physfn = 1;
iov->max_VF_buses = virtfn_max_buses(dev);
+ pci_iov_set_numvfs(dev, 0);
+ if (!iov->offset || (total > 1 && !iov->stride)) {
+ rc = -EIO;
+ goto failed;
+ }
return 0;
You might want to reorder this a bit. The problem is offset and
stride can be 0 if numvfs is 0. So you should probably test offset
and stride
Yes, the spec says "Note: First VF Offset is unused if NumVFs is 0. If
NumVFs is greater than 0, First VF Offset must
25 not be zero. "
first, and then reset numvfs to 0.
Why test it before reset numvfs ?
Thanks,
Ethan
- Alex
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