Messages in this thread | | | Date | Thu, 29 Oct 2015 11:29:17 +0800 | From | ethan zhao <> | Subject | Re: [PATCH v2] iov: restore NumVFs register to 0 before return from virtfn_max_buses() |
| |
Alex, On 2015/10/27 23:15, Alexander Duyck wrote: > On 10/27/2015 02:28 AM, ethan zhao wrote: >> 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@oracle.com> >>>>> Tested-by: Sriharsha Yadagudde <sriharsha.devdas@oracle.com> >>>> 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@google.com> >>>> 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@oracle.com> >>>> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> >>>> >>>> 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 ? > > Because pci_iov_set_numvfs will end up resetting offset and stride > based on the values when it writes the 0 into numvfs. As such
Seems virtfn_max_buses() never call pci_iov_set_numvfs() with 0, so no need to check it before the last resetting to 0 ? > testing it after the reset could give you invalid values since offset > and stride can be 0 when numvfs is 0. > > Actually maybe I will go over this and submit a couple patches > myself. Looking over things it seems like the code has gotten a bit > silly since virtfn_max_busses looks like it is iterating over VFs and > that doesn't make much sense when offset and stride are both positive so far it works at least. :>
Thanks, Ethan > values so it should just be a matter of computing the bus of the last VF. > > - Alex
| |