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Date: Fri, 30 Oct 2015 11:48:21 +0800
From: Wei Yang <weiyang@...ux.vnet.ibm.com>
To: Bjorn Helgaas <bhelgaas@...gle.com>
Cc: Alexander Duyck <aduyck@...antis.com>, linux-pci@...r.kernel.org,
Ethan Zhao <ethan.zhao@...cle.com>,
Wei Yang <weiyang@...ux.vnet.ibm.com>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/7] PCI: Set SR-IOV NumVFs to zero after enumeration
On Thu, Oct 29, 2015 at 05:22:54PM -0500, Bjorn Helgaas wrote:
>ines: 115
>
>From: Alexander Duyck <aduyck@...antis.com>
>
>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.
>
>Iterate from TotalVFs down to zero so NumVFs is zero when we're finished
>computing the maximum number of buses. Validate offset and stride in
>the loop, so we can test it at every possible NumVFs setting. Rename
>virtfn_max_buses() to compute_max_vf_buses() to hint that it does have a
>side effect of updating iov->max_VF_buses.
>
>[bhelgaas: changelog, rename, allow numVF==1 && stride==0, rework loop,
>reverse sense of error path]
>Fixes: 4449f079722c ("PCI: Calculate maximum number of buses required for VFs")
>Based-on-patch-by: Ethan Zhao <ethan.zhao@...cle.com>
>Signed-off-by: Alexander Duyck <aduyck@...antis.com>
>Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
>---
> drivers/pci/iov.c | 41 ++++++++++++++++++++++-------------------
> 1 file changed, 22 insertions(+), 19 deletions(-)
>
>diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
>index 0cdb2d1..1b1acc2 100644
>--- a/drivers/pci/iov.c
>+++ b/drivers/pci/iov.c
>@@ -54,24 +54,29 @@ static inline void pci_iov_set_numvfs(struct pci_dev *dev, int nr_virtfn)
> * The PF consumes one bus number. NumVFs, First VF Offset, and VF Stride
> * determine how many additional bus numbers will be consumed by VFs.
> *
>- * Iterate over all valid NumVFs and calculate the maximum number of bus
>- * numbers that could ever be required.
>+ * Iterate over all valid NumVFs, validate offset and stride, and calculate
>+ * the maximum number of bus numbers that could ever be required.
> */
>-static inline u8 virtfn_max_buses(struct pci_dev *dev)
>+static int compute_max_vf_buses(struct pci_dev *dev)
> {
> struct pci_sriov *iov = dev->sriov;
>- int nr_virtfn;
>- u8 max = 0;
>- int busnr;
>+ int nr_virtfn, busnr, rc = 0;
>
>- for (nr_virtfn = 1; nr_virtfn <= iov->total_VFs; nr_virtfn++) {
>+ for (nr_virtfn = iov->total_VFs; nr_virtfn; nr_virtfn--) {
Hmm... I agree to iterate the nr_virtfn from total_VFs to 0, which keep the
original logic, before my patch.
> pci_iov_set_numvfs(dev, nr_virtfn);
>+ if (!iov->offset || (nr_virtfn > 1 && !iov->stride)) {
^^^
Should be this?
if (!iov->offset || (iov->total_VFs > 1 && !iov->stride))
>+ rc = -EIO;
>+ goto out;
>+ }
>+
> busnr = pci_iov_virtfn_bus(dev, nr_virtfn - 1);
>- if (busnr > max)
>- max = busnr;
>+ if (busnr > iov->max_VF_buses)
>+ iov->max_VF_buses = busnr;
> }
>
>- return max;
>+out:
>+ pci_iov_set_numvfs(dev, 0);
>+ return rc;
> }
>
> static struct pci_bus *virtfn_add_bus(struct pci_bus *bus, int busnr)
>@@ -384,7 +389,7 @@ 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;
>@@ -410,11 +415,6 @@ 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;
>
Original code will return when it found this condition, so that we don't need
to bother to do those initialization and then fall back.
So I suggest to keep it here.
> pci_read_config_word(dev, pos + PCI_SRIOV_TOTAL_VF, &total);
> if (!total)
>@@ -456,8 +456,6 @@ 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);
>@@ -474,10 +472,15 @@ found:
>
> dev->sriov = iov;
> dev->is_physfn = 1;
>- iov->max_VF_buses = virtfn_max_buses(dev);
>+ rc = compute_max_vf_buses(dev);
>+ if (rc)
>+ goto fail_max_buses;
>
> return 0;
>
>+fail_max_buses:
>+ dev->sriov = NULL;
The dev->sriov is allocated with kzalloc(), seems we forget to release it?
>+ dev->is_physfn = 0;
> failed:
> for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
> res = &dev->resource[i + PCI_IOV_R
--
Richard Yang
Help you, Help me
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