Hi Ben,
On Fri, Sep 11, 2015 at 04:55:00PM -0500, Ben Shelton wrote:
> For some SR-IOV devices, the number of available virtual functions
> increases after enabling ARI. Currently, SRIOV_NUM_VF is read and saved
> off before the ARI control bit is enabled. This causes an issue when VFs
> are enabled.
>
> At device init, SRIOV_INITIAL_VF and SRIOV_NUM_VF are specified to contain
> the number of available VFs for the device. sriov_enable() does a sanity
> check that PCI_SRIOV_INITIAL_VF is not greater than iov->total_VFs, the
> saved-off value of SRIOV_NUM_VF. Since the value of both SRIOV_INITIAL_VF
> and SRIOV_NUM_VF has increased after enabling the ARI bit, the check fails,
> and the VFs cannot be enabled.
>
> To fix the issue, after ARI is enabled for a device, reread SRIOV_NUM_VF.
>
> Signed-off-by: Ben Shelton <benjamin.h.shelton@xxxxxxxxx>
> ---
> drivers/pci/iov.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
> index ee0ebff..88b1959 100644
> --- a/drivers/pci/iov.c
> +++ b/drivers/pci/iov.c
> @@ -388,6 +388,7 @@ static int sriov_init(struct pci_dev *dev, int pos)
> struct pci_sriov *iov;
> struct resource *res;
> struct pci_dev *pdev;
> + bool total_needs_reread = false;
>
> if (pci_pcie_type(dev) != PCI_EXP_TYPE_RC_END &&
> pci_pcie_type(dev) != PCI_EXP_TYPE_ENDPOINT)
> @@ -409,12 +410,18 @@ static int sriov_init(struct pci_dev *dev, int pos)
> goto found;
>
> pdev = NULL;
> - if (pci_ari_enabled(dev->bus))
> + if (pci_ari_enabled(dev->bus)) {
> ctrl |= PCI_SRIOV_CTRL_ARI;
> + total_needs_reread = true;
> + }
>
> found:
> pci_write_config_word(dev, pos + PCI_SRIOV_CTRL, ctrl);
> pci_write_config_word(dev, pos + PCI_SRIOV_NUM_VF, 0);
> +
> + if (total_needs_reread)
> + pci_read_config_word(dev, pos + PCI_SRIOV_TOTAL_VF, &total);
Can we just *move* the PCI_SRIOV_TOTAL_VF read from its original
location and do it unconditionally here? I don't think we use "total"
for anything in the interim, and it'd be nice if we could do this
without the "total_needs_reread" flag.
> 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))
> --
> 1.9.5
>
> --
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