lkml.org 
[lkml]   [2023]   [Oct]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH net] net/mlx5: fix calling mlx5_cmd_init() before DMA mask is set
    On 29 Sep 13:31, Leon Romanovsky wrote:
    >On Fri, Sep 29, 2023 at 11:40:49AM +0200, Niklas Schnelle wrote:
    >> On Thu, 2023-09-28 at 20:59 +0300, Leon Romanovsky wrote:
    >> > On Thu, Sep 28, 2023 at 03:55:47PM +0200, Niklas Schnelle wrote:
    >> > > Since commit 06cd555f73ca ("net/mlx5: split mlx5_cmd_init() to probe and
    >> > > reload routines") mlx5_cmd_init() is called in mlx5_mdev_init() which is
    >> > > called in probe_one() before mlx5_pci_init(). This is a problem because
    >> > > mlx5_pci_init() is where the DMA and coherent mask is set but
    >> > > mlx5_cmd_init() already does a dma_alloc_coherent(). Thus a DMA
    >> > > allocation is done during probe before the correct mask is set. This
    >> > > causes probe to fail initialization of the cmdif SW structs on s390x
    >> > > after that is converted to the common dma-iommu code. This is because on
    >> > > s390x DMA addresses below 4 GiB are reserved on current machines and
    >> > > unlike the old s390x specific DMA API implementation common code
    >> > > enforces DMA masks. Fix this by switching the order of the
    >> > > mlx5_mdev_init() and mlx5_pci_init() in probe_one().
    >> > >
    >> > > Link: https://lore.kernel.org/linux-iommu/cfc9e9128ed5571d2e36421e347301057662a09e.camel@linux.ibm.com/
    >> > > Fixes: 06cd555f73ca ("net/mlx5: split mlx5_cmd_init() to probe and reload routines")
    >> > > Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
    >> > > ---
    >> > > Note: I ran into this while testing the linked series for converting
    >> > > s390x to use dma-iommu. The existing s390x specific DMA API
    >> > > implementation doesn't respect DMA masks and is thus not affected
    >> > > despite of course also only supporting DMA addresses above 4 GiB.
    >> > > That said ConnectX VFs are the primary users of native PCI on s390x and
    >> > > we'd really like to get the DMA API conversion into v6.7 so this has
    >> > > high priority for us.
    >> > > ---
    >> > > drivers/net/ethernet/mellanox/mlx5/core/main.c | 12 ++++++------
    >> > > 1 file changed, 6 insertions(+), 6 deletions(-)
    >> > >
    >> > > diff --git a/drivers/net/ethernet/mellanox/mlx5/core/main.c b/drivers/net/ethernet/mellanox/mlx5/core/main.c
    >> > > index 15561965d2af..06744dedd928 100644
    >> > > --- a/drivers/net/ethernet/mellanox/mlx5/core/main.c
    >> > > +++ b/drivers/net/ethernet/mellanox/mlx5/core/main.c
    >> > > @@ -1908,10 +1908,6 @@ static int probe_one(struct pci_dev *pdev, const struct pci_device_id *id)
    >> > > goto adev_init_err;
    >> > > }
    >> > >
    >> > > - err = mlx5_mdev_init(dev, prof_sel);
    >> > > - if (err)
    >> > > - goto mdev_init_err;
    >> > > -
    >> > > err = mlx5_pci_init(dev, pdev, id);
    >> > > if (err) {
    >> > > mlx5_core_err(dev, "mlx5_pci_init failed with error code %d\n",
    >> > > @@ -1919,6 +1915,10 @@ static int probe_one(struct pci_dev *pdev, const struct pci_device_id *id)
    >> > > goto pci_init_err;
    >> > > }
    >> > >
    >> > > + err = mlx5_mdev_init(dev, prof_sel);
    >> > > + if (err)
    >> > > + goto mdev_init_err;
    >> > > +
    >> >
    >> > I had something different in mind as I'm worry that call to pci_enable_device()
    >> > in mlx5_pci_init() before we finished FW command interface initialization is a bit
    >> > premature.
    >> >
    >> > What about the following patch?
    >> >
    >> > diff --git a/drivers/net/ethernet/mellanox/mlx5/core/main.c b/drivers/net/ethernet/mellanox/mlx5/core/main.c
    >> > index 15561965d2af..31f1d701116a 100644
    >> > --- a/drivers/net/ethernet/mellanox/mlx5/core/main.c
    >> > +++ b/drivers/net/ethernet/mellanox/mlx5/core/main.c
    >> > @@ -905,12 +905,6 @@ static int mlx5_pci_init(struct mlx5_core_dev *dev, struct pci_dev *pdev,
    >> >
    >> > pci_set_master(pdev);
    >> >
    >> > - err = set_dma_caps(pdev);
    >> > - if (err) {
    >> > - mlx5_core_err(dev, "Failed setting DMA capabilities mask, aborting\n");
    >> > - goto err_clr_master;
    >> > - }
    >> > -
    >> > if (pci_enable_atomic_ops_to_root(pdev, PCI_EXP_DEVCAP2_ATOMIC_COMP32) &&
    >> > pci_enable_atomic_ops_to_root(pdev, PCI_EXP_DEVCAP2_ATOMIC_COMP64) &&
    >> > pci_enable_atomic_ops_to_root(pdev, PCI_EXP_DEVCAP2_ATOMIC_COMP128))
    >> > @@ -1908,9 +1902,15 @@ static int probe_one(struct pci_dev *pdev, const struct pci_device_id *id)
    >> > goto adev_init_err;
    >> > }
    >> >
    >> > + err = set_dma_caps(pdev);
    >> > + if (err) {
    >> > + mlx5_core_err(dev, "Failed setting DMA capabilities mask, aborting\n");
    >> > + goto dma_cap_err;
    >> > + }
    >> > +
    >> > err = mlx5_mdev_init(dev, prof_sel);
    >> > if (err)
    >> > - goto mdev_init_err;
    >> > + goto dma_cap_err;
    >> >
    >> > err = mlx5_pci_init(dev, pdev, id);
    >> > if (err) {
    >> > @@ -1942,7 +1942,7 @@ static int probe_one(struct pci_dev *pdev, const struct pci_device_id *id)
    >> > mlx5_pci_close(dev);
    >> > pci_init_err:
    >> > mlx5_mdev_uninit(dev);
    >> > -mdev_init_err:
    >> > +dma_cap_err:
    >> > mlx5_adev_idx_free(dev->priv.adev_idx);
    >> > adev_init_err:
    >> > mlx5_devlink_free(devlink);
    >> >
    >> > Thanks
    >>
    >> The above works too. Maybe for consistency within probe_one() it would
    >> then make sense to also rename set_dma_caps() to mlx5_dma_init()?
    >
    >Sounds great, thanks
    >
    >BTW, I was informed offlist that Saeed also has fix to this issue,
    >but I don't know if he wants to progress with that fix as it has wrong
    >RCA in commit message and as an outcome of that much complex solution,
    >which is not necessary.
    >
    >So I would be happy to see your patch with mlx5_dma_init().
    >
    >Thanks
    >

    Actually I prefer the internal patch, it moves the dma parts out of
    mlx5_cmd_init() into mlx5_cmd_enable() which happens after dma caps are
    set. since it is using the current mlx5 function structure and breakdown,
    I prefer it over adding new function to the driver.

    I will share the patch, I will let Niklas test it and approve it before
    submission.

    Thanks,
    Saeed.

    >

    \
     
     \ /
      Last update: 2023-10-11 20:45    [W:5.568 / U:0.008 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site