From: Leon Romanovsky <leon@kernel.org>
To: Alex Williamson <alex.williamson@redhat.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>,
Saeed Mahameed <saeedm@nvidia.com>,
Jason Gunthorpe <jgg@nvidia.com>,
Jakub Kicinski <kuba@kernel.org>,
linux-pci@vger.kernel.org, linux-rdma@vger.kernel.org,
netdev@vger.kernel.org, Don Dutile <ddutile@redhat.com>
Subject: Re: [PATCH mlx5-next v1 1/5] PCI: Add sysfs callback to allow MSI-X table size change of SR-IOV VFs
Date: Wed, 13 Jan 2021 21:49:18 +0200 [thread overview]
Message-ID: <20210113194918.GJ4678@unreal> (raw)
In-Reply-To: <20210113105052.43cf3c15@omen.home.shazbot.org>
On Wed, Jan 13, 2021 at 10:50:52AM -0700, Alex Williamson wrote:
> On Sun, 10 Jan 2021 17:07:23 +0200
> Leon Romanovsky <leon@kernel.org> wrote:
>
> > From: Leon Romanovsky <leonro@nvidia.com>
> >
> > Extend PCI sysfs interface with a new callback that allows configure
> > the number of MSI-X vectors for specific SR-IO VF. This is needed
> > to optimize the performance of newly bound devices by allocating
> > the number of vectors based on the administrator knowledge of targeted VM.
> >
> > This function is applicable for SR-IOV VF because such devices allocate
> > their MSI-X table before they will run on the VMs and HW can't guess the
> > right number of vectors, so the HW allocates them statically and equally.
> >
> > The newly added /sys/bus/pci/devices/.../vf_msix_vec file will be seen
> > for the VFs and it is writable as long as a driver is not bounded to the VF.
> >
> > The values accepted are:
> > * > 0 - this will be number reported by the VF's MSI-X capability
> > * < 0 - not valid
> > * = 0 - will reset to the device default value
> >
> > Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
> > ---
> > Documentation/ABI/testing/sysfs-bus-pci | 20 ++++++++
> > drivers/pci/iov.c | 62 +++++++++++++++++++++++++
> > drivers/pci/msi.c | 29 ++++++++++++
> > drivers/pci/pci-sysfs.c | 1 +
> > drivers/pci/pci.h | 2 +
> > include/linux/pci.h | 8 +++-
> > 6 files changed, 121 insertions(+), 1 deletion(-)
<...>
> > +/**
> > + * pci_set_msix_vec_count - change the reported number of MSI-X vectors
> > + * This function is applicable for SR-IOV VF because such devices allocate
> > + * their MSI-X table before they will run on the VMs and HW can't guess the
> > + * right number of vectors, so the HW allocates them statically and equally.
> > + * @dev: VF device that is going to be changed
> > + * @numb: amount of MSI-X vectors
> > + **/
> > +int pci_set_msix_vec_count(struct pci_dev *dev, int numb)
> > +{
> > + struct pci_dev *pdev = pci_physfn(dev);
> > +
> > + if (!dev->msix_cap || !pdev->msix_cap)
> > + return -EINVAL;
> > +
> > + if (dev->driver || !pdev->driver ||
> > + !pdev->driver->sriov_set_msix_vec_count)
> > + return -EOPNOTSUPP;
>
>
> This seems racy, don't we need to hold device_lock on both the VF and
> PF to avoid driver {un}binding races? Does that happen implicitly
> somewhere? Thanks,
Yes, you are right absolutely, pdev and dev are not protected here.
Thanks
next prev parent reply other threads:[~2021-01-13 19:50 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-10 15:07 [PATCH mlx5-next v1 0/5] Dynamically assign MSI-X vectors count Leon Romanovsky
2021-01-10 15:07 ` [PATCH mlx5-next v1 1/5] PCI: Add sysfs callback to allow MSI-X table size change of SR-IOV VFs Leon Romanovsky
2021-01-11 19:30 ` Alexander Duyck
2021-01-12 3:25 ` Don Dutile
2021-01-12 6:15 ` Leon Romanovsky
2021-01-12 6:39 ` Leon Romanovsky
2021-01-12 21:59 ` Alexander Duyck
2021-01-13 6:09 ` Leon Romanovsky
2021-01-13 20:00 ` Alexander Duyck
2021-01-14 7:16 ` Leon Romanovsky
2021-01-14 16:51 ` Alexander Duyck
2021-01-14 17:12 ` Leon Romanovsky
2021-01-13 17:50 ` Alex Williamson
2021-01-13 19:49 ` Leon Romanovsky [this message]
2021-01-10 15:07 ` [PATCH mlx5-next v1 2/5] PCI: Add SR-IOV sysfs entry to read number of MSI-X vectors Leon Romanovsky
2021-01-11 19:30 ` Alexander Duyck
2021-01-12 6:56 ` Leon Romanovsky
2021-01-12 21:34 ` Alexander Duyck
2021-01-13 6:19 ` Leon Romanovsky
2021-01-13 22:44 ` Alexander Duyck
2021-01-14 6:50 ` Leon Romanovsky
2021-01-14 16:40 ` Alexander Duyck
2021-01-14 16:48 ` Jason Gunthorpe
2021-01-14 17:55 ` Alexander Duyck
2021-01-14 18:29 ` Jason Gunthorpe
2021-01-14 19:24 ` Alexander Duyck
2021-01-14 19:56 ` Leon Romanovsky
2021-01-14 20:08 ` Jason Gunthorpe
2021-01-14 21:43 ` Alexander Duyck
2021-01-14 23:28 ` Alex Williamson
2021-01-15 1:56 ` Alexander Duyck
2021-01-15 14:06 ` Jason Gunthorpe
2021-01-15 15:53 ` Leon Romanovsky
2021-01-16 1:48 ` Alexander Duyck
2021-01-16 8:20 ` Leon Romanovsky
2021-01-18 3:16 ` Alexander Duyck
2021-01-18 7:20 ` Leon Romanovsky
2021-01-18 13:28 ` Leon Romanovsky
2021-01-18 18:21 ` Alexander Duyck
2021-01-19 5:43 ` Leon Romanovsky
2021-01-16 4:32 ` Alexander Duyck
2021-01-18 15:47 ` Jason Gunthorpe
2021-01-15 13:51 ` Jason Gunthorpe
2021-01-14 17:26 ` Leon Romanovsky
2021-01-18 17:03 ` Greg KH
2021-01-19 5:38 ` Leon Romanovsky
2021-01-10 15:07 ` [PATCH mlx5-next v1 3/5] net/mlx5: Add dynamic MSI-X capabilities bits Leon Romanovsky
2021-01-10 15:07 ` [PATCH mlx5-next v1 4/5] net/mlx5: Dynamically assign MSI-X vectors count Leon Romanovsky
2021-01-10 15:07 ` [PATCH mlx5-next v1 5/5] net/mlx5: Allow to the users to configure number of MSI-X vectors Leon Romanovsky
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