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SubjectRe: [PATCH AUTOSEL 5.16 36/52] PCI/MSI: Decouple MSI[-X] disable from pcim_release()
On Mon, Jan 17, 2022 at 11:58:37AM -0500, Sasha Levin wrote:
> From: Thomas Gleixner <tglx@linutronix.de>
>
> [ Upstream commit 3f35d2cf9fbc656db82579d849cc69c373b1ad0d ]
>
> The MSI core will introduce runtime allocation of MSI related data. This
> data will be devres managed and has to be set up before enabling
> PCI/MSI[-X]. This would introduce an ordering issue vs. pcim_release().
>
> The setup order is:
>
> pcim_enable_device()
> devres_alloc(pcim_release...);
> ...
> pci_irq_alloc()
> msi_setup_device_data()
> devres_alloc(msi_device_data_release, ...)
>
> and once the device is released these release functions are invoked in the
> opposite order:
>
> msi_device_data_release()
> ...
> pcim_release()
> pci_disable_msi[x]()
>
> which is obviously wrong, because pci_disable_msi[x]() requires the MSI
> data to be available to tear down the MSI[-X] interrupts.
>
> Remove the MSI[-X] teardown from pcim_release() and add an explicit action
> to be installed on the attempt of enabling PCI/MSI[-X].
>
> This allows the MSI core data allocation to be ordered correctly in a
> subsequent step.
>
> Reported-by: Nishanth Menon <nm@ti.com>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Tested-by: Michael Kelley <mikelley@microsoft.com>
> Tested-by: Nishanth Menon <nm@ti.com>
> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Link: https://lore.kernel.org/r/87tuf9rdoj.ffs@tglx
> Signed-off-by: Sasha Levin <sashal@kernel.org>
> ---
> drivers/pci/msi.c | 33 +++++++++++++++++++++++++++++++++
> drivers/pci/pci.c | 5 -----
> include/linux/pci.h | 3 ++-
> 3 files changed, 35 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
> index d84cf30bb2790..1093f099846eb 100644
> --- a/drivers/pci/msi.c
> +++ b/drivers/pci/msi.c
> @@ -461,6 +461,31 @@ void pci_restore_msi_state(struct pci_dev *dev)
> }
> EXPORT_SYMBOL_GPL(pci_restore_msi_state);
>
> +static void pcim_msi_release(void *pcidev)
> +{
> + struct pci_dev *dev = pcidev;
> +
> + dev->is_msi_managed = false;
> + pci_free_irq_vectors(dev);
> +}
> +
> +/*
> + * Needs to be separate from pcim_release to prevent an ordering problem
> + * vs. msi_device_data_release() in the MSI core code.
> + */
> +static int pcim_setup_msi_release(struct pci_dev *dev)
> +{
> + int ret;
> +
> + if (!pci_is_managed(dev) || dev->is_msi_managed)
> + return 0;
> +
> + ret = devm_add_action(&dev->dev, pcim_msi_release, dev);
> + if (!ret)
> + dev->is_msi_managed = true;
> + return ret;
> +}
> +
> static struct msi_desc *
> msi_setup_entry(struct pci_dev *dev, int nvec, struct irq_affinity *affd)
> {
> @@ -1029,6 +1054,10 @@ static int __pci_enable_msi_range(struct pci_dev *dev, int minvec, int maxvec,
> if (nvec > maxvec)
> nvec = maxvec;
>
> + rc = pcim_setup_msi_release(dev);
> + if (rc)
> + return rc;
> +
> for (;;) {
> if (affd) {
> nvec = irq_calc_affinity_vectors(minvec, nvec, affd);
> @@ -1072,6 +1101,10 @@ static int __pci_enable_msix_range(struct pci_dev *dev,
> if (WARN_ON_ONCE(dev->msix_enabled))
> return -EINVAL;
>
> + rc = pcim_setup_msi_release(dev);
> + if (rc)
> + return rc;
> +
> for (;;) {
> if (affd) {
> nvec = irq_calc_affinity_vectors(minvec, nvec, affd);
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 3d2fb394986a4..f3f606c232a8a 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -2024,11 +2024,6 @@ static void pcim_release(struct device *gendev, void *res)
> struct pci_devres *this = res;
> int i;
>
> - if (dev->msi_enabled)
> - pci_disable_msi(dev);
> - if (dev->msix_enabled)
> - pci_disable_msix(dev);
> -
> for (i = 0; i < DEVICE_COUNT_RESOURCE; i++)
> if (this->region_mask & (1 << i))
> pci_release_region(dev, i);
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 18a75c8e615cd..e26000404e3c3 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -425,7 +425,8 @@ struct pci_dev {
> unsigned int ats_enabled:1; /* Address Translation Svc */
> unsigned int pasid_enabled:1; /* Process Address Space ID */
> unsigned int pri_enabled:1; /* Page Request Interface */
> - unsigned int is_managed:1;
> + unsigned int is_managed:1; /* Managed via devres */
> + unsigned int is_msi_managed:1; /* MSI release via devres installed */
> unsigned int needs_freset:1; /* Requires fundamental reset */
> unsigned int state_saved:1;
> unsigned int is_physfn:1;
> --
> 2.34.1
>

I do not think this is needed for the stable trees, as it only showed up
in the MSI rework that Thomas added for 5.17-rc1. So please drop this
from all of the AUTOSEL kernels.

thanks,

greg k-h

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