On 12/1/20 8:39 AM, Alexey Kardashevskiy wrote:
> From: Oliver O'Halloran <ooh...@gmail.com>
>
> When a passthrough IO adapter is removed from a pseries machine using hash
> MMU and the XIVE interrupt mode, the POWER hypervisor expects the guest OS
> to clear all page table entries related to the adapter. If some are still
> present, the RTAS call which isolates the PCI slot returns error 9001
> "valid outstanding translations" and the removal of the IO adapter fails.
> This is because when the PHBs are scanned, Linux maps automatically the
> INTx interrupts in the Linux interrupt number space but these are never
> removed.
>
> This problem can be fixed by adding the corresponding unmap operation when
> the device is removed. There's no pcibios_* hook for the remove case, but
> the same effect can be achieved using a bus notifier.
>
> Because INTx are shared among PHBs (and potentially across the system),
> this adds tracking of virq to unmap them only when the last user is gone.
>
> Signed-off-by: Oliver O'Halloran <ooh...@gmail.com>
> [aik: added refcounter]
> Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru>
Looks good to me and the system survives all the PCI hotplug tests I used
to do on my first attempts to fix this issue.
One comment below,
> ---
>
>
> Doing this in the generic irq code is just too much for my small brain :-/
may be more cleanups are required in the PCI/MSI/IRQ PPC layers before
considering your first approach. You think too much in advance !
>
> ---
> arch/powerpc/kernel/pci-common.c | 71 ++++++++++++++++++++++++++++++++
> 1 file changed, 71 insertions(+)
>
> diff --git a/arch/powerpc/kernel/pci-common.c
> b/arch/powerpc/kernel/pci-common.c
> index be108616a721..0acf17f17253 100644
> --- a/arch/powerpc/kernel/pci-common.c
> +++ b/arch/powerpc/kernel/pci-common.c
> @@ -353,6 +353,55 @@ struct pci_controller
> *pci_find_controller_for_domain(int domain_nr)
> return NULL;
> }
>
> +struct pci_intx_virq {
> + int virq;
> + struct kref kref;
> + struct list_head list_node;
> +};
> +
> +static LIST_HEAD(intx_list);
> +static DEFINE_MUTEX(intx_mutex);
> +
> +static void ppc_pci_intx_release(struct kref *kref)
> +{
> + struct pci_intx_virq *vi = container_of(kref, struct pci_intx_virq,
> kref);
> +
> + list_del(&vi->list_node);
> + irq_dispose_mapping(vi->virq);
> + kfree(vi);
> +}
> +
> +static int ppc_pci_unmap_irq_line(struct notifier_block *nb,
> + unsigned long action, void *data)
> +{
> + struct pci_dev *pdev = to_pci_dev(data);
> +
> + if (action == BUS_NOTIFY_DEL_DEVICE) {
> + struct pci_intx_virq *vi;
> +
> + mutex_lock(&intx_mutex);
> + list_for_each_entry(vi, &intx_list, list_node) {
> + if (vi->virq == pdev->irq) {
> + kref_put(&vi->kref, ppc_pci_intx_release);
> + break;
> + }
> + }
> + mutex_unlock(&intx_mutex);
> + }
> +
> + return NOTIFY_DONE;
> +}
> +
> +static struct notifier_block ppc_pci_unmap_irq_notifier = {
> + .notifier_call = ppc_pci_unmap_irq_line,
> +};
> +
> +static int ppc_pci_register_irq_notifier(void)
> +{
> + return bus_register_notifier(&pci_bus_type,
> &ppc_pci_unmap_irq_notifier);
> +}
> +arch_initcall(ppc_pci_register_irq_notifier);
> +
> /*
> * Reads the interrupt pin to determine if interrupt is use by card.
> * If the interrupt is used, then gets the interrupt line from the
> @@ -361,6 +410,12 @@ struct pci_controller
> *pci_find_controller_for_domain(int domain_nr)
> static int pci_read_irq_line(struct pci_dev *pci_dev)
> {
> int virq;
> + struct pci_intx_virq *vi, *vitmp;
> +
> + /* Preallocate vi as rewind is complex if this fails after mapping */
AFAICT, we only need to call irq_dispose_mapping() if allocation fails.
If so, it would be simpler to isolate the code in a pci_intx_register(virq)
helper and call it from pci_read_irq_line().
> + vi = kzalloc(sizeof(struct pci_intx_virq), GFP_KERNEL);
> + if (!vi)
> + return -1;
>
> pr_debug("PCI: Try to map irq for %s...\n", pci_name(pci_dev));
>
> @@ -401,6 +456,22 @@ static int pci_read_irq_line(struct pci_dev *pci_dev)
>
> pci_dev->irq = virq;
>
> + mutex_lock(&intx_mutex);
> + list_for_each_entry(vitmp, &intx_list, list_node) {
> + if (vitmp->virq == virq) {
> + kref_get(&vitmp->kref);
> + kfree(vi);
> + vi = NULL;
> + break;
> + }
> + }
> + if (vi) {
> + vi->virq = virq;
> + kref_init(&vi->kref);
> + list_add_tail(&vi->list_node, &intx_list);
> + }
> + mutex_unlock(&intx_mutex);
> +
> return 0;
> }
>
>
