> -----Original Message----- > From: Marc Zyngier [mailto:maz@xxxxxxxxxx] > Sent: 23 January 2021 12:28 > To: linux-kernel@xxxxxxxxxxxxxxx > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>; Bjorn Helgaas > <bhelgaas@xxxxxxxxxx>; Shameerali Kolothum Thodi > <shameerali.kolothum.thodi@xxxxxxxxxx>; stable@xxxxxxxxxxxxxxx > Subject: [PATCH] genirq/msi: Activate Multi-MSI early when > MSI_FLAG_ACTIVATE_EARLY is set > > When MSI_FLAG_ACTIVATE_EARLY is set (which is the case for PCI), > we perform the activation of the interrupt (which in the case of > PCI results in the endpoint being programmed) as soon as the > interrupt is allocated. > > But it appears that this is only done for the first vector, > introducing an inconsistent behaviour for PCI Multi-MSI. > > Fix it by iterating over the number of vectors allocated to > each MSI descriptor. This is easily achieved by introducing > a new "for_each_msi_vector" iterator, together with a tiny > bit of refactoring. > > Fixes: f3b0946d629c ("genirq/msi: Make sure PCI MSIs are activated early") > Reported-by: Shameer Kolothum <shameerali.kolothum.thodi@xxxxxxxxxx> > Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx> > Cc: stable@xxxxxxxxxxxxxxx > --- > include/linux/msi.h | 6 ++++++ > kernel/irq/msi.c | 44 ++++++++++++++++++++------------------------ > 2 files changed, 26 insertions(+), 24 deletions(-) > > diff --git a/include/linux/msi.h b/include/linux/msi.h > index 360a0a7e7341..aef35fd1cf11 100644 > --- a/include/linux/msi.h > +++ b/include/linux/msi.h > @@ -178,6 +178,12 @@ struct msi_desc { > list_for_each_entry((desc), dev_to_msi_list((dev)), list) > #define for_each_msi_entry_safe(desc, tmp, dev) \ > list_for_each_entry_safe((desc), (tmp), dev_to_msi_list((dev)), list) > +#define for_each_msi_vector(desc, __irq, dev) \ > + for_each_msi_entry((desc), (dev)) \ > + if ((desc)->irq) \ > + for (__irq = (desc)->irq; \ > + __irq < ((desc)->irq + (desc)->nvec_used); \ > + __irq++) > > #ifdef CONFIG_IRQ_MSI_IOMMU > static inline const void *msi_desc_get_iommu_cookie(struct msi_desc *desc) > diff --git a/kernel/irq/msi.c b/kernel/irq/msi.c > index 2c0c4d6d0f83..d924676c8781 100644 > --- a/kernel/irq/msi.c > +++ b/kernel/irq/msi.c > @@ -436,22 +436,22 @@ int __msi_domain_alloc_irqs(struct irq_domain > *domain, struct device *dev, > > can_reserve = msi_check_reservation_mode(domain, info, dev); > > - for_each_msi_entry(desc, dev) { > - virq = desc->irq; > - if (desc->nvec_used == 1) > - dev_dbg(dev, "irq %d for MSI\n", virq); > - else > + /* > + * This flag is set by the PCI layer as we need to activate > + * the MSI entries before the PCI layer enables MSI in the > + * card. Otherwise the card latches a random msi message. > + */ > + if (!(info->flags & MSI_FLAG_ACTIVATE_EARLY)) > + goto skip_activate; This will change the dbg print behavior. From the commit f3b0946d629c, it looks like the below dev_dbg() code was there for !MSI_FLAG_ACTIVATE_EARLY case as well. Not sure how much this matters though. Thanks, Shameer > + > + for_each_msi_vector(desc, i, dev) { > + if (desc->irq == i) { > + virq = desc->irq; > dev_dbg(dev, "irq [%d-%d] for MSI\n", > virq, virq + desc->nvec_used - 1); > - /* > - * This flag is set by the PCI layer as we need to activate > - * the MSI entries before the PCI layer enables MSI in the > - * card. Otherwise the card latches a random msi message. > - */ > - if (!(info->flags & MSI_FLAG_ACTIVATE_EARLY)) > - continue; > + } > > - irq_data = irq_domain_get_irq_data(domain, desc->irq); > + irq_data = irq_domain_get_irq_data(domain, i); > if (!can_reserve) { > irqd_clr_can_reserve(irq_data); > if (domain->flags & IRQ_DOMAIN_MSI_NOMASK_QUIRK) > @@ -462,28 +462,24 @@ int __msi_domain_alloc_irqs(struct irq_domain > *domain, struct device *dev, > goto cleanup; > } > > +skip_activate: > /* > * If these interrupts use reservation mode, clear the activated bit > * so request_irq() will assign the final vector. > */ > if (can_reserve) { > - for_each_msi_entry(desc, dev) { > - irq_data = irq_domain_get_irq_data(domain, desc->irq); > + for_each_msi_vector(desc, i, dev) { > + irq_data = irq_domain_get_irq_data(domain, i); > irqd_clr_activated(irq_data); > } > } > return 0; > > cleanup: > - for_each_msi_entry(desc, dev) { > - struct irq_data *irqd; > - > - if (desc->irq == virq) > - break; > - > - irqd = irq_domain_get_irq_data(domain, desc->irq); > - if (irqd_is_activated(irqd)) > - irq_domain_deactivate_irq(irqd); > + for_each_msi_vector(desc, i, dev) { > + irq_data = irq_domain_get_irq_data(domain, i); > + if (irqd_is_activated(irq_data)) > + irq_domain_deactivate_irq(irq_data); > } > msi_domain_free_irqs(domain, dev); > return ret; > -- > 2.29.2
