On 2021-01-25 14:39, Shameerali Kolothum Thodi wrote:
-----Original Message----- From: Marc Zyngier [mailto:maz@kernel.org] Sent: 23 January 2021 12:28 To: linux-kernel@vger.kernel.org Cc: Thomas Gleixner tglx@linutronix.de; Bjorn Helgaas bhelgaas@google.com; Shameerali Kolothum Thodi shameerali.kolothum.thodi@huawei.com; stable@vger.kernel.org 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@huawei.com Signed-off-by: Marc Zyngier maz@kernel.org Cc: stable@vger.kernel.org
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.
I'm not sure this matters either. We may have relied on these statements some 6/7 years ago, as the whole hierarchy stuff was brand new, but we now have a much better debug infrastructure thanks to Thomas. I'd be totally in favour of dropping it.
Thanks,
M.