-----Original Message-----
From: Marc Zyngier [mailto:[email protected]]
Sent: 23 January 2021 12:28
To: [email protected]
Cc: Thomas Gleixner <[email protected]>; Bjorn Helgaas
<[email protected]>; Shameerali Kolothum Thodi
<[email protected]>; [email protected]
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 <[email protected]>
Signed-off-by: Marc Zyngier <[email protected]>
Cc: [email protected]
---
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;
