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authorMarc Zyngier <marc.zyngier@arm.com>2016-07-13 17:18:33 +0100
committerThomas Gleixner <tglx@linutronix.de>2016-08-09 09:19:32 +0200
commitf3b0946d629c8bfbd3e5f038e30cb9c711a35f10 (patch)
treedb1a60c625dab7f046cef8f4975f5fbed151a3dc /kernel/irq
parent81abf2525827b29839a78fd55ab0699f033c41a5 (diff)
genirq/msi: Make sure PCI MSIs are activated early
Bharat Kumar Gogada reported issues with the generic MSI code, where the end-point ended up with garbage in its MSI configuration (both for the vector and the message). It turns out that the two MSI paths in the kernel are doing slightly different things: generic MSI: disable MSI -> allocate MSI -> enable MSI -> setup EP PCI MSI: disable MSI -> allocate MSI -> setup EP -> enable MSI And it turns out that end-points are allowed to latch the content of the MSI configuration registers as soon as MSIs are enabled. In Bharat's case, the end-point ends up using whatever was there already, which is not what you want. In order to make things converge, we introduce a new MSI domain flag (MSI_FLAG_ACTIVATE_EARLY) that is unconditionally set for PCI/MSI. When set, this flag forces the programming of the end-point as soon as the MSIs are allocated. A consequence of this is that we have an extra activate in irq_startup, but that should be without much consequence. tglx: - Several people reported a VMWare regression with PCI/MSI-X passthrough. It turns out that the patch also cures that issue. - We need to have a look at the MSI disable interrupt path, where we write the msg to all zeros without disabling MSI in the PCI device. Is that correct? Fixes: 52f518a3a7c2 "x86/MSI: Use hierarchical irqdomains to manage MSI interrupts" Reported-and-tested-by: Bharat Kumar Gogada <bharat.kumar.gogada@xilinx.com> Reported-and-tested-by: Foster Snowhill <forst@forstwoof.ru> Reported-by: Matthias Prager <linux@matthiasprager.de> Reported-by: Jason Taylor <jason.taylor@simplivity.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Acked-by: Bjorn Helgaas <bhelgaas@google.com> Cc: linux-pci@vger.kernel.org Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/1468426713-31431-1-git-send-email-marc.zyngier@arm.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel/irq')
-rw-r--r--kernel/irq/msi.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/kernel/irq/msi.c b/kernel/irq/msi.c
index 54999350162c..19e9dfbe97fa 100644
--- a/kernel/irq/msi.c
+++ b/kernel/irq/msi.c
@@ -359,6 +359,17 @@ int msi_domain_alloc_irqs(struct irq_domain *domain, struct device *dev,
else
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) {
+ struct irq_data *irq_data;
+
+ irq_data = irq_domain_get_irq_data(domain, desc->irq);
+ irq_domain_activate_irq(irq_data);
+ }
}
return 0;