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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 /include
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 'include')
-rw-r--r--include/linux/msi.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/msi.h b/include/linux/msi.h
index 4f0bfe5912b2..e8c81fbd5f9c 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -270,6 +270,8 @@ enum {
MSI_FLAG_MULTI_PCI_MSI = (1 << 2),
/* Support PCI MSIX interrupts */
MSI_FLAG_PCI_MSIX = (1 << 3),
+ /* Needs early activate, required for PCI */
+ MSI_FLAG_ACTIVATE_EARLY = (1 << 4),
};
int msi_domain_set_affinity(struct irq_data *data, const struct cpumask *mask,