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Date:   Mon, 05 Dec 2022 18:25:12 -0000
From:   "tip-bot2 for Thomas Gleixner" <tip-bot2@linutronix.de>
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Subject: [tip: irq/core] genirq/msi: Provide MSI_FLAG_MSIX_ALLOC_DYN
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Jason Gunthorpe <jgg@nvidia.com>,
        Kevin Tian <kevin.tian@intel.com>,
        Marc Zyngier <maz@kernel.org>, x86@kernel.org,
        linux-kernel@vger.kernel.org
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The following commit has been merged into the irq/core branch of tip:

Commit-ID:     656013915af76b199827f26e18776d897d2b7e7e
Gitweb:        https://git.kernel.org/tip/656013915af76b199827f26e18776d897d2b7e7e
Author:        Thomas Gleixner <tglx@linutronix.de>
AuthorDate:    Fri, 25 Nov 2022 00:26:20 +01:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Mon, 05 Dec 2022 19:21:03 +01:00

genirq/msi: Provide MSI_FLAG_MSIX_ALLOC_DYN

Provide a new MSI feature flag in preparation for dynamic MSIX allocation
after the initial MSI-X enable has been done.

This needs to be an explicit MSI interrupt domain feature because quite
some implementations (both interrupt domains and legacy allocation mode)
have clear expectations that the allocation code is only invoked when MSI-X
is about to be enabled. They either talk to hypervisors or do some other
work and are not prepared to be invoked on an already MSI-X enabled device.

This is also explicit MSI-X only because rewriting the size of the MSI
entries is only possible when disabling MSI which in turn might cause lost
interrupts on the device.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221124232326.558843119@linutronix.de

---
 include/linux/msi.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/linux/msi.h b/include/linux/msi.h
index 00c5019..3cb1586 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -557,7 +557,8 @@ enum {
 	MSI_FLAG_LEVEL_CAPABLE		= (1 << 18),
 	/* MSI-X entries must be contiguous */
 	MSI_FLAG_MSIX_CONTIGUOUS	= (1 << 19),
-
+	/* PCI/MSI-X vectors can be dynamically allocated/freed post MSI-X enable */
+	MSI_FLAG_PCI_MSIX_ALLOC_DYN	= (1 << 20),
 };
 
 /**