linux-kernel - [patch V3 24/35] PCI/MSI: Provide MSI_FLAG_MSIX

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Message-ID: <20211210221814.662401116@linutronix.de>
Date:   Fri, 10 Dec 2021 23:19:20 +0100 (CET)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Bjorn Helgaas <helgaas@...nel.org>, Marc Zygnier <maz@...nel.org>,
        Alex Williamson <alex.williamson@...hat.com>,
        Kevin Tian <kevin.tian@...el.com>,
        Jason Gunthorpe <jgg@...dia.com>,
        Megha Dey <megha.dey@...el.com>,
        Ashok Raj <ashok.raj@...el.com>, linux-pci@...r.kernel.org,
        Cedric Le Goater <clg@...d.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Juergen Gross <jgross@...e.com>,
        xen-devel@...ts.xenproject.org, Arnd Bergmann <arnd@...db.de>,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        linuxppc-dev@...ts.ozlabs.org, Stuart Yoder <stuyoder@...il.com>,
        Laurentiu Tudor <laurentiu.tudor@....com>,
        Nishanth Menon <nm@...com>, Tero Kristo <kristo@...nel.org>,
        Santosh Shilimkar <ssantosh@...nel.org>,
        linux-arm-kernel@...ts.infradead.org,
        Vinod Koul <vkoul@...nel.org>, dmaengine@...r.kernel.org,
        Mark Rutland <mark.rutland@....com>,
        Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Joerg Roedel <joro@...tes.org>,
        iommu@...ts.linux-foundation.org,
        Jassi Brar <jassisinghbrar@...il.com>,
        Peter Ujfalusi <peter.ujfalusi@...il.com>,
        Sinan Kaya <okaya@...nel.org>
Subject: [patch V3 24/35] PCI/MSI: Provide MSI_FLAG_MSIX_CONTIGUOUS

From: Thomas Gleixner <tglx@...utronix.de>

Provide a domain info flag which makes the core code check for a contiguous
MSI-X index on allocation. That's simpler than checking it at some other
domain callback in architecture code.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Reviewed-by: Jason Gunthorpe <jgg@...dia.com>
Acked-by: Bjorn Helgaas <bhelgaas@...gle.com>

---
 drivers/pci/msi/irqdomain.c |   16 ++++++++++++++--
 include/linux/msi.h         |    2 ++
 2 files changed, 16 insertions(+), 2 deletions(-)

--- a/drivers/pci/msi/irqdomain.c
+++ b/drivers/pci/msi/irqdomain.c
@@ -89,9 +89,21 @@ static int pci_msi_domain_check_cap(stru
 	if (pci_msi_desc_is_multi_msi(desc) &&
 	    !(info->flags & MSI_FLAG_MULTI_PCI_MSI))
 		return 1;
-	else if (desc->pci.msi_attrib.is_msix && !(info->flags & MSI_FLAG_PCI_MSIX))
-		return -ENOTSUPP;
 
+	if (desc->pci.msi_attrib.is_msix) {
+		if (!(info->flags & MSI_FLAG_PCI_MSIX))
+			return -ENOTSUPP;
+
+		if (info->flags & MSI_FLAG_MSIX_CONTIGUOUS) {
+			unsigned int idx = 0;
+
+			/* Check for gaps in the entry indices */
+			for_each_msi_entry(desc, dev) {
+				if (desc->msi_index != idx++)
+					return -ENOTSUPP;
+			}
+		}
+	}
 	return 0;
 }
 
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -361,6 +361,8 @@ enum {
 	MSI_FLAG_LEVEL_CAPABLE		= (1 << 6),
 	/* Populate sysfs on alloc() and destroy it on free() */
 	MSI_FLAG_DEV_SYSFS		= (1 << 7),
+	/* MSI-X entries must be contiguous */
+	MSI_FLAG_MSIX_CONTIGUOUS	= (1 << 8),
 };
 
 int msi_domain_set_affinity(struct irq_data *data, const struct cpumask *mask,