Subject: [patch 36/39] PCI/MSI: Validate MSIX contiguous restriction early

From: Thomas Gleixner <[email-masked]>
Date: Fri, 11 Nov 2022 14:55:12 +0100 (CET)

With interrupt domains the sanity check for MSI-X vector validation can be
done _before_ any allocation happens. The sanity check only applies to the
allocation functions which have an 'entries' array argument. The entries
array is filled by the caller with the requested MSI-X indicies. Some drivers
have gaps in the index space which is not supported on all architectures.

The PCI/MSI irqdomain has a 'feature' bit to enforce this validation late
during the allocation phase.

Just do it right away before doing any other work along with the other
sanity checks on that array.

Signed-off-by: Thomas Gleixner <[email-masked]>
---
 drivers/pci/msi/msi.c |   11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

--- a/drivers/pci/msi/msi.c
+++ b/drivers/pci/msi/msi.c
@@ -725,13 +725,17 @@ static int msix_capability_init(struct p
 	return ret;
 }
 
-static bool pci_msix_validate_entries(struct msix_entry *entries, int nvec, int hwsize)
+static bool pci_msix_validate_entries(struct pci_dev *dev, struct msix_entry *entries,
+				      int nvec, int hwsize)
 {
+	bool nogap;
 	int i, j;
 
 	if (!entries)
 		return true;
 
+	nogap = pci_msi_domain_supports(dev, MSI_FLAG_MSIX_CONTIGUOUS, DENY_LEGACY);
+
 	for (i = 0; i < nvec; i++) {
 		/* Entry within hardware limit? */
 		if (entries[i].entry >= hwsize)
@@ -742,6 +746,9 @@ static bool pci_msix_validate_entries(st
 			if (entries[i].entry == entries[j].entry)
 				return false;
 		}
+		/* Check for unsupported gaps */
+		if (nogap && entries[i].entry != i)
+			return false;
 	}
 	return true;
 }
@@ -773,7 +780,7 @@ int __pci_enable_msix_range(struct pci_d
 	if (hwsize < 0)
 		return hwsize;
 
-	if (!pci_msix_validate_entries(entries, nvec, hwsize))
+	if (!pci_msix_validate_entries(dev, entries, nvec, hwsize))
 		return -EINVAL;
 
 	/* PCI_IRQ_VIRTUAL is a horrible hack! */