From: AMEET M. PARANJAPE <aparanja@redhat.com>
Date: Tue, 31 Mar 2009 11:05:36 -0400
Subject: [ppc] reject discontiguous MSI-X requests
Message-id: 20090331150323.14954.43782.sendpatchset@squad5-lp1.lab.bos.redhat.com
O-Subject: [PATCH RHEL5.4 BZ492580 8/8]
Bugzilla: 492580
RH-Acked-by: David Howells <dhowells@redhat.com>

RHBZ#:
======
https://bugzilla.redhat.com/show_bug.cgi?id=492580

Description:
===========
There's no way for us to express to firmware that we want a
discontiguous, or non-zero based, range of MSI-X entries. So we
must reject such requests.

RHEL Version Found:
================
RHEL 5.3

kABI Status:
============
No symbols were harmed.

Brew:
=====
Built on all platforms.
http://brewweb.devel.redhat.com/brew/taskinfo?taskID=1744271

Upstream Status:
================
http://git.kernel.org/?p=linux/kernel/git/benh/powerpc.git;a=commit;h=94afa5a5f54235c4612198768b6a2fa2e2366f44

Test Status:
============
There is a testcase provided in the Bugzilla.  A 'cat /proc/interrupts' should
show the device drivers has two interrupt entries for each port.  Run I/O
tests.  Then 'lspci -vv' should display the correct pci capabilities for the
installed adapter and show the adapter is using MSI-X interrupts opposed to MSO
or LSI interrupts.

===============================================================
Ameet Paranjape 978-392-3903 ext 23903
IBM on-site partner

Proposed Patch:
===============

diff --git a/arch/powerpc/kernel/msi-rtas.c b/arch/powerpc/kernel/msi-rtas.c
index 9de7a33..270caa8 100644
--- a/arch/powerpc/kernel/msi-rtas.c
+++ b/arch/powerpc/kernel/msi-rtas.c
@@ -357,6 +357,27 @@ static int rtas_msi_check_device(struct pci_dev *pdev, int nvec, int type)
 	return 0;
 }
 
+static int check_msix_entries(struct pci_dn *pdn)
+{
+	struct msi_desc *entry;
+	int expected;
+
+	/* There's no way for us to express to firmware that we want
+	 * a discontiguous, or non-zero based, range of MSI-X entries.
+	 * So we must reject such requests. */
+
+	expected = 0;
+	list_for_each_entry(entry, &pdn->msi_list, list) {
+		if (entry->msi_attrib.entry_nr != expected) {
+			pr_debug("rtas_msi: bad MSI-X entries.\n");
+			return -EINVAL;
+		}
+		expected++;
+	}
+
+	return 0;
+}
+
 static int rtas_setup_msi_irqs(struct pci_dev *pdev, int nvec, int type)
 {
 	struct pci_dn *pdn;
@@ -368,6 +389,9 @@ static int rtas_setup_msi_irqs(struct pci_dev *pdev, int nvec, int type)
 	if (!pdn)
 		return -ENODEV;
 
+	if (type == PCI_CAP_ID_MSIX && check_msix_entries(pdev))
+		return -EINVAL;
+
 	/*
 	 * Try the new more explicit firmware interface, if that fails fall
 	 * back to the old interface. The old interface is known to never