Patch "xen: do not re-use pirq number cached in pci device msi msg data" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    xen: do not re-use pirq number cached in pci device msi msg data

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     xen-do-not-re-use-pirq-number-cached-in-pci-device-msi-msg-data.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Tue Mar 28 13:59:27 CEST 2017
From: Sumit Semwal <sumit.semwal@linaro.org>
Date: Sat, 25 Mar 2017 21:48:01 +0530
Subject: xen: do not re-use pirq number cached in pci device msi msg data
To: stable@vger.kernel.org
Cc: Dan Streetman <ddstreet@ieee.org>, Dan Streetman <dan.streetman@canonical.com>, Boris Ostrovsky <boris.ostrovsky@oracle.com>, Sasha Levin <alexander.levin@verizon.com>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Sumit Semwal <sumit.semwal@linaro.org>
Message-ID: <1490458699-24484-2-git-send-email-sumit.semwal@linaro.org>

From: Sumit Semwal <sumit.semwal@linaro.org>


From: Dan Streetman <ddstreet@ieee.org>

[ Upstream commit c74fd80f2f41d05f350bb478151021f88551afe8 ]

Revert the main part of commit:
af42b8d12f8a ("xen: fix MSI setup and teardown for PV on HVM guests")

That commit introduced reading the pci device's msi message data to see
if a pirq was previously configured for the device's msi/msix, and re-use
that pirq.  At the time, that was the correct behavior.  However, a
later change to Qemu caused it to call into the Xen hypervisor to unmap
all pirqs for a pci device, when the pci device disables its MSI/MSIX
vectors; specifically the Qemu commit:
c976437c7dba9c7444fb41df45468968aaa326ad
("qemu-xen: free all the pirqs for msi/msix when driver unload")

Once Qemu added this pirq unmapping, it was no longer correct for the
kernel to re-use the pirq number cached in the pci device msi message
data.  All Qemu releases since 2.1.0 contain the patch that unmaps the
pirqs when the pci device disables its MSI/MSIX vectors.

This bug is causing failures to initialize multiple NVMe controllers
under Xen, because the NVMe driver sets up a single MSIX vector for
each controller (concurrently), and then after using that to talk to
the controller for some configuration data, it disables the single MSIX
vector and re-configures all the MSIX vectors it needs.  So the MSIX
setup code tries to re-use the cached pirq from the first vector
for each controller, but the hypervisor has already given away that
pirq to another controller, and its initialization fails.

This is discussed in more detail at:
https://lists.xen.org/archives/html/xen-devel/2017-01/msg00447.html

Fixes: af42b8d12f8a ("xen: fix MSI setup and teardown for PV on HVM guests")
Signed-off-by: Dan Streetman <dan.streetman@canonical.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/x86/pci/xen.c |   23 +++++++----------------
 1 file changed, 7 insertions(+), 16 deletions(-)

--- a/arch/x86/pci/xen.c
+++ b/arch/x86/pci/xen.c
@@ -231,23 +231,14 @@ static int xen_hvm_setup_msi_irqs(struct
 		return 1;
 
 	for_each_pci_msi_entry(msidesc, dev) {
-		__pci_read_msi_msg(msidesc, &msg);
-		pirq = MSI_ADDR_EXT_DEST_ID(msg.address_hi) |
-			((msg.address_lo >> MSI_ADDR_DEST_ID_SHIFT) & 0xff);
-		if (msg.data != XEN_PIRQ_MSI_DATA ||
-		    xen_irq_from_pirq(pirq) < 0) {
-			pirq = xen_allocate_pirq_msi(dev, msidesc);
-			if (pirq < 0) {
-				irq = -ENODEV;
-				goto error;
-			}
-			xen_msi_compose_msg(dev, pirq, &msg);
-			__pci_write_msi_msg(msidesc, &msg);
-			dev_dbg(&dev->dev, "xen: msi bound to pirq=%d\n", pirq);
-		} else {
-			dev_dbg(&dev->dev,
-				"xen: msi already bound to pirq=%d\n", pirq);
+		pirq = xen_allocate_pirq_msi(dev, msidesc);
+		if (pirq < 0) {
+			irq = -ENODEV;
+			goto error;
 		}
+		xen_msi_compose_msg(dev, pirq, &msg);
+		__pci_write_msi_msg(msidesc, &msg);
+		dev_dbg(&dev->dev, "xen: msi bound to pirq=%d\n", pirq);
 		irq = xen_bind_pirq_msi_to_irq(dev, msidesc, pirq,
 					       (type == PCI_CAP_ID_MSI) ? nvec : 1,
 					       (type == PCI_CAP_ID_MSIX) ?


Patches currently in stable-queue which might be from sumit.semwal@linaro.org are

queue-4.4/pci-add-comments-about-rom-bar-updating.patch
queue-4.4/acpi-blacklist-make-dell-latitude-3350-ethernet-work.patch
queue-4.4/s390-zcrypt-introduce-cex6-toleration.patch
queue-4.4/block-allow-write_same-commands-with-the-sg_io-ioctl.patch
queue-4.4/pci-do-any-vf-bar-updates-before-enabling-the-bars.patch
queue-4.4/x86-hyperv-handle-unknown-nmis-on-one-cpu-when-unknown_nmi_panic.patch
queue-4.4/serial-8250_pci-detach-low-level-driver-during-pci-error-recovery.patch
queue-4.4/xen-do-not-re-use-pirq-number-cached-in-pci-device-msi-msg-data.patch
queue-4.4/pci-separate-vf-bar-updates-from-standard-bar-updates.patch
queue-4.4/pci-ignore-bar-updates-on-virtual-functions.patch
queue-4.4/pci-update-bars-using-property-bits-appropriate-for-type.patch
queue-4.4/vfio-spapr-postpone-allocation-of-userspace-version-of-tce-table.patch
queue-4.4/pci-don-t-update-vf-bars-while-vf-memory-space-is-enabled.patch
queue-4.4/igb-workaround-for-igb-i210-firmware-issue.patch
queue-4.4/pci-remove-pci_resource_bar-and-pci_iov_resource_bar.patch
queue-4.4/pci-decouple-ioresource_rom_enable-and-pci_rom_address_enable.patch
queue-4.4/acpi-blacklist-add-_rev-quirks-for-dell-precision-5520-and-3520.patch
queue-4.4/igb-add-i211-to-i210-phy-workaround.patch
queue-4.4/uvcvideo-uvc_scan_fallback-for-webcams-with-broken-chain.patch