| From d95b065f260e169d383f9086172a31df6d0b4004 Mon Sep 17 00:00:00 2001 |
| From: Dan Streetman <ddstreet@ieee.org> |
| Date: Fri, 13 Jan 2017 15:07:51 -0500 |
| Subject: [PATCH] xen: do not re-use pirq number cached in pci device msi msg |
| data |
| |
| commit c74fd80f2f41d05f350bb478151021f88551afe8 upstream. |
| |
| 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: Paul Gortmaker <paul.gortmaker@windriver.com> |
| |
| diff --git a/arch/x86/pci/xen.c b/arch/x86/pci/xen.c |
| index 3a483cb5ac81..4ea9f290c19f 100644 |
| --- a/arch/x86/pci/xen.c |
| +++ b/arch/x86/pci/xen.c |
| @@ -234,23 +234,14 @@ static int xen_hvm_setup_msi_irqs(struct pci_dev *dev, int nvec, int type) |
| 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) ? |
| -- |
| 2.12.0 |
| |