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62 lines
2.0 KiB
62 lines
2.0 KiB
From e3de4a44cfe196e162ddeffd6379e5c4e75ff1d7 Mon Sep 17 00:00:00 2001
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From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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Date: Fri, 3 Apr 2015 11:08:22 -0400
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Subject: [PATCH v2 XSA157 1/5] xen/pciback: Return error on
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XEN_PCI_OP_enable_msi when device has MSI or MSI-X enabled
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The guest sequence of:
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a) XEN_PCI_OP_enable_msi
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b) XEN_PCI_OP_enable_msi
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c) XEN_PCI_OP_disable_msi
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results in hitting an BUG_ON condition in the msi.c code.
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The MSI code uses an dev->msi_list to which it adds MSI entries.
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Under the above conditions an BUG_ON() can be hit. The device
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passed in the guest MUST have MSI capability.
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The a) adds the entry to the dev->msi_list and sets msi_enabled.
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The b) adds a second entry but adding in to SysFS fails (duplicate entry)
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and deletes all of the entries from msi_list and returns (with msi_enabled
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is still set). c) pci_disable_msi passes the msi_enabled checks and hits:
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BUG_ON(list_empty(dev_to_msi_list(&dev->dev)));
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and blows up.
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The patch adds a simple check in the XEN_PCI_OP_enable_msi to guard
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against that. The check for msix_enabled is not stricly neccessary.
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This is part of XSA-157.
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CC: stable@vger.kernel.org
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Reviewed-by: David Vrabel <david.vrabel@citrix.com>
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Reviewed-by: Jan Beulich <jbeulich@suse.com>
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Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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---
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drivers/xen/xen-pciback/pciback_ops.c | 7 ++++++-
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1 file changed, 6 insertions(+), 1 deletion(-)
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diff --git a/drivers/xen/xen-pciback/pciback_ops.c b/drivers/xen/xen-pciback/pciback_ops.c
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index c4a0666..5ce573a 100644
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--- a/drivers/xen/xen-pciback/pciback_ops.c
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+++ b/drivers/xen/xen-pciback/pciback_ops.c
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@@ -144,7 +144,12 @@ int xen_pcibk_enable_msi(struct xen_pcibk_device *pdev,
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if (unlikely(verbose_request))
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printk(KERN_DEBUG DRV_NAME ": %s: enable MSI\n", pci_name(dev));
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- status = pci_enable_msi(dev);
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+ if (dev->msi_enabled)
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+ status = -EALREADY;
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+ else if (dev->msix_enabled)
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+ status = -ENXIO;
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+ else
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+ status = pci_enable_msi(dev);
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if (status) {
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pr_warn_ratelimited("%s: error enabling MSI for guest %u: err %d\n",
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--
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2.1.0
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