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| Started by | Ben Hutchings <ben@decadent.org.uk> |
|---|---|
| First post | 2016-01-18 04:30 +0100 |
| Last post | 2016-01-18 04:30 +0100 |
| Articles | 1 — 1 participant |
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[PATCH 3.2 25/70] xen/pciback: Return error on XEN_PCI_OP_enable_msi when device has MSI or MSI-X enabled Ben Hutchings <ben@decadent.org.uk> - 2016-01-18 04:30 +0100
| From | Ben Hutchings <ben@decadent.org.uk> |
|---|---|
| Date | 2016-01-18 04:30 +0100 |
| Subject | [PATCH 3.2 25/70] xen/pciback: Return error on XEN_PCI_OP_enable_msi when device has MSI or MSI-X enabled |
| Message-ID | <qS8FY-3hu-7@gated-at.bofh.it> |
3.2.76-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
commit 56441f3c8e5bd45aab10dd9f8c505dd4bec03b0d upstream.
The guest sequence of:
a) XEN_PCI_OP_enable_msi
b) XEN_PCI_OP_enable_msi
c) XEN_PCI_OP_disable_msi
results in hitting an BUG_ON condition in the msi.c code.
The MSI code uses an dev->msi_list to which it adds MSI entries.
Under the above conditions an BUG_ON() can be hit. The device
passed in the guest MUST have MSI capability.
The a) adds the entry to the dev->msi_list and sets msi_enabled.
The b) adds a second entry but adding in to SysFS fails (duplicate entry)
and deletes all of the entries from msi_list and returns (with msi_enabled
is still set). c) pci_disable_msi passes the msi_enabled checks and hits:
BUG_ON(list_empty(dev_to_msi_list(&dev->dev)));
and blows up.
The patch adds a simple check in the XEN_PCI_OP_enable_msi to guard
against that. The check for msix_enabled is not stricly neccessary.
This is part of XSA-157.
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/xen/xen-pciback/pciback_ops.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
--- a/drivers/xen/xen-pciback/pciback_ops.c
+++ b/drivers/xen/xen-pciback/pciback_ops.c
@@ -142,7 +142,12 @@ int xen_pcibk_enable_msi(struct xen_pcib
if (unlikely(verbose_request))
printk(KERN_DEBUG DRV_NAME ": %s: enable MSI\n", pci_name(dev));
- status = pci_enable_msi(dev);
+ if (dev->msi_enabled)
+ status = -EALREADY;
+ else if (dev->msix_enabled)
+ status = -ENXIO;
+ else
+ status = pci_enable_msi(dev);
if (status) {
pr_warn_ratelimited(DRV_NAME ": %s: error enabling MSI for guest %u: err %d\n",
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