[Xen-changelog] [xen stable-4.4] x86/MSI: fail if no hardware support

[patchbot@xxxxxxx]

commit 55d626318e9047cd38e1252906e1fbca123a5068
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Thu Oct 8 12:42:50 2015 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Oct 8 12:42:50 2015 +0200

    x86/MSI: fail if no hardware support
    
    This is to guard against buggy callers (luckily Dom0 only) invoking
    the respective hypercall for a device not being MSI-capable.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    master commit: c7d5d5d8ea1ecbd6ef8b47dace4dec825f0f6e48
    master date: 2015-09-16 11:20:27 +0200
---
 xen/arch/x86/msi.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/xen/arch/x86/msi.c b/xen/arch/x86/msi.c
index 32a2594..13a17bf 100644
--- a/xen/arch/x86/msi.c
+++ b/xen/arch/x86/msi.c
@@ -566,6 +566,8 @@ static int msi_capability_init(struct pci_dev *dev,
 
     ASSERT(spin_is_locked(&pcidevs_lock));
     pos = pci_find_cap_offset(seg, bus, slot, func, PCI_CAP_ID_MSI);
+    if ( !pos )
+        return -ENODEV;
     control = pci_conf_read16(seg, bus, slot, func, msi_control_reg(pos));
     maxvec = multi_msi_capable(control);
     if ( nvec > maxvec )
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.4

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