From: Jan Beulich <jbeulich@suse.com>
Date: Wed, 16 Sep 2015 09:20:27 +0000 (+0200)
Subject: x86/MSI: fail if no hardware support
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~2534
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=c7d5d5d8ea1ecbd6ef8b47dace4dec825f0f6e48;p=xen.git

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@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
---

diff --git a/xen/arch/x86/msi.c b/xen/arch/x86/msi.c
index 588305ab9f..3dbb84ddac 100644
--- a/xen/arch/x86/msi.c
+++ b/xen/arch/x86/msi.c
@@ -696,6 +696,8 @@ 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 )