x86/iommu: make code addressing CVE-2011-1898 no VT-d specific

The variable untrusted_msi indicates whether the system is vulnerable to
CVE-2011-1898 due to the absence of interrupt remapping support.
Although AMD iommus with interrupt remapping disabled are also affected,
this case is not handled yet. Given that the issue is not VT-d specific,
and to accommodate future use of the flag for covering also the AMD iommu
case, move the definition of the flag out of the VT-d specific code to the
common x86 iommu code.

Also, since the current implementation assumes that only PV guests are prone
to this attack, take the opportunity to define untrusted_msi only when PV is
enabled.

No functional change intended.

Signed-off-by: Xenia Ragiadakou <burzalodowa@gmail.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>

diff --git a/xen/drivers/passthrough/vtd/iommu.c b/xen/drivers/passthrough/vtd/iommu.c
index a9f4f28ad65c3a9e50d73468ac4867580b07066e..130a159cde0790679ed71724c4f6725fb517ab43 100644 (file)
--- a/xen/drivers/passthrough/vtd/iommu.c
+++ b/xen/drivers/passthrough/vtd/iommu.c
@@ -54,9 +54,6 @@
                                  ? dom_iommu(d)->arch.vtd.pgd_maddr \
                                  : (pdev)->arch.vtd.pgd_maddr)
 
-/* Possible unfiltered LAPIC/MSI messages from untrusted sources? */
-bool __read_mostly untrusted_msi;
-
 bool __read_mostly iommu_igfx = true;
 bool __read_mostly iommu_qinval = true;
 #ifndef iommu_snoop
@@ -2767,6 +2764,7 @@ static int cf_check reassign_device_ownership(
         if ( !has_arch_pdevs(target) )
             vmx_pi_hooks_assign(target);
 
+#ifdef CONFIG_PV
         /*
          * Devices assigned to untrusted domains (here assumed to be any domU)
          * can attempt to send arbitrary LAPIC/MSI messages. We are unprotected
@@ -2775,6 +2773,7 @@ static int cf_check reassign_device_ownership(
         if ( !iommu_intremap && !is_hardware_domain(target) &&
              !is_system_domain(target) )
             untrusted_msi = true;
+#endif
 
         ret = domain_context_mapping(target, devfn, pdev);
 

diff --git a/xen/drivers/passthrough/x86/iommu.c b/xen/drivers/passthrough/x86/iommu.c
index 5a8b28a4ca0e5bbef1418e68fd301ae986f6e96e..9c868db63b255721b6588662e0d17b06832f70d3 100644 (file)
--- a/xen/drivers/passthrough/x86/iommu.c
+++ b/xen/drivers/passthrough/x86/iommu.c
@@ -36,6 +36,11 @@ bool __initdata iommu_superpages = true;
 
 enum iommu_intremap __read_mostly iommu_intremap = iommu_intremap_full;
 
+#ifdef CONFIG_PV
+/* Possible unfiltered LAPIC/MSI messages from untrusted sources? */
+bool __read_mostly untrusted_msi;
+#endif
+
 #ifndef iommu_intpost
 /*
  * In the current implementation of VT-d posted interrupts, in some extreme