[RFC 5/7] x86/iommu: the code addressing CVE-2011-1898 is VT-d specific

[Xenia Ragiadakou <burzalodowa@xxxxxxxxx>]

The variable untrusted_msi indicates whether the system is vulnerable to
CVE-2011-1898. This vulnerablity is VT-d specific.
Place the code that addresses the issue under CONFIG_INTEL_VTD.

No functional change intended.

Signed-off-by: Xenia Ragiadakou <burzalodowa@xxxxxxxxx>
---
 xen/arch/x86/include/asm/iommu.h | 2 ++
 xen/arch/x86/pv/hypercall.c      | 2 ++
 xen/arch/x86/x86_64/entry.S      | 2 ++
 3 files changed, 6 insertions(+)

diff --git a/xen/arch/x86/include/asm/iommu.h b/xen/arch/x86/include/asm/iommu.h
index fc0afe35bf..41bd1b9e05 100644
--- a/xen/arch/x86/include/asm/iommu.h
+++ b/xen/arch/x86/include/asm/iommu.h
@@ -127,7 +127,9 @@ int iommu_identity_mapping(struct domain *d, p2m_access_t 
p2ma,
                            unsigned int flag);
 void iommu_identity_map_teardown(struct domain *d);
 
+#ifdef CONFIG_INTEL_VTD
 extern bool untrusted_msi;
+#endif
 
 int pi_update_irte(const struct pi_desc *pi_desc, const struct pirq *pirq,
                    const uint8_t gvec);
diff --git a/xen/arch/x86/pv/hypercall.c b/xen/arch/x86/pv/hypercall.c
index 2eedfbfae8..0e1b03904c 100644
--- a/xen/arch/x86/pv/hypercall.c
+++ b/xen/arch/x86/pv/hypercall.c
@@ -193,8 +193,10 @@ void pv_ring1_init_hypercall_page(void *p)
 
 void do_entry_int82(struct cpu_user_regs *regs)
 {
+#ifdef CONFIG_INTEL_VTD
     if ( unlikely(untrusted_msi) )
         check_for_unexpected_msi((uint8_t)regs->entry_vector);
+#endif
 
     _pv_hypercall(regs, true /* compat */);
 }
diff --git a/xen/arch/x86/x86_64/entry.S b/xen/arch/x86/x86_64/entry.S
index ae01285181..2e06c0a6c1 100644
--- a/xen/arch/x86/x86_64/entry.S
+++ b/xen/arch/x86/x86_64/entry.S
@@ -406,11 +406,13 @@ ENTRY(int80_direct_trap)
 .Lint80_cr3_okay:
         sti
 
+#ifdef CONFIG_INTEL_VTD
         cmpb  $0,untrusted_msi(%rip)
 UNLIKELY_START(ne, msi_check)
         movl  $0x80,%edi
         call  check_for_unexpected_msi
 UNLIKELY_END(msi_check)
+#endif
 
         movq  STACK_CPUINFO_FIELD(current_vcpu)(%rbx), %rbx
 
-- 
2.37.2