x86/HVM: expose that grant table mappings update the IOMMU

Add a new CPUID flag for leaf 4 that indicates that grant/foreign
mappings update the IOMMU accordingly.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index d2c6942b64dfa5f2588e8bdbeb68552c853779f3..d40c48ed7e27e271d071eb76760f205f6f79059d 100644 (file)
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -67,6 +67,7 @@
 #include <asm/mem_access.h>
 #include <public/mem_event.h>
 #include <xen/rangeset.h>
+#include <public/arch-x86/cpuid.h>
 
 bool_t __read_mostly hvm_enabled;
 
@@ -4197,6 +4198,15 @@ void hvm_hypervisor_cpuid_leaf(uint32_t sub_idx,
     *eax = *ebx = *ecx = *edx = 0;
     if ( hvm_funcs.hypervisor_cpuid_leaf )
         hvm_funcs.hypervisor_cpuid_leaf(sub_idx, eax, ebx, ecx, edx);
+
+    if ( sub_idx == 0 )
+    {
+        /*
+         * Indicate that memory mapped from other domains (either grants or
+         * foreign pages) has valid IOMMU entries.
+         */
+        *eax |= XEN_HVM_CPUID_IOMMU_MAPPINGS;
+    }
 }
 
 void hvm_cpuid(unsigned int input, unsigned int *eax, unsigned int *ebx,

diff --git a/xen/include/public/arch-x86/cpuid.h b/xen/include/public/arch-x86/cpuid.h
index 7135d5456bfd954a57b71b59023e2fb21e31e691..e57a4578e5930e0f3055793a9e2789fb5913e9c9 100644 (file)
--- a/xen/include/public/arch-x86/cpuid.h
+++ b/xen/include/public/arch-x86/cpuid.h
@@ -73,6 +73,8 @@
 /* EAX Features */
 #define XEN_HVM_CPUID_APIC_ACCESS_VIRT (1u << 0) /* Virtualized APIC registers */
 #define XEN_HVM_CPUID_X2APIC_VIRT      (1u << 1) /* Virtualized x2APIC accesses */
+/* Memory mapped from other domains has valid IOMMU entries */
+#define XEN_HVM_CPUID_IOMMU_MAPPINGS   (1u << 2)
 
 #define XEN_CPUID_MAX_NUM_LEAVES 4