xen/x86: report domain id on cpuid

Use the ECX register of the hypervisor leaf 5. The EAX register on
this leaf is a flags field that can be used to notice the presence of
the domain id in ECX. Note that this is only available to HVM guests.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
---
Changes since v1:
 - Use leaf 5 instead.

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 68b684bed0f2c5edbf7cffec0478d5f54b195cc0..1a06345dbc03c5415d6107b221e907732350c9e3 100644 (file)
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -3479,6 +3479,11 @@ void hvm_hypervisor_cpuid_leaf(uint32_t sub_idx,
         /* Indicate presence of vcpu id and set it in ebx */
         *eax |= XEN_HVM_CPUID_VCPU_ID_PRESENT;
         *ebx = current->vcpu_id;
+
+        /* Indicate presence of domain id and set it on ecx */
+        *eax |= XEN_HVM_CPUID_DOMID_PRESENT;
+        *ecx = current->domain->domain_id;
+
     }
 }
 

diff --git a/xen/include/public/arch-x86/cpuid.h b/xen/include/public/arch-x86/cpuid.h
index d709340f18d089560b959835eabb7b6609542c7e..634d6aa5716f18049d800ec772ae2d5a9d1e3edd 100644 (file)
--- a/xen/include/public/arch-x86/cpuid.h
+++ b/xen/include/public/arch-x86/cpuid.h
@@ -78,12 +78,14 @@
  * HVM-specific features
  * EAX: Features
  * EBX: vcpu id (iff EAX has XEN_HVM_CPUID_VCPU_ID_PRESENT flag)
+ * ECX: domain id (iff EAX has XEN_HVM_CPUID_DOMID_PRESENT flag)
  */
 #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_HVM_CPUID_VCPU_ID_PRESENT  (1u << 3) /* vcpu id is present in EBX */
+#define XEN_HVM_CPUID_DOMID_PRESENT    (1u << 4) /* domid is present in ECX */
 
 #define XEN_CPUID_MAX_NUM_LEAVES 4