[Xen-devel] [PATCH v2 02/62] xen/x86: report domain id on cpuid

[Wei Liu <wei.liu2@xxxxxxxxxx>]

From: Roger Pau Monne <roger.pau@xxxxxxxxxx>

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@xxxxxxxxxx>
---
Changes since v1:
 - Use leaf 5 instead.
---
 xen/arch/x86/traps.c                | 5 +++++
 xen/include/public/arch-x86/cpuid.h | 2 ++
 2 files changed, 7 insertions(+)

diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index db16a44417..a896053b2f 100644
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -924,6 +924,11 @@ void cpuid_hypervisor_leaves(const struct vcpu *v, 
uint32_t leaf,
         /* Indicate presence of vcpu id and set it in ebx */
         res->a |= XEN_HVM_CPUID_VCPU_ID_PRESENT;
         res->b = v->vcpu_id;
+
+        /* Indicate presence of domain id and set it in ecx */
+        res->a |= XEN_HVM_CPUID_DOMID_PRESENT;
+        res->c = d->domain_id;
+
         break;
 
     case 5: /* PV-specific parameters */
diff --git a/xen/include/public/arch-x86/cpuid.h 
b/xen/include/public/arch-x86/cpuid.h
index eb76875d0e..665c4b644d 100644
--- a/xen/include/public/arch-x86/cpuid.h
+++ b/xen/include/public/arch-x86/cpuid.h
@@ -94,12 +94,14 @@
  * HVM-specific features
  * Sub-leaf 0: EAX: Features
  * Sub-leaf 0: EBX: vcpu id (iff EAX has XEN_HVM_CPUID_VCPU_ID_PRESENT flag)
+ * Sub-leaf 0: 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 */
 
 /*
  * Leaf 6 (0x40000x05)
-- 
2.11.0


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