[Xen-changelog] [xen master] x86/hvm: extend HVM cpuid leaf with vcpu id

[patchbot@xxxxxxx]

commit dd9b0922663751cf3484f0e141ba887422ed15ec
Author:     Paul Durrant <paul.durrant@xxxxxxxxxx>
AuthorDate: Wed Jan 7 11:08:49 2015 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed Jan 7 11:08:49 2015 +0100

    x86/hvm: extend HVM cpuid leaf with vcpu id
    
    To perform certain hypercalls HVM guests need to use Xen's idea of
    vcpu id, which may well not match the guest OS idea of CPU id.
    This patch adds vcpu id to the HVM cpuid leaf allowing the guest
    to build a mapping.
    
    Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/arch/x86/hvm/hvm.c              |    4 ++++
 xen/include/public/arch-x86/cpuid.h |    5 +++--
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 72be5b9..e33cd0a 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -4188,6 +4188,10 @@ void hvm_hypervisor_cpuid_leaf(uint32_t sub_idx,
          * foreign pages) has valid IOMMU entries.
          */
         *eax |= XEN_HVM_CPUID_IOMMU_MAPPINGS;
+
+        /* Indicate presence of vcpu id and set it in ebx */
+        *eax |= XEN_HVM_CPUID_VCPU_ID_PRESENT;
+        *ebx = current->vcpu_id;
     }
 }
 
diff --git a/xen/include/public/arch-x86/cpuid.h 
b/xen/include/public/arch-x86/cpuid.h
index 6005dfe..d709340 100644
--- a/xen/include/public/arch-x86/cpuid.h
+++ b/xen/include/public/arch-x86/cpuid.h
@@ -76,13 +76,14 @@
 /*
  * Leaf 5 (0x40000x04)
  * HVM-specific features
+ * EAX: Features
+ * EBX: vcpu id (iff EAX has XEN_HVM_CPUID_VCPU_ID_PRESENT flag)
  */
-
-/* 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_HVM_CPUID_VCPU_ID_PRESENT  (1u << 3) /* vcpu id is present in EBX 
*/
 
 #define XEN_CPUID_MAX_NUM_LEAVES 4
 
--
generated by git-patchbot for /home/xen/git/xen.git#master

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