[Xen-devel] [PATCH v6 09/11] x86/hyperv: retrieve vp_index from Hyper-V

[Wei Liu <wl@xxxxxxx>]

This will be useful when invoking hypercall that targets specific
vcpu(s).

Signed-off-by: Wei Liu <liuwe@xxxxxxxxxxxxx>
Reviewed-by: Paul Durrant <paul@xxxxxxx>
Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
---
v5:
1. Add Jan's Ack.

v4:
1. Use private.h
2. Add Paul's review tag

v2:
1. Fold into setup_pcpu_arg function
---
 xen/arch/x86/guest/hyperv/hyperv.c  | 6 ++++++
 xen/arch/x86/guest/hyperv/private.h | 1 +
 2 files changed, 7 insertions(+)

diff --git a/xen/arch/x86/guest/hyperv/hyperv.c 
b/xen/arch/x86/guest/hyperv/hyperv.c
index 8d44b35aa6..6dac3bfceb 100644
--- a/xen/arch/x86/guest/hyperv/hyperv.c
+++ b/xen/arch/x86/guest/hyperv/hyperv.c
@@ -31,6 +31,7 @@
 
 struct ms_hyperv_info __read_mostly ms_hyperv;
 DEFINE_PER_CPU_READ_MOSTLY(void *, hv_input_page);
+DEFINE_PER_CPU_READ_MOSTLY(unsigned int, hv_vp_index);
 
 static uint64_t generate_guest_id(void)
 {
@@ -135,6 +136,8 @@ static void __init setup_hypercall_page(void)
 
 static int setup_hypercall_pcpu_arg(void)
 {
+    uint64_t vp_index_msr;
+
     if ( this_cpu(hv_input_page) )
         return 0;
 
@@ -146,6 +149,9 @@ static int setup_hypercall_pcpu_arg(void)
         return -ENOMEM;
     }
 
+    rdmsrl(HV_X64_MSR_VP_INDEX, vp_index_msr);
+    this_cpu(hv_vp_index) = vp_index_msr;
+
     return 0;
 }
 
diff --git a/xen/arch/x86/guest/hyperv/private.h 
b/xen/arch/x86/guest/hyperv/private.h
index 093985a94b..d1765d4f23 100644
--- a/xen/arch/x86/guest/hyperv/private.h
+++ b/xen/arch/x86/guest/hyperv/private.h
@@ -25,5 +25,6 @@
 #include <xen/percpu.h>
 
 DECLARE_PER_CPU(void *, hv_input_page);
+DECLARE_PER_CPU(unsigned int, hv_vp_index);
 
 #endif /* __XEN_HYPERV_PRIVIATE_H__  */
-- 
2.20.1


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