From af0bd66187545a26d5b136eb29a0bf7b877a1b5c Mon Sep 17 00:00:00 2001
From: Paul Durrant <pdurrant@amazon.com>
Date: Fri, 27 Nov 2020 08:41:33 +0000
Subject: [PATCH] Add a new helper function to make VCPUOP_register_vcpu_info
 hypercalls

Signed-off-by: Paul Durrant <pdurrant@amazon.com>
---
 include/xen.h  |  9 +++++++++
 src/xen/vcpu.c | 38 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 47 insertions(+)

diff --git a/include/xen.h b/include/xen.h
index 89f6886..8fb55c7 100644
--- a/include/xen.h
+++ b/include/xen.h
@@ -495,4 +495,13 @@ VcpuSetPeriodicTimer(
     IN  PLARGE_INTEGER  Period
     );
 
+__checkReturn
+XEN_API
+NTSTATUS
+VcpuRegisterVcpuInfo(
+    IN  unsigned int                vcpu_id,
+    IN  PFN_NUMBER                  Pfn,
+    IN  ULONG                       Offset
+    );
+
 #endif  // _XEN_H
diff --git a/src/xen/vcpu.c b/src/xen/vcpu.c
index a1881cf..552b3b3 100644
--- a/src/xen/vcpu.c
+++ b/src/xen/vcpu.c
@@ -80,3 +80,41 @@ fail1:
 
     return status;
 }
+
+__checkReturn
+XEN_API
+NTSTATUS
+VcpuRegisterVcpuInfo(
+    IN  unsigned int                vcpu_id,
+    IN  PFN_NUMBER                  Pfn,
+    IN  ULONG                       Offset
+    )
+{
+    struct vcpu_register_vcpu_info  op;
+    LONG_PTR                        rc;
+    NTSTATUS                        status;
+
+    op.mfn = (xen_pfn_t)Pfn;
+    op.offset = Offset;
+    op.rsvd = 0;
+
+    //
+    // NOTE: This has to be called on the CPU with the matching vcpu_id
+    //       otherwise Xen will fail the hypercall with -EINVAL.
+    //
+
+    rc = VcpuOp(VCPUOP_register_vcpu_info, vcpu_id, &op);
+
+    if (rc < 0) {
+        ERRNO_TO_STATUS(-rc, status);
+        goto fail1;
+    }
+
+    return STATUS_SUCCESS;
+
+fail1:
+    Error("fail1 (%08x)\n", status);
+
+    return status;
+
+}
-- 
2.39.5