[Xen-devel] [PATCH v15 02/11] x86: add generic resource (e.g. MSR) access hypercall

[Chao Peng <chao.p.peng@xxxxxxxxxxxxxxx>]

Add a generic resource access hypercall for tool stack or other
components, e.g., accessing MSR, port I/O, etc.

Signed-off-by: Dongxiao Xu <dongxiao.xu@xxxxxxxxx>
Signed-off-by: Chao Peng <chao.p.peng@xxxxxxxxxxxxxxx>
---
 xen/arch/x86/platform_hypercall.c |   63 +++++++++++++++++++++++++++++++++++++
 xen/include/public/platform.h     |   15 +++++++++
 xen/include/xlat.lst              |    1 +
 3 files changed, 79 insertions(+)

diff --git a/xen/arch/x86/platform_hypercall.c 
b/xen/arch/x86/platform_hypercall.c
index 2162811..e5ad4c9 100644
--- a/xen/arch/x86/platform_hypercall.c
+++ b/xen/arch/x86/platform_hypercall.c
@@ -61,6 +61,42 @@ long cpu_down_helper(void *data);
 long core_parking_helper(void *data);
 uint32_t get_cur_idle_nums(void);
 
+struct xen_resource_access {
+    int32_t ret;
+    struct xenpf_resource_op *data;
+};
+
+static bool_t allow_access_msr(unsigned int msr)
+{
+    return 0;
+}
+
+static void resource_access_one(void *info)
+{
+    struct xen_resource_access *ra = info;
+    int ret = 0;
+
+    switch ( ra->data->cmd )
+    {
+    case XEN_RESOURCE_OP_MSR_READ:
+    case XEN_RESOURCE_OP_MSR_WRITE:
+        if ( ra->data->idx >> 32 )
+            ret = -EINVAL;
+        else if ( !allow_access_msr(ra->data->idx) )
+            ret = -EACCES;
+        else if ( ra->data->cmd == XEN_RESOURCE_OP_MSR_READ )
+            ret = rdmsr_safe(ra->data->idx, ra->data->val);
+        else
+            ret = wrmsr_safe(ra->data->idx, ra->data->val);
+        break;
+    default:
+        ret = -EINVAL;
+        break;
+    }
+
+    ra->ret = ret;
+}
+
 ret_t do_platform_op(XEN_GUEST_HANDLE_PARAM(xen_platform_op_t) u_xenpf_op)
 {
     ret_t ret = 0;
@@ -601,6 +637,33 @@ ret_t 
do_platform_op(XEN_GUEST_HANDLE_PARAM(xen_platform_op_t) u_xenpf_op)
     }
     break;
 
+    case XENPF_resource_op:
+    {
+        struct xen_resource_access ra;
+        struct xenpf_resource_op *rsc_op = &op->u.resource_op;
+        unsigned int cpu = smp_processor_id();
+
+        ra.data = rsc_op;
+
+        if ( rsc_op->cpu == cpu )
+            resource_access_one(&ra);
+        else if ( cpu_online(rsc_op->cpu) )
+            on_selected_cpus(cpumask_of(rsc_op->cpu),
+                         resource_access_one, &ra, 1);
+        else
+        {
+            ret = -ENODEV;
+            break;
+        }
+
+        if ( ra.ret )
+        {
+            ret = ra.ret;
+            break;
+        }
+    }
+    break;
+
     default:
         ret = -ENOSYS;
         break;
diff --git a/xen/include/public/platform.h b/xen/include/public/platform.h
index 053b9fa..3ed50de 100644
--- a/xen/include/public/platform.h
+++ b/xen/include/public/platform.h
@@ -527,6 +527,20 @@ struct xenpf_core_parking {
 typedef struct xenpf_core_parking xenpf_core_parking_t;
 DEFINE_XEN_GUEST_HANDLE(xenpf_core_parking_t);
 
+#define XENPF_resource_op   61
+
+#define XEN_RESOURCE_OP_MSR_READ  0
+#define XEN_RESOURCE_OP_MSR_WRITE 1
+
+struct xenpf_resource_op {
+    uint16_t cmd;       /* XEN_RESOURCE_OP_* */
+    uint32_t cpu;
+    uint64_t idx;
+    uint64_t val;
+};
+typedef struct xenpf_resource_op xenpf_resource_op_t;
+DEFINE_XEN_GUEST_HANDLE(xenpf_resource_op_t);
+
 /*
  * ` enum neg_errnoval
  * ` HYPERVISOR_platform_op(const struct xen_platform_op*);
@@ -553,6 +567,7 @@ struct xen_platform_op {
         struct xenpf_cpu_hotadd        cpu_add;
         struct xenpf_mem_hotadd        mem_add;
         struct xenpf_core_parking      core_parking;
+        struct xenpf_resource_op       resource_op;
         uint8_t                        pad[128];
     } u;
 };
diff --git a/xen/include/xlat.lst b/xen/include/xlat.lst
index 9a35dd7..06ed7b9 100644
--- a/xen/include/xlat.lst
+++ b/xen/include/xlat.lst
@@ -88,6 +88,7 @@
 ?      xenpf_enter_acpi_sleep          platform.h
 ?      xenpf_pcpuinfo                  platform.h
 ?      xenpf_pcpu_version              platform.h
+?      xenpf_resource_op               platform.h
 !      sched_poll                      sched.h
 ?      sched_remote_shutdown           sched.h
 ?      sched_shutdown                  sched.h
-- 
1.7.9.5


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