Similarly to QemuFwCfgLib, we prefer mellow library construction code and
an explicit "are you available" query function in the XenHypercallLib
class. In this step we introduce that query function, but move no client
code to it yet.
Suggested-by: Jordan Justen <jordan.l.jus...@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <ler...@redhat.com>
---
OvmfPkg/Include/Library/XenHypercallLib.h | 16 ++++++++++++++++
OvmfPkg/Library/XenHypercallLib/ArmXenHypercall.c | 19 +++++++++++++++++++
OvmfPkg/Library/XenHypercallLib/X86XenHypercall.c | 19 +++++++++++++++++++
3 files changed, 54 insertions(+)
diff --git a/OvmfPkg/Include/Library/XenHypercallLib.h
b/OvmfPkg/Include/Library/XenHypercallLib.h
index 1a468ea..509855d 100644
--- a/OvmfPkg/Include/Library/XenHypercallLib.h
+++ b/OvmfPkg/Include/Library/XenHypercallLib.h
@@ -17,6 +17,22 @@
#define __XEN_HYPERCALL_LIB_H__
/**
+ Check if the Xen Hypercall library is able to make calls to the Xen
+ hypervisor.
+
+ Client code should call further functions in this library only if, and after,
+ this function returns TRUE.
+
+ @retval TRUE Hypercalls are available.
+ @retval FALSE Hypercalls are not available.
+**/
+BOOLEAN
+EFIAPI
+XenHypercallIsAvailable (
+ VOID
+ );
+
+/**
This function will put the two arguments in the right place (registers) and
invoke the hypercall identified by HypercallID.
diff --git a/OvmfPkg/Library/XenHypercallLib/ArmXenHypercall.c
b/OvmfPkg/Library/XenHypercallLib/ArmXenHypercall.c
index 56cc2f6..99a3170 100644
--- a/OvmfPkg/Library/XenHypercallLib/ArmXenHypercall.c
+++ b/OvmfPkg/Library/XenHypercallLib/ArmXenHypercall.c
@@ -15,6 +15,25 @@
#include <Base.h>
+/**
+ Check if the Xen Hypercall library is able to make calls to the Xen
+ hypervisor.
+
+ Client code should call further functions in this library only if, and after,
+ this function returns TRUE.
+
+ @retval TRUE Hypercalls are available.
+ @retval FALSE Hypercalls are not available.
+**/
+BOOLEAN
+EFIAPI
+XenHypercallIsAvailable (
+ VOID
+ )
+{
+ return TRUE;
+}
+
RETURN_STATUS
EFIAPI
ArmXenHypercallLibInit (
diff --git a/OvmfPkg/Library/XenHypercallLib/X86XenHypercall.c
b/OvmfPkg/Library/XenHypercallLib/X86XenHypercall.c
index 3ca05c7..14fa175 100644
--- a/OvmfPkg/Library/XenHypercallLib/X86XenHypercall.c
+++ b/OvmfPkg/Library/XenHypercallLib/X86XenHypercall.c
@@ -19,6 +19,25 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER
EXPRESS OR IMPLIED.
STATIC VOID *HyperPage;
+/**
+ Check if the Xen Hypercall library is able to make calls to the Xen
+ hypervisor.
+
+ Client code should call further functions in this library only if, and after,
+ this function returns TRUE.
+
+ @retval TRUE Hypercalls are available.
+ @retval FALSE Hypercalls are not available.
+**/
+BOOLEAN
+EFIAPI
+XenHypercallIsAvailable (
+ VOID
+ )
+{
+ return HyperPage != NULL;
+}
+
//
// Interface exposed by the ASM implementation of the core hypercall
//
--
1.8.3.1
------------------------------------------------------------------------------
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