[xen staging] xen/riscv: introduce nospec.h

[patchbot@xxxxxxx]

commit 7159164beeb582cb57a3142744d747daae7d59b9
Author:     Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
AuthorDate: Thu Feb 29 16:58:34 2024 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Feb 29 16:58:34 2024 +0100

    xen/riscv: introduce nospec.h
    
    From the unpriviliged doc:
      No standard hints are presently defined.
      We anticipate standard hints to eventually include memory-system spatial
      and temporal locality hints, branch prediction hints, thread-scheduling
      hints, security tags, and instrumentation flags for simulation/emulation.
    
    Also, there are no speculation execution barriers.
    
    Therefore, functions evaluate_nospec() and block_speculation() should
    remain empty until a specific platform has an extension to deal with
    speculation execution.
    
    Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
    Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/arch/riscv/include/asm/nospec.h | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/xen/arch/riscv/include/asm/nospec.h 
b/xen/arch/riscv/include/asm/nospec.h
new file mode 100644
index 0000000000..e30f0a781b
--- /dev/null
+++ b/xen/arch/riscv/include/asm/nospec.h
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* Copyright (C) 2024 Vates */
+
+#ifndef _ASM_RISCV_NOSPEC_H
+#define _ASM_RISCV_NOSPEC_H
+
+static inline bool evaluate_nospec(bool condition)
+{
+    return condition;
+}
+
+static inline void block_speculation(void)
+{
+}
+
+#endif /* _ASM_RISCV_NOSPEC_H */
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
--
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