[RFC PATCH 14/14] HACK: Accept prototype RSI version

[Steven Price]

The upstream RMM currently advertises the major version of an internal
prototype (v12.0) rather than the expected version from the RMM
architecture specification (v1.0).

Add a config option to enable support for the prototype RSI v12.0.

Signed-off-by: Steven Price <steven.price@xxxxxxx>
---
 arch/arm64/include/asm/rsi_smc.h | 2 ++
 arch/arm64/kernel/rsi.c          | 5 +++++
 arch/arm64/kvm/Kconfig           | 8 ++++++++
 3 files changed, 15 insertions(+)

diff --git a/arch/arm64/include/asm/rsi_smc.h b/arch/arm64/include/asm/rsi_smc.h
index bc0cdd83f164..baf07f905353 100644
--- a/arch/arm64/include/asm/rsi_smc.h
+++ b/arch/arm64/include/asm/rsi_smc.h
@@ -29,6 +29,8 @@
 #define RSI_ABI_VERSION			((RSI_ABI_VERSION_MAJOR << 16) | \
 					 RSI_ABI_VERSION_MINOR)
 
+#define RSI_LEGACY_ABI_VERSION		0xc0000
+
 #define RSI_ABI_VERSION_GET_MAJOR(_version) ((_version) >> 16)
 #define RSI_ABI_VERSION_GET_MINOR(_version) ((_version) & 0xFFFF)
 
diff --git a/arch/arm64/kernel/rsi.c b/arch/arm64/kernel/rsi.c
index 1cc292826f2b..45b26f23e706 100644
--- a/arch/arm64/kernel/rsi.c
+++ b/arch/arm64/kernel/rsi.c
@@ -41,6 +41,11 @@ static bool rsi_version_matches(void)
 		RSI_ABI_VERSION_GET_MAJOR(ver),
 		RSI_ABI_VERSION_GET_MINOR(ver));
 
+#ifdef CONFIG_RME_USE_PROTOTYPE_HACKS
+	if (ver == RSI_LEGACY_ABI_VERSION)
+		return true;
+#endif
+
 	return (ver >= RSI_ABI_VERSION &&
 		RSI_ABI_VERSION_GET_MAJOR(ver) == RSI_ABI_VERSION_MAJOR);
 }
diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
index 05da3c8f7e88..13858a5047fd 100644
--- a/arch/arm64/kvm/Kconfig
+++ b/arch/arm64/kvm/Kconfig
@@ -58,6 +58,14 @@ config NVHE_EL2_DEBUG
 
 	  If unsure, say N.
 
+config RME_USE_PROTOTYPE_HACKS
+	bool "Allow RMM prototype version numbers"
+	default y
+	help
+	  For compatibility with the the current RMM code allow versions
+	  numbers from a prototype implementation as well as the expected
+	  version number from the RMM specification.
+
 config PROTECTED_NVHE_STACKTRACE
 	bool "Protected KVM hypervisor stacktraces"
 	depends on NVHE_EL2_DEBUG
-- 
2.34.1