refactor(cpufeat): enable FEAT_NV2 for FEAT_STATE_CHECKED
At the moment we only support for FEAT_NV2 to be either unconditionally
compiled in, or to be not supported at all.
Add support for runtime detection (CTX_INCLUDE_NEVE_REGS=2), by
splitting get_armv8_4_feat_nv_support() into an ID register reading
function and a second function to report the support status. That
function considers both build time settings and runtime information
(if needed), and is used before we access the VNCR_EL2 system register.
Also move the context saving code from assembly to C, and use the new
is_feat_nv2_supported() function to guard its execution.
Change the FVP platform default to the now supported dynamic option (=2),
so the right decision can be made by the code at runtime.
Change-Id: I85b080641995fb72cfd4ac933f7a3f75770c2cb9
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
diff --git a/include/arch/aarch64/arch_features.h b/include/arch/aarch64/arch_features.h
index fa80154..72927fb 100644
--- a/include/arch/aarch64/arch_features.h
+++ b/include/arch/aarch64/arch_features.h
@@ -423,10 +423,22 @@
* Function to identify the presence of FEAT_NV2 (Enhanced Nested Virtualization
* Support)
*******************************************************************************/
-static inline unsigned int get_armv8_4_feat_nv_support(void)
+static inline unsigned int read_feat_nv_id_field(void)
{
- return (((read_id_aa64mmfr2_el1() >> ID_AA64MMFR2_EL1_NV_SHIFT) &
- ID_AA64MMFR2_EL1_NV_MASK));
+ return ISOLATE_FIELD(read_id_aa64mmfr2_el1(), ID_AA64MMFR2_EL1_NV);
+}
+
+static inline bool is_feat_nv2_supported(void)
+{
+ if (CTX_INCLUDE_NEVE_REGS == FEAT_STATE_DISABLED) {
+ return false;
+ }
+
+ if (CTX_INCLUDE_NEVE_REGS == FEAT_STATE_ALWAYS) {
+ return true;
+ }
+
+ return read_feat_nv_id_field() >= ID_AA64MMFR2_EL1_NV2_SUPPORTED;
}
/*******************************************************************************