refactor(context-mgmt): move FEAT_HCX save/restore into C

At the moment we save and restore the HCRX_EL2 register in assembly, and
just depend on the build time flags.
To allow runtime checking, and to avoid too much code in assembly, move
that over to C, and use the new combined build/runtime feature check.

This also allows to drop the assert, since this should now be covered by
the different FEAT_STATE_x options.

Change-Id: I3e20b9ba17121d423cd08edc20bbf4e7ae7c0178
Signed-off-by: Andre Przywara <andre.przywara@arm.com>

4 files changed, 9 insertions, 39 deletions

diff --git a/bl31/bl31_main.c b/bl31/bl31_main.c
index a4640b1b9..e70eb5584 100644
--- a/bl31/bl31_main.c
+++ b/bl31/bl31_main.c
@@ -93,15 +93,6 @@ void bl31_setup(u_register_t arg0, u_register_t arg1, u_register_t arg2,
 	/* Perform late platform-specific setup */
 	bl31_plat_arch_setup();
 
-#if ENABLE_FEAT_HCX
-	/*
-	 * Assert that FEAT_HCX is supported on this system, without this check
-	 * an exception would occur during context save/restore if enabled but
-	 * not supported.
-	 */
-	assert(is_feat_hcx_supported());
-#endif /* ENABLE_FEAT_HCX */
-
 #if CTX_INCLUDE_PAUTH_REGS
 	/*
 	 * Assert that the ARMv8.3-PAuth registers are present or an access
diff --git a/include/lib/el3_runtime/aarch64/context.h b/include/lib/el3_runtime/aarch64/context.h
index 27cf3b947..6986e0e51 100644
--- a/include/lib/el3_runtime/aarch64/context.h
+++ b/include/lib/el3_runtime/aarch64/context.h
@@ -547,10 +547,6 @@ void el2_sysregs_context_restore_trf(el2_sysregs_t *regs);
 void el2_sysregs_context_save_csv2(el2_sysregs_t *regs);
 void el2_sysregs_context_restore_csv2(el2_sysregs_t *regs);
 #endif /* ENABLE_FEAT_CSV2_2 */
-#if ENABLE_FEAT_HCX
-void el2_sysregs_context_save_hcx(el2_sysregs_t *regs);
-void el2_sysregs_context_restore_hcx(el2_sysregs_t *regs);
-#endif /* ENABLE_FEAT_HCX */
 #endif /* CTX_INCLUDE_EL2_REGS */
 
 #if CTX_INCLUDE_FPREGS
diff --git a/lib/el3_runtime/aarch64/context.S b/lib/el3_runtime/aarch64/context.S
index e0efec2c9..a20584cc7 100644
--- a/lib/el3_runtime/aarch64/context.S
+++ b/lib/el3_runtime/aarch64/context.S
@@ -49,10 +49,6 @@
 	.global	el2_sysregs_context_save_csv2
 	.global	el2_sysregs_context_restore_csv2
 #endif /* ENABLE_FEAT_CSV2_2 */
-#if ENABLE_FEAT_HCX
-	.global	el2_sysregs_context_save_hcx
-	.global	el2_sysregs_context_restore_hcx
-#endif /* ENABLE_FEAT_HCX */
 #endif /* CTX_INCLUDE_EL2_REGS */
 
 	.global	el1_sysregs_context_save
@@ -432,19 +428,6 @@ func el2_sysregs_context_restore_csv2
 endfunc el2_sysregs_context_restore_csv2
 #endif /* ENABLE_FEAT_CSV2_2 */
 
-#if ENABLE_FEAT_HCX
-func el2_sysregs_context_save_hcx
-	mrs	x14, hcrx_el2
-	str	x14, [x0, #CTX_HCRX_EL2]
-	ret
-endfunc el2_sysregs_context_save_hcx
-
-func el2_sysregs_context_restore_hcx
-	ldr	x14, [x0, #CTX_HCRX_EL2]
-	msr	hcrx_el2, x14
-	ret
-endfunc el2_sysregs_context_restore_hcx
-#endif /* ENABLE_FEAT_HCX */
 #endif /* CTX_INCLUDE_EL2_REGS */
 
 /* ------------------------------------------------------------------
diff --git a/lib/el3_runtime/aarch64/context_mgmt.c b/lib/el3_runtime/aarch64/context_mgmt.c
index 46e191cc0..3bcefdb5d 100644
--- a/lib/el3_runtime/aarch64/context_mgmt.c
+++ b/lib/el3_runtime/aarch64/context_mgmt.c
@@ -320,9 +320,9 @@ static void setup_context_common(cpu_context_t *ctx, const entry_point_info_t *e
 	 * If FEAT_HCX is enabled, enable access to HCRX_EL2 by setting
 	 * SCR_EL3.HXEn.
 	 */
-#if ENABLE_FEAT_HCX
-	scr_el3 |= SCR_HXEn_BIT;
-#endif
+	if (is_feat_hcx_supported()) {
+		scr_el3 |= SCR_HXEn_BIT;
+	}
 
 	/*
 	 * If FEAT_RNG_TRAP is enabled, all reads of the RNDR and RNDRRS
@@ -873,9 +873,9 @@ void cm_el2_sysregs_context_save(uint32_t security_state)
 #if ENABLE_FEAT_CSV2_2
 		el2_sysregs_context_save_csv2(el2_sysregs_ctx);
 #endif
-#if ENABLE_FEAT_HCX
-		el2_sysregs_context_save_hcx(el2_sysregs_ctx);
-#endif
+		if (is_feat_hcx_supported()) {
+			write_ctx_reg(el2_sysregs_ctx, CTX_HCRX_EL2, read_hcrx_el2());
+		}
 	}
 }
 
@@ -931,9 +931,9 @@ void cm_el2_sysregs_context_restore(uint32_t security_state)
 #if ENABLE_FEAT_CSV2_2
 		el2_sysregs_context_restore_csv2(el2_sysregs_ctx);
 #endif
-#if ENABLE_FEAT_HCX
-		el2_sysregs_context_restore_hcx(el2_sysregs_ctx);
-#endif
+		if (is_feat_hcx_supported()) {
+			write_hcrx_el2(read_ctx_reg(el2_sysregs_ctx, CTX_HCRX_EL2));
+		}
 	}
 }
 #endif /* CTX_INCLUDE_EL2_REGS */