ARMv7 may not support Virtualization Extensions

ARMv7-A Virtualization extensions brings new instructions and resources
that were supported by later architectures. Reference ARM ARM Issue C.c
[DDI0406C_C].

ERET and extended MSR/MRS instructions, as specified in [DDI0406C_C] in
ID_PFR1 description of bits[15:12] (Virtualization Extensions):
 A value of 0b0001 implies implementation of the HVC, ERET, MRS
 (Banked register), and MSR (Banked register) instructions. The ID_ISARs
 do not identify whether these instructions are implemented.

UDIV/SDIV were introduced with the Virtualization extensions, even if
not strictly related to the virtualization extensions.

If ARMv7 based platform does not set ARM_CORTEX_Ax=yes, platform
shall define ARMV7_SUPPORTS_VIRTUALIZATION to enable virtualization
extension related resources.

Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>

common/aarch32/debug.S

@@ -71,7 +71,15 @@ endfunc report_exception
 assert_msg1:
 	.asciz "ASSERT: File "
 assert_msg2:
+#if ARM_ARCH_MAJOR == 7 && !defined(ARMV7_SUPPORTS_VIRTUALIZATION)
+	/******************************************************************
+	 * Virtualization comes with the UDIV/SDIV instructions. If missing
+	 * write file line number in hexadecimal format.
+	 ******************************************************************/
+	.asciz " Line 0x"
+#else
 	.asciz " Line "
+#endif
 
 /* ---------------------------------------------------------------------------
  * Assertion support in assembly.
@@ -113,6 +121,13 @@ func asm_assert
 	bne	1f
 	mov	r4, r6
 
+#if ARM_ARCH_MAJOR == 7 && !defined(ARMV7_SUPPORTS_VIRTUALIZATION)
+	/******************************************************************
+	 * Virtualization comes with the UDIV/SDIV instructions. If missing
+	 * write file line number in hexadecimal format.
+	 ******************************************************************/
+	bl	asm_print_hex
+#else
 	/* Print line number in decimal */
 	mov	r6, #10			/* Divide by 10 after every loop iteration */
 	ldr	r5, =MAX_DEC_DIVISOR
@@ -124,6 +139,7 @@ dec_print_loop:
 	udiv	r5, r5, r6			/* Reduce divisor */
 	cmp	r5, #0
 	bne	dec_print_loop
+#endif
 
 	bl	plat_crash_console_flush
 

include/common/aarch32/asm_macros.S

@@ -79,6 +79,16 @@
 	ldr r0, =(\_name + \_size)
 	.endm
 
+#if ARM_ARCH_MAJOR == 7 && !defined(ARMV7_SUPPORTS_VIRTUALIZATION)
+	/*
+	 * ARMv7 cores without Virtualization extension do not support the
+	 * eret instruction.
+	 */
+	.macro eret
+	movs	pc, lr
+	.endm
+#endif
+
 #if (ARM_ARCH_MAJOR == 7)
 	/* ARMv7 does not support stl instruction */
 	.macro stl _reg, _write_lock

include/lib/aarch32/smcc_macros.S

@@ -22,6 +22,44 @@
 	mov	r0, sp
 	add	r0, r0, #SMC_CTX_SP_USR
 
+#if ARM_ARCH_MAJOR == 7 && !defined(ARMV7_SUPPORTS_VIRTUALIZATION)
+	/* Must be in secure state to restore Monitor mode */
+	ldcopr	r4, SCR
+	bic	r2, r4, #SCR_NS_BIT
+	stcopr	r2, SCR
+	isb
+
+	cps	#MODE32_sys
+	stm	r0!, {sp, lr}
+
+	cps	#MODE32_irq
+	mrs	r2, spsr
+	stm	r0!, {r2, sp, lr}
+
+	cps	#MODE32_fiq
+	mrs	r2, spsr
+	stm	r0!, {r2, sp, lr}
+
+	cps	#MODE32_svc
+	mrs	r2, spsr
+	stm	r0!, {r2, sp, lr}
+
+	cps	#MODE32_abt
+	mrs	r2, spsr
+	stm	r0!, {r2, sp, lr}
+
+	cps	#MODE32_und
+	mrs	r2, spsr
+	stm	r0!, {r2, sp, lr}
+
+	/* lr_mon is already saved by caller */
+	cps	#MODE32_mon
+	mrs	r2, spsr
+	stm	r0!, {r2}
+
+	stcopr	r4, SCR
+	isb
+#else
 	/* Save the banked registers including the current SPSR and LR */
 	mrs	r4, sp_usr
 	mrs	r5, lr_usr
@@ -44,9 +82,10 @@
 	mrs	r11, lr_und
 	mrs	r12, spsr
 	stm	r0!, {r4-r12}
-
 	/* lr_mon is already saved by caller */
+
 	ldcopr	r4, SCR
+#endif
 	str	r4, [sp, #SMC_CTX_SCR]
 	ldcopr	r4, PMCR
 	str	r4, [sp, #SMC_CTX_PMCR]
@@ -82,6 +121,44 @@
 
 	/* Restore the banked registers including the current SPSR */
 	add	r1, r0, #SMC_CTX_SP_USR
+
+#if ARM_ARCH_MAJOR == 7 && !defined(ARMV7_SUPPORTS_VIRTUALIZATION)
+	/* Must be in secure state to restore Monitor mode */
+	ldcopr	r4, SCR
+	bic	r2, r4, #SCR_NS_BIT
+	stcopr	r2, SCR
+	isb
+
+	cps	#MODE32_sys
+	ldm	r1!, {sp, lr}
+
+	cps	#MODE32_irq
+	ldm	r1!, {r2, sp, lr}
+	msr	spsr_fsxc, r2
+
+	cps	#MODE32_fiq
+	ldm	r1!, {r2, sp, lr}
+	msr	spsr_fsxc, r2
+
+	cps	#MODE32_svc
+	ldm	r1!, {r2, sp, lr}
+	msr	spsr_fsxc, r2
+
+	cps	#MODE32_abt
+	ldm	r1!, {r2, sp, lr}
+	msr	spsr_fsxc, r2
+
+	cps	#MODE32_und
+	ldm	r1!, {r2, sp, lr}
+	msr	spsr_fsxc, r2
+
+	cps	#MODE32_mon
+	ldm	r1!, {r2}
+	msr	spsr_fsxc, r2
+
+	stcopr	r4, SCR
+	isb
+#else
 	ldm	r1!, {r4-r12}
 	msr	sp_usr, r4
 	msr	lr_usr, r5
@@ -109,6 +186,7 @@
 	 * f->[31:24] and c->[7:0] bits of SPSR.
 	 */
 	msr	spsr_fsxc, r12
+#endif
 
 	/* Restore the LR */
 	ldr	lr, [r0, #SMC_CTX_LR_MON]

make_helpers/armv7-a-cpus.mk

@@ -36,7 +36,11 @@ endif
 #
 # ARMV7_SUPPORTS_LARGE_PAGE_ADDRESSING
 # Defined if core supports the Large Page Addressing extension.
+#
+# ARMV7_SUPPORTS_VIRTUALIZATION
+# Defined if ARMv7 core supports the Virtualization extension.
 
 ifeq ($(filter yes,$(ARM_CORTEX_A7) $(ARM_CORTEX_A12) $(ARM_CORTEX_A15) $(ARM_CORTEX_A17)),yes)
 $(eval $(call add_define,ARMV7_SUPPORTS_LARGE_PAGE_ADDRESSING))
+$(eval $(call add_define,ARMV7_SUPPORTS_VIRTUALIZATION))
 endif