[boot-wrapper 7/7] aarch64: Start Xen on Armv8-R at EL2

[Luca Fancellu]

When bootwrapper is compiled with Xen support and it is started
at EL2 on Armv8-R AArch64, keep the current EL and jump to the
Xen image.

Additionally, don't permit the usage of hvc conduit when Xen
kernel is passed, because it's not supported.

Signed-off-by: Luca Fancellu <luca.fancellu at arm.com>
---
 Makefile.am         | 1 +
 arch/aarch64/boot.S | 7 +++++++
 configure.ac        | 3 +++
 3 files changed, 11 insertions(+)

diff --git a/Makefile.am b/Makefile.am
index 34fbfb1f4ff8..bafce34682c3 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -112,6 +112,7 @@ XEN_CHOSEN	:= xen,xen-bootargs = \"$(XEN_CMDLINE)\";		\
 			compatible = \"xen,linux-zimage\", \"xen,multiboot-module\"; \
 			reg = <0x0 $(DOM0_OFFSET) 0x0 $(KERNEL_SIZE)>;	\
 		   };
+DEFINES		+= -DXEN
 endif
 
 if INITRD
diff --git a/arch/aarch64/boot.S b/arch/aarch64/boot.S
index b2b9863b8d6a..0b30b82ad6d9 100644
--- a/arch/aarch64/boot.S
+++ b/arch/aarch64/boot.S
@@ -88,6 +88,7 @@ reset_at_el2:
 	cmp	x0, 0xf
 	bne	reset_no_el3
 
+#if !defined(XEN)
 	/*
 	 * Armv8-R AArch64 is found, check if Linux can be booted.
 	 * Check MSA_frac, bits [55:52]:
@@ -107,6 +108,12 @@ reset_at_el2:
 	mov	w0, #SPSR_KERNEL_EL1
 	ldr	x1, =spsr_to_elx
 	str	w0, [x1]
+#else
+	/* Start XEN on Armv8-R at EL2 */
+	mov	w0, #1
+	ldr	x1, =flag_keep_el
+	str	w0, [x1]
+#endif
 
 	cpuid	x0, x1
 	bl	find_logical_id
diff --git a/configure.ac b/configure.ac
index 44459a4c849e..a5175db4148a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -95,6 +95,9 @@ AM_CONDITIONAL([PSCI_HVC], [test "x$USE_PSCI" = "xhvc"])
 AS_IF([test "x$USE_PSCI" = "xno" -a "x$KERNEL_ES" = "x32"],
 	[AC_MSG_ERROR([With an AArch32 kernel, boot method must be PSCI.])]
 )
+AS_IF([test "x$USE_PSCI" = "xhvc" -a "x$X_IMAGE" != "x"],
+	[AC_MSG_ERROR([With Xen kernel, PSCI conduit must be smc.])]
+)
 AC_SUBST([PSCI_METHOD], [$USE_PSCI])
 
 # Allow a user to pass --with-initrd
-- 
2.34.1