[boot-wrapper v5] aarch64: Start Xen on Armv8-R at EL2

[Luca Fancellu <luca.fancellu@arm.com>]

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 using the SPSR_KERNEL as spsr_el2 value.

The only available boot method on Armv8-R AArch64 when starting
Xen is spin table at the moment, reflect this in the build
configuration.

Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
---
v5 changes:
 - Don't allow AArch64-r + Xen + PSCI from the build system, update the commit
   message.
v4 changes:
 - no changes
---
 Makefile.am         | 1 +
 arch/aarch64/boot.S | 2 +-
 configure.ac        | 5 +++++
 3 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/Makefile.am b/Makefile.am
index aecda694fd6c..a8d5c1b96822 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -127,6 +127,7 @@ 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 565397823cb4..3fcc63bf2437 100644
--- a/arch/aarch64/boot.S
+++ b/arch/aarch64/boot.S
@@ -100,7 +100,7 @@ ASM_FUNC(jump_kernel)
 	mov	x1, x21
 	mov	x2, x22
 	mov	x3, x23
-#if defined(BOOTWRAPPER_64R)
+#if defined(BOOTWRAPPER_64R) && !defined(XEN)
 	// On Armv8-R Linux needs to be booted at EL1
 	mov	x4, #SPSR_KERNEL_EL1
 #else
diff --git a/configure.ac b/configure.ac
index a433c89bd2ae..a16bc25508f3 100644
--- a/configure.ac
+++ b/configure.ac
@@ -115,6 +115,11 @@ AS_IF([test "x$USE_PSCI" != "xyes" -a "x$KERNEL_ES" = "x32"],
 	[AC_MSG_ERROR([With an AArch32 kernel, boot method must be PSCI.])]
 )
 
+# Don't allow PSCI + Xen + aarch64-r
+AS_IF([test "x$USE_PSCI" = "xyes" -a "x$USE_ARCH" = "xaarch64-r" -a "x$X_IMAGE" != "x"],
+	[AC_MSG_ERROR([With aarch64-r and Xen, PSCI must be disabled.])]
+)
+
 # Allow a user to pass --with-initrd
 AC_ARG_WITH([initrd],
 	AS_HELP_STRING([--with-initrd], [embed an initrd in the kernel image]),
-- 
2.34.1