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Subject[PATCH v4 5/6] arm64/xen: introduce CONFIG_XEN on ARM64
Date
Introduce CONFIG_XEN on ARM64, compile arch/arm/xen under arch/arm64.
Add the ARMv8 specific hypercall wrappers to arch/arm/xen/hypercall.S.

Align few lines in hypercall.S since we are at it.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>

Changes in v2:
- remove depends on !GENERIC_ATOMIC64;
- compile enlighten.c and grant_table.c from arch/arm directly;
- fix the privcmd implementation: according to the aarch64 procedure
call ABI the first 7 parameters are passed on registers so we don't need
to push/pop anything.

Changes in v3:
- update comment to reflect the actual hypercall calling convention.

Changes in v4:
- build the entire arch/arm/xen directory under arch/arm64, ifdef
hypercall.S appropriately.
---
arch/arm/xen/hypercall.S | 98 ++++++++++++++++++++++++++++++----------------
arch/arm64/Kconfig | 10 +++++
arch/arm64/Makefile | 1 +
3 files changed, 75 insertions(+), 34 deletions(-)

diff --git a/arch/arm/xen/hypercall.S b/arch/arm/xen/hypercall.S
index 199cb2d..114b356 100644
--- a/arch/arm/xen/hypercall.S
+++ b/arch/arm/xen/hypercall.S
@@ -31,51 +31,93 @@
*/

/*
- * The Xen hypercall calling convention is very similar to the ARM
- * procedure calling convention: the first paramter is passed in r0, the
- * second in r1, the third in r2 and the fourth in r3. Considering that
- * Xen hypercalls have 5 arguments at most, the fifth paramter is passed
- * in r4, differently from the procedure calling convention of using the
- * stack for that case.
+ * The Xen hypercall calling convention is very similar to the ARM/ARM64
+ * procedure calling convention: the first paramter is passed in r0/x0,
+ * the second in r1/x1, the third in r2/x2 and the fourth in r3/x3.
+ * Considering that Xen hypercalls have 5 arguments at most, the fifth
+ * paramter is always passed in r4/x4, differently from the ARM
+ * procedure calling convention of using the stack for that case.
*
- * The hypercall number is passed in r12.
+ * The hypercall number is passed in r12/x16.
*
- * The return value is in r0.
+ * The return value is in r0/x0.
*
- * The hvc ISS is required to be 0xEA1, that is the Xen specific ARM
- * hypercall tag.
+ * The hvc ISS is required to be 0xEA1, that is the Xen specific
+ * ARM/ARM64 hypercall tag.
*/

#include <linux/linkage.h>
#include <asm/assembler.h>
-#include <asm/opcodes-virt.h>
#include <xen/interface/xen.h>


#define XEN_IMM 0xEA1

+
+#ifdef CONFIG_ARM
+
+#include <asm/opcodes-virt.h>
+
+ENTRY(privcmd_call)
+ stmdb sp!, {r4}
+ mov r12, r0
+ mov r0, r1
+ mov r1, r2
+ mov r2, r3
+ ldr r3, [sp, #8]
+ ldr r4, [sp, #4]
+ __HVC(XEN_IMM)
+ ldm sp!, {r4}
+ mov pc, lr
+ENDPROC(privcmd_call);
+
#define HYPERCALL_SIMPLE(hypercall) \
ENTRY(HYPERVISOR_##hypercall) \
mov r12, #__HYPERVISOR_##hypercall; \
- __HVC(XEN_IMM); \
- mov pc, lr; \
+ __HVC(XEN_IMM); \
+ mov pc, lr; \
+ENDPROC(HYPERVISOR_##hypercall)
+
+#define HYPERCALL5(hypercall) \
+ENTRY(HYPERVISOR_##hypercall) \
+ stmdb sp!, {r4} \
+ ldr r4, [sp, #4] \
+ mov r12, #__HYPERVISOR_##hypercall; \
+ __HVC(XEN_IMM); \
+ ldm sp!, {r4} \
+ mov pc, lr \
ENDPROC(HYPERVISOR_##hypercall)

+#else /* ARM64 specific code below */
+
+ENTRY(privcmd_call)
+ mov x16, x0
+ mov x0, x1
+ mov x1, x2
+ mov x2, x3
+ mov x3, x4
+ mov x4, x5
+ hvc XEN_IMM
+ ret
+ENDPROC(privcmd_call);
+
+#define HYPERCALL_SIMPLE(hypercall) \
+ENTRY(HYPERVISOR_##hypercall) \
+ mov x16, #__HYPERVISOR_##hypercall; \
+ hvc XEN_IMM; \
+ ret; \
+ENDPROC(HYPERVISOR_##hypercall)
+
+#define HYPERCALL5 HYPERCALL_SIMPLE
+#endif
+
+
#define HYPERCALL0 HYPERCALL_SIMPLE
#define HYPERCALL1 HYPERCALL_SIMPLE
#define HYPERCALL2 HYPERCALL_SIMPLE
#define HYPERCALL3 HYPERCALL_SIMPLE
#define HYPERCALL4 HYPERCALL_SIMPLE

-#define HYPERCALL5(hypercall) \
-ENTRY(HYPERVISOR_##hypercall) \
- stmdb sp!, {r4} \
- ldr r4, [sp, #4] \
- mov r12, #__HYPERVISOR_##hypercall; \
- __HVC(XEN_IMM); \
- ldm sp!, {r4} \
- mov pc, lr \
-ENDPROC(HYPERVISOR_##hypercall)

.text

@@ -89,15 +131,3 @@ HYPERCALL2(memory_op);
HYPERCALL2(physdev_op);
HYPERCALL3(vcpu_op);

-ENTRY(privcmd_call)
- stmdb sp!, {r4}
- mov r12, r0
- mov r0, r1
- mov r1, r2
- mov r2, r3
- ldr r3, [sp, #8]
- ldr r4, [sp, #4]
- __HVC(XEN_IMM)
- ldm sp!, {r4}
- mov pc, lr
-ENDPROC(privcmd_call);
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 56b3f6d..b5d6ada 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -182,6 +182,16 @@ config HW_PERF_EVENTS

source "mm/Kconfig"

+config XEN_DOM0
+ def_bool y
+ depends on XEN
+
+config XEN
+ bool "Xen guest support on ARM64 (EXPERIMENTAL)"
+ depends on ARM64 && OF
+ help
+ Say Y if you want to run Linux in a Virtual Machine on Xen on ARM64.
+
endmenu

menu "Boot options"
diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index c95c5cb..4b298aa 100644
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -37,6 +37,7 @@ TEXT_OFFSET := 0x00080000
export TEXT_OFFSET GZFLAGS

core-y += arch/arm64/kernel/ arch/arm64/mm/
+core-$(CONFIG_XEN) += arch/arm/xen/
libs-y := arch/arm64/lib/ $(libs-y)
libs-y += $(LIBGCC)

--
1.7.2.5


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