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[Xen-devel] [PATCH v4 3/4] xen:arm: arm64: Add correct MPIDR_HWID_MASK value for ARM64

Currently, MPIDR_HWID_MASK is using the bit definition of AArch32
MPIDR register. But from D7.2.67 of ARM ARM (DDI 0487A.i) we can see
there are 4 levels of affinity on AArch64 whilst AArch32 has only 3.
So, this value is not correct when Xen is running on AArch64.

Now, we use the value 0xff00ffffff for this macro on AArch64. But
neither of this value and its bitwise invert value can be used in mov
instruction with the encoding of {imm16:shift} or {imms:immr}. So we
have to use ldr to load the bitwise invert value to register.

The details of mov immediate encoding are listed in C4.2.5 of ARM ARM
(DDI 0487A.i).

Signed-off-by: Wei Chen <Wei.Chen@xxxxxxxxxx>
1. Update version number.

1. Add version information of mentioned ARM ARM.

v1-->v2: Address Julien's comments
1. Fix typos in commit messages.
2. Explain valid MPIDR_HWID_MASK value in AArch64.
3. Simply explain mov immediate encoding.
 xen/arch/arm/arm64/head.S       | 2 +-
 xen/include/asm-arm/processor.h | 4 ++++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S
index d5831f2..3090beb 100644
--- a/xen/arch/arm/arm64/head.S
+++ b/xen/arch/arm/arm64/head.S
@@ -270,7 +270,7 @@ common_start:
         tbz   x0, _MPIDR_SMP, 1f     /* Multiprocessor extension not 
supported? */
         tbnz  x0, _MPIDR_UP, 1f      /* Uniprocessor system? */
-        mov   x13, #(~MPIDR_HWID_MASK)
+        ldr   x13, =(~MPIDR_HWID_MASK)
         bic   x24, x0, x13           /* Mask out flags to get CPU ID */
diff --git a/xen/include/asm-arm/processor.h b/xen/include/asm-arm/processor.h
index b4cce7e..284ad6a 100644
--- a/xen/include/asm-arm/processor.h
+++ b/xen/include/asm-arm/processor.h
@@ -18,7 +18,11 @@
 #define MPIDR_SMP           (_AC(1,U) << _MPIDR_SMP)
 #define MPIDR_AFF0_SHIFT    (0)
 #define MPIDR_AFF0_MASK     (_AC(0xff,U) << MPIDR_AFF0_SHIFT)
+#ifdef CONFIG_ARM_64
+#define MPIDR_HWID_MASK     _AC(0xff00ffffff,UL)
 #define MPIDR_HWID_MASK     _AC(0xffffff,U)
 #define MPIDR_LEVEL_BITS    (8)

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