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Re: [Xen-devel] [PATCH v2 08/17] libxl/arm: Factor MPIDR computing codes out as a helper



Hi Shannon,

On 23/06/16 04:16, Shannon Zhao wrote:
From: Shannon Zhao <shannon.zhao@xxxxxxxxxx>

Factor MPIDR computing codes out as a helper, so it could be shared
between DT and ACPI.

Signed-off-by: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
---
  tools/libxl/libxl_arm.c      |  8 +-------
  tools/libxl/libxl_arm_acpi.h | 12 ++++++++++++
  2 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/tools/libxl/libxl_arm.c b/tools/libxl/libxl_arm.c
index f5db74b..a766732 100644
--- a/tools/libxl/libxl_arm.c
+++ b/tools/libxl/libxl_arm.c
@@ -312,13 +312,7 @@ static int make_cpus_node(libxl__gc *gc, void *fdt, int 
nr_cpus,
      for (i = 0; i < nr_cpus; i++) {
          const char *name;

-        /*
-         * According to ARM CPUs bindings, the reg field should match
-         * the MPIDR's affinity bits. We will use AFF0 and AFF1 when
-         * constructing the reg value of the guest at the moment, for it
-         * is enough for the current max vcpu number.
-         */
-        mpidr_aff = (i & 0x0f) | (((i >> 4) & 0xff) << 8);
+        mpidr_aff = libxl__compute_mpdir(i);
          name = GCSPRINTF("cpu@%"PRIx64, mpidr_aff);

          res = fdt_begin_node(fdt, name);
diff --git a/tools/libxl/libxl_arm_acpi.h b/tools/libxl/libxl_arm_acpi.h
index 5899210..9b58de6 100644
--- a/tools/libxl/libxl_arm_acpi.h
+++ b/tools/libxl/libxl_arm_acpi.h

I do not think libxl_arm_acpi.h is the right place to add libxl__compute_mpidr. This function is clearly not ACPI specific. You may want to rename this file libxl_arm.h instead.

@@ -23,6 +23,18 @@ int libxl__prepare_acpi(libxl__gc *gc, 
libxl_domain_build_info *info,
                          libxl__domain_build_state *state,
                          struct xc_dom_image *dom);

+static inline uint64_t libxl__compute_mpdir(int index)

'index' should be unsigned int. It would also make sense to name this variable 'cpuid'.

+{
+    /*
+     * According to ARM CPUs bindings, the reg field should match
+     * the MPIDR's affinity bits. We will use AFF0 and AFF1 when
+     * constructing the reg value of the guest at the moment, for it
+     * is enough for the current max vcpu number.
+     */
+    assert(index >= 0);

This will avoid this assert here.

+    return (index & 0x0f) | (((index >> 4) & 0xff) << 8);
+}
+
  /*
   * Local variables:
   * mode: C


Regards,

--
Julien Grall

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