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Re: [XEN PATCH] xen/arm: Relax GIC version check

(+ Ian)

Hi Vladimir,

On 20/01/2021 11:26, Vladimir Murzin wrote:
Supported values are

0b0000 GIC CPU interface system registers not implemented.

0b0001 System register interface to versions 3.0 and 4.0 of the GIC
        CPU interface is supported.

0b0011 System register interface to version 4.1 of the GIC CPU
        interface is supported.

4.1 is still backward compatible with 4.0/3.0, moreover ARM ARM
guarantees that future versions of the GIC CPU interface retain
backwards compatible.

Signed-off-by: Vladimir Murzin <vladimir.murzin@xxxxxxx>

Acked-by: Julien Grall <jgrall@xxxxxxxxxx>

@Ian: I would like your put as the RM for 4.15.

Technically, it could be consider as a new "feature" because Xen would fail to boot on such HW.

However, I think the change is small enough and doesn't introduce risk on existing supported HW.

Therefore, I would like to merge it for 4.15. @Ian does it sounds good to you?

  xen/include/asm-arm/cpufeature.h | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/include/asm-arm/cpufeature.h b/xen/include/asm-arm/cpufeature.h
index 13a2739a6..c6e5711b2 100644
--- a/xen/include/asm-arm/cpufeature.h
+++ b/xen/include/asm-arm/cpufeature.h
@@ -17,7 +17,7 @@
  #define cpu_has_el3_64    (boot_cpu_feature64(el3) >= 1)
  #define cpu_has_fp        (boot_cpu_feature64(fp) < 8)
  #define cpu_has_simd      (boot_cpu_feature64(simd) < 8)
-#define cpu_has_gicv3     (boot_cpu_feature64(gic) == 1)
+#define cpu_has_gicv3     (boot_cpu_feature64(gic) >= 1)
#define cpu_feature32(c, feat) ((c)->pfr32.feat)

Julien Grall



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