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Re: [Xen-devel] [PATCH] arm/gic-v3: Fix driver probe fail on GICv4 hardware

On 27/05/16 14:48, Shanker Donthineni wrote:
Hi Julien,

Hello Shanker,

On 05/27/2016 07:35 AM, Julien Grall wrote:
On 27/05/16 00:59, Shanker Donthineni wrote:
The current driver probe fails on hardware which has GICv4 version,
even though it is fully compatible to GICv3. This patch fixes the
issue by registering the same probe function for GICv4 hardware.

Signed-off-by: Shanker Donthineni <shankerd@xxxxxxxxxxxxxx>
   xen/arch/arm/gic-v3.c     | 13 +++++++++++++
   xen/include/asm-arm/gic.h |  1 +
   2 files changed, 14 insertions(+)

diff --git a/xen/arch/arm/gic-v3.c b/xen/arch/arm/gic-v3.c
index a095064..594cf6e 100644
--- a/xen/arch/arm/gic-v3.c
+++ b/xen/arch/arm/gic-v3.c
@@ -1604,10 +1604,23 @@ static int __init gicv3_acpi_preinit(const void *data)
       return 0;

+static int __init gicv4_acpi_preinit(const void *data)
+    gicv3_info.hw_version = GIC_V4;

It will crash Xen as soon as DOM0 is created (see the BUG() in 
arch_domain_create). Please test any patch before sending on the ML.

Anyway, there is no support of GICv4 in Xen. Instead Xen will drive it using 
the GICv3 driver. So the hardware version should be GIC_V3 here.

Yes, I know I am going to fix in a separate to fix dom0 boot issue some thing 
like below.

This should have been in the same patch or before. There is no point to have a patch adding support for GICv4 with ACPI which will lead to an obscure crash (a BUG() rather than a panic with a nice message).

  diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index 1365b4a..56a47f5 100644
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -571,6 +571,11 @@ int arch_domain_create(struct domain *d, unsigned int 
              d->arch.vgic.version = GIC_V3;

+        case GIC_V4:
+            config->gic_version = XEN_DOMCTL_CONFIG_GIC_V3;
+            d->arch.vgic.version = GIC_V3;
+            break;

As mentioned in my previous mail, there is no support of GICv4 in Xen. Although the GICv3 driver is supporting this hardware.So we should not advertise GIC_V4 outside of the driver until Xen will get enough knowledge of GICv4 which will require sensible change in the generic code.


Julien Grall

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