RE: [for-4.15][PATCH v2 2/5] xen/iommu: Check if the IOMMU was initialized before tearing down

[Paul Durrant <xadimgnik@xxxxxxxxx>]

> -----Original Message-----
> From: Julien Grall <julien@xxxxxxx>
> Sent: 09 February 2021 15:28
> To: xen-devel@xxxxxxxxxxxxxxxxxxxx
> Cc: hongyxia@xxxxxxxxxxxx; iwj@xxxxxxxxxxxxxx; Julien Grall 
> <jgrall@xxxxxxxxxx>; Jan Beulich
> <jbeulich@xxxxxxxx>; Paul Durrant <paul@xxxxxxx>
> Subject: [for-4.15][PATCH v2 2/5] xen/iommu: Check if the IOMMU was 
> initialized before tearing down
> 
> From: Julien Grall <jgrall@xxxxxxxxxx>
> 
> is_iommu_enabled() will return true even if the IOMMU has not been
> initialized (e.g. the ops are not set).
> 
> In the case of an early failure in arch_domain_init(), the function
> iommu_destroy_domain() will be called even if the IOMMU is not
> initialized.
> 
> This will result to dereference the ops which will be NULL and an host
> crash.
> 
> Fix the issue by checking that ops has been set before accessing it.
> 
> Fixes: 71e617a6b8f6 ("use is_iommu_enabled() where appropriate...")
> Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx>

Reviewed-by: Paul Durrant <paul@xxxxxxx>