Re: [PATCH for-4.15 v5 1/3] xen/iommu: x86: Don't try to free page tables is the IOMMU is not enabled

[Jan Beulich <jbeulich@xxxxxxxx>]

On 26.02.2021 11:56, Julien Grall wrote:
> From: Julien Grall <jgrall@xxxxxxxxxx>
> 
> When using CONFIG_BIGMEM=y, the page_list cannot be accessed whilst it
> is is unitialized. However, iommu_free_pgtables() will be called even if
> the domain is not using an IOMMU.
> 
> Consequently, Xen will try to go through the page list and deference a
> NULL pointer.
> 
> Bail out early if the domain is not using an IOMMU.
> 
> Fixes: 15bc9a1ef51c ("x86/iommu: add common page-table allocator")
> Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx>

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>