Re: [Xen-devel] [PATCH v1] x86/mm: Clean IOMMU flags from p2m-pt code

[Jan Beulich <JBeulich@xxxxxxxx>]

>>> On 18.06.19 at 13:54, <aisaila@xxxxxxxxxxxxxxx> wrote:
> At the moment the IOMMU flags are not used in p2m-pt and could be used
> on other application.

I don't understand the second half of this sentence. I guess anyway
that you want to at least mention the fact that CPU and IOMMU page
tables can't be shared anymore, ideally citing the commit that made
this impossible.

> This patch aims to clean the use of IOMMU flags on the AMD p2m side.
> 
> Signed-off-by: Alexandru Isaila <aisaila@xxxxxxxxxxxxxxx>
> Suggested-by: George Dunlap <george.dunlap@xxxxxxxxxx>

Nit: The natural order is the other way around, showing the flow
of events.

> @@ -36,13 +35,12 @@
>  #include <asm/p2m.h>
>  #include <asm/mem_sharing.h>
>  #include <asm/hvm/nestedhvm.h>
> -#include <asm/hvm/svm/amd-iommu-proto.h>
>  
>  #include "mm-locks.h"
>  
>  /*
>   * We may store INVALID_MFN in PTEs.  We need to clip this to avoid trampling
> - * over higher-order bits (NX, p2m type, IOMMU flags).  We seem to not need
> + * over higher-order bits (NX, p2m type).  We seem to not need
>   * to unclip on the read path, as callers are concerned only with p2m type in
>   * such cases.
>   */

Please re-flow the remainder of the comment.

> @@ -165,16 +163,6 @@ p2m_free_entry(struct p2m_domain *p2m, l1_pgentry_t 

Below the previous but ahead of this hunk there's p2m_type_to_flags(),
which has a comment that looks to want adjustment (removal?) as well.

Jan
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