Re: [PATCH 1/2] amd-iommu: use a bitfield for PTE/PDE

[Paul Durrant <Paul.Durrant@citrix.com>]

> -----Original Message-----
> From: Xen-devel [mailto:xen-devel-bounces@lists.xenproject.org] On Behalf
> Of Woods, Brian
> Sent: 13 February 2019 15:34
> To: Paul Durrant <Paul.Durrant@citrix.com>; xen-devel@lists.xenproject.org
> Cc: Andrew Cooper <Andrew.Cooper3@citrix.com>; Wei Liu
> <wei.liu2@citrix.com>; Jan Beulich <jbeulich@suse.com>; Suthikulpanit,
> Suravee <Suravee.Suthikulpanit@amd.com>; Roger Pau Monne
> <roger.pau@citrix.com>
> Subject: Re: [Xen-devel] [PATCH 1/2] amd-iommu: use a bitfield for PTE/PDE
> 
> On 2/13/19 3:45 AM, Paul Durrant wrote:
> >> -----Original Message-----
> >> From: Woods, Brian [mailto:Brian.Woods@amd.com]
> >> Sent: 12 February 2019 20:14
> >> To: Paul Durrant <Paul.Durrant@citrix.com>; xen-
> devel@lists.xenproject.org
> >> Cc: Suthikulpanit, Suravee <Suravee.Suthikulpanit@amd.com>; Jan Beulich
> >> <jbeulich@suse.com>; Andrew Cooper <Andrew.Cooper3@citrix.com>; Wei Liu
> >> <wei.liu2@citrix.com>; Roger Pau Monne <roger.pau@citrix.com>
> >> Subject: Re: [PATCH 1/2] amd-iommu: use a bitfield for PTE/PDE
> >>
> >> On 2/4/19 5:19 AM, Paul Durrant wrote:
> >>> The current use of get/set_field_from/in_reg_u32() is both inefficient
> >> and
> >>> requires some ugly casting.
> >>>
> >>> This patch defines a new bitfield structure (amd_iommu_pte) and uses
> >> this
> >>> structure in all PTE/PDE manipulation, resulting in much more readable
> >>> and compact code.
> >>>
> >>> NOTE: This commit also fixes one malformed comment in
> >>>         set_iommu_pte_present().
> >>>
> >>> Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
> >>
> >> Sorry about the delay.
> >>
> >> Nitpick here, but I'd rather have !!IOMMUF_{writable,readable} than
> >> true.
> >
> > That's pretty ugly. How about I pass an OR of the flags through to lower
> level functions rather than a pair of bools? If you're ok with that I'll
> send a v2.
> >
> >    Paul
> >
> 
> There's no need for a v2 based on that, that's just me nitpicking.
> There's no real nice way to do it without turning
> IOMMUF_{writable,readable} into bools or your suggested way which has
> more code to decode a flag.  Assuming everyone else is ok with the
> patches as are, it's fine.  If there's going to be a v2 for other
> reasons, I'll just leave it up to your discretion (other people may have
> stronger opinions about it anyway).
> 

Ok. Thanks Brian,

  Paul
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