Re: [Xen-devel] [PATCH V8 2/5] x86/hvm: pkeys, add pkeys support for guest_walk_tables

["Han, Huaitong" <huaitong.han@xxxxxxxxx>]

On Wed, 2016-02-03 at 02:43 -0700, Jan Beulich wrote:
> > > > On 02.02.16 at 08:35, <huaitong.han@xxxxxxxxx> wrote:
> > Protection keys define a new 4-bit protection key field(PKEY) in
> > bits 62:59 
> > of
> > leaf entries of the page tables.
> > 
> > PKRU register defines 32 bits, there are 16 domains and 2 attribute
> > bits per
> > domain in pkru, for each i (0 â i â 15), PKRU[2i] is the access
> > -disable bit 
> > for
> > protection key i (ADi); PKRU[2i+1] is the write-disable bit for
> > protection 
> > key
> > i (WDi). PKEY is index to a defined domain.
> > 
> > A fault is considered as a PKU violation if all of the following
> > conditions 
> > are
> > true:
> > 1.CR4_PKE=1.
> > 2.EFER_LMA=1.
> > 3.Page is present with no reserved bit violations.
> > 4.The access is not an instruction fetch.
> > 5.The access is to a user page.
> > 6.PKRU.AD=1
> >     or The access is a data write and PKRU.WD=1
> >                 and either CR0.WP=1 or it is a user access.
> > 
> > Signed-off-by: Huaitong Han <huaitong.han@xxxxxxxxx>
> 
> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
> albeit ...
> 
> > Changes in v8:
> > *Abstract out _write_cr4.
> 
> ... I'm not happy about the chose name and will try to remember
> to change it to e.g. raw_write_cr4(). Names starting with an
> underscore and a lower case letter are reserved to symbols
> local to a given translation unit, which in my reading doesn't fit
> with them getting placed in header files.
It will be updated in V9.
> 
> Jan
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