Re: [Xen-devel] [PATCH v1 1/2] x86/mm: Add mem access rights to NPT

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 30.05.18 at 13:20, <aisaila@xxxxxxxxxxxxxxx> wrote:
> On Mi, 2018-05-30 at 03:52 -0600, Jan Beulich wrote:
>> >
>> > >
>> > > >
>> > > > On 30.05.18 at 11:04, <aisaila@xxxxxxxxxxxxxxx> wrote:
>> > Sorry for the misunderstanding, I wanted to clarify if the 59:56
>> > bits
>> > are fully ok to be used or if not then where should I use 4 bits to
>> > store the mem access info?
>> I thought I had sufficiently explained this - you have two options:
>> 1) Make sure (via some prereq patch(es)) bit 59 has no other use, and
>>    then use 59:56.
>> 2) Use another range that's provably having no other use, e.g.
>>    58:55.
> I've checked and bits 40:52 are defined in asm/page.h for page flags.

40:52? Hardly.

> I've tried bits 53:56 and there where some problems with the guest not
> starting or the image freezing,

Well, you'll have to explain this (perhaps just to yourself).

> bits 62 and 63 are not free so 59:56 is
> the only space to be used for this purpose and is seems to function
> correctly.

Well - as said before, bit 59 is not available for use without some
prereq work.

Jan



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel