Re: [Xen-devel] [PATCH v2 1/7] x86: slightly reduce Meltdown band-aid overhead

2018-03-02 Thread Andrew Cooper
On 02/03/18 11:34, Jan Beulich wrote: On 01.03.18 at 20:21, wrote: >> On 08/02/18 09:20, Jan Beulich wrote: >> On 07.02.18 at 20:35, wrote: On 07/02/18 16:12, Jan Beulich wrote: > I'm not sure why I didn't do this right

Re: [Xen-devel] [PATCH v2 1/7] x86: slightly reduce Meltdown band-aid overhead

2018-03-02 Thread Jan Beulich
>>> On 01.03.18 at 20:21, wrote: > On 08/02/18 09:20, Jan Beulich wrote: > On 07.02.18 at 20:35, wrote: >>> On 07/02/18 16:12, Jan Beulich wrote: I'm not sure why I didn't do this right away: By avoiding the use of global PTEs

Re: [Xen-devel] [PATCH v2 1/7] x86: slightly reduce Meltdown band-aid overhead

2018-03-01 Thread Andrew Cooper
On 08/02/18 09:20, Jan Beulich wrote: On 07.02.18 at 20:35, wrote: >> On 07/02/18 16:12, Jan Beulich wrote: >>> I'm not sure why I didn't do this right away: By avoiding the use of >>> global PTEs in the cloned directmap, there's no need to fiddle with >>> CR4.PGE

Re: [Xen-devel] [PATCH v2 1/7] x86: slightly reduce Meltdown band-aid overhead

2018-02-08 Thread Jan Beulich
>>> On 07.02.18 at 20:35, wrote: > On 07/02/18 16:12, Jan Beulich wrote: >> I'm not sure why I didn't do this right away: By avoiding the use of >> global PTEs in the cloned directmap, there's no need to fiddle with >> CR4.PGE on any of the entry paths. Only the exit

Re: [Xen-devel] [PATCH v2 1/7] x86: slightly reduce Meltdown band-aid overhead

2018-02-07 Thread Andrew Cooper
On 07/02/18 16:12, Jan Beulich wrote: > I'm not sure why I didn't do this right away: By avoiding the use of > global PTEs in the cloned directmap, there's no need to fiddle with > CR4.PGE on any of the entry paths. Only the exit paths need to flush > global mappings. > > The reduced flushing,