Re: [PATCH 1/3] x86/pv: Options to disable and/or compile out 32bit PV support

2020-04-27 Thread Andrew Cooper
On 24/04/2020 06:28, Jürgen Groß wrote: > On 23.04.20 19:35, Andrew Cooper wrote: >> On 21/04/2020 07:02, Jan Beulich wrote: >>> On 20.04.2020 20:05, Andrew Cooper wrote: On 20/04/2020 15:05, Jan Beulich wrote: > I'm in particular > concerned that we may gain a large number of such

Re: [PATCH 1/3] x86/pv: Options to disable and/or compile out 32bit PV support

2020-04-24 Thread Jan Beulich
On 23.04.2020 19:35, Andrew Cooper wrote: > On 21/04/2020 07:02, Jan Beulich wrote: >> On 20.04.2020 20:05, Andrew Cooper wrote: >>> On 20/04/2020 15:05, Jan Beulich wrote: I'm in particular concerned that we may gain a large number of such printk()s over time, if we added them in

Re: [PATCH 1/3] x86/pv: Options to disable and/or compile out 32bit PV support

2020-04-23 Thread Andrew Cooper
On 21/04/2020 07:02, Jan Beulich wrote: > On 20.04.2020 20:05, Andrew Cooper wrote: >> On 20/04/2020 15:05, Jan Beulich wrote: >>> I'm in particular >>> concerned that we may gain a large number of such printk()s over >>> time, if we added them in such cases. >> The printk() was a bit of an

Re: [PATCH 1/3] x86/pv: Options to disable and/or compile out 32bit PV support

2020-04-21 Thread Jan Beulich
On 20.04.2020 20:05, Andrew Cooper wrote: > On 20/04/2020 15:05, Jan Beulich wrote: >> On 17.04.2020 17:50, Andrew Cooper wrote: >>> This is the start of some performance and security-hardening improvements, >>> based on the fact that 32bit PV guests are few and far between these days. >>> >>>

Re: [PATCH 1/3] x86/pv: Options to disable and/or compile out 32bit PV support

2020-04-20 Thread Andrew Cooper
On 20/04/2020 15:05, Jan Beulich wrote: > On 17.04.2020 17:50, Andrew Cooper wrote: >> This is the start of some performance and security-hardening improvements, >> based on the fact that 32bit PV guests are few and far between these days. >> >> Ring1 is full or architectural corner cases, such as

Re: [PATCH 1/3] x86/pv: Options to disable and/or compile out 32bit PV support

2020-04-20 Thread Andrew Cooper
On 20/04/2020 14:47, Roger Pau Monné wrote: > On Fri, Apr 17, 2020 at 04:50:02PM +0100, Andrew Cooper wrote: >> This is the start of some performance and security-hardening improvements, >> based on the fact that 32bit PV guests are few and far between these days. >> >> Ring1 is full or

Re: [PATCH 1/3] x86/pv: Options to disable and/or compile out 32bit PV support

2020-04-20 Thread Jan Beulich
On 17.04.2020 17:50, Andrew Cooper wrote: > --- a/xen/arch/x86/Kconfig > +++ b/xen/arch/x86/Kconfig > @@ -49,6 +49,22 @@ config PV > > If unsure, say Y. > > +config PV32 > + bool "Support for 32bit PV guests" > + depends on PV > + default y I guess I can see why you don't

Re: [PATCH 1/3] x86/pv: Options to disable and/or compile out 32bit PV support

2020-04-20 Thread Jan Beulich
On 17.04.2020 17:50, Andrew Cooper wrote: > This is the start of some performance and security-hardening improvements, > based on the fact that 32bit PV guests are few and far between these days. > > Ring1 is full or architectural corner cases, such as counting as supervisor ... full of ... >

Re: [PATCH 1/3] x86/pv: Options to disable and/or compile out 32bit PV support

2020-04-20 Thread Roger Pau Monné
On Fri, Apr 17, 2020 at 04:50:02PM +0100, Andrew Cooper wrote: > This is the start of some performance and security-hardening improvements, > based on the fact that 32bit PV guests are few and far between these days. > > Ring1 is full or architectural corner cases, such as counting as supervisor

[PATCH 1/3] x86/pv: Options to disable and/or compile out 32bit PV support

2020-04-17 Thread Andrew Cooper
This is the start of some performance and security-hardening improvements, based on the fact that 32bit PV guests are few and far between these days. Ring1 is full or architectural corner cases, such as counting as supervisor from a paging point of view. This accounts for a substantial