Re: [PATCH v2 2/2] x86/pv: Rewrite segment context switching from scratch

2020-09-07 Thread Jan Beulich
On 04.09.2020 15:52, Andrew Cooper wrote: > There are multiple bugs with the existing implementation. > > On AMD CPUs prior to Zen2, loading a NUL segment selector doesn't clear the > segment base, which is a problem for 64bit code which typically expects to use > a NUL %fs/%gs selector. > > On a

[PATCH v2 2/2] x86/pv: Rewrite segment context switching from scratch

2020-09-04 Thread Andrew Cooper
There are multiple bugs with the existing implementation. On AMD CPUs prior to Zen2, loading a NUL segment selector doesn't clear the segment base, which is a problem for 64bit code which typically expects to use a NUL %fs/%gs selector. On a context switch from any PV vcpu, to a 64bit PV vcpu wit