Re: [PATCH 4/4] x86/xen: drop USERGS_SYSRET64 paravirt call

2020-11-17 Thread Jürgen Groß
On 16.11.20 17:28, Andy Lutomirski wrote: On Mon, Nov 16, 2020 at 7:23 AM Juergen Gross wrote: USERGS_SYSRET64 is used to return from a syscall via sysret, but a Xen PV guest will nevertheless use the iret hypercall, as there is no sysret PV hypercall defined. So instead of testing all the pr

Re: [PATCH 4/4] x86/xen: drop USERGS_SYSRET64 paravirt call

2020-11-16 Thread Andy Lutomirski
On Mon, Nov 16, 2020 at 7:23 AM Juergen Gross wrote: > > USERGS_SYSRET64 is used to return from a syscall via sysret, but > a Xen PV guest will nevertheless use the iret hypercall, as there > is no sysret PV hypercall defined. > > So instead of testing all the prerequisites for doing a sysret and

Re: [PATCH 4/4] x86/xen: drop USERGS_SYSRET64 paravirt call

2020-11-16 Thread Andy Lutomirski
On Mon, Nov 16, 2020 at 7:23 AM Juergen Gross wrote: > > USERGS_SYSRET64 is used to return from a syscall via sysret, but > a Xen PV guest will nevertheless use the iret hypercall, as there > is no sysret PV hypercall defined. > > So instead of testing all the prerequisites for doing a sysret and

[PATCH 4/4] x86/xen: drop USERGS_SYSRET64 paravirt call

2020-11-16 Thread Juergen Gross
USERGS_SYSRET64 is used to return from a syscall via sysret, but a Xen PV guest will nevertheless use the iret hypercall, as there is no sysret PV hypercall defined. So instead of testing all the prerequisites for doing a sysret and then mangling the stack for Xen PV again for doing an iret just u