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The first patch fixes Xen PV regression introduced by 32-bit rewrite. Unlike the earlier version it uses ALTERNATIVE instruction and avoids using xen_sysexit (and sysret32 in compat mode) pv ops, as suggested by Andy. As result of this patch irq_enable_sysexit and usergs_sysret32 pv ops are not used anymore by anyone and so can be removed. v2: * patch both TEST and JZ intructions with a single JMP * Add magic prefix to X86_FEATURE_XENPV comment to avoid having...

The first patch fixes Xen PV regression introduced by 32-bit rewrite. Unlike the earlier version it uses ALTERNATIVE instruction and avoids using xen_sysexit (and sysret32 in compat mode) pv ops, as suggested by Andy. As result of this patch irq_enable_sysexit and usergs_sysret32 pv ops are not used anymore by anyone and so can be removed. v2: * patch both TEST and JZ intructions with a single JMP * Add magic prefix to X86_FEATURE_XENPV comment to avoid having...

...t we don't need to fix >>> up the stack and instead follow entry_SYSENTER_32's IRET path directly >>> to xen_iret. >>> >>> We can do the same thing for compat mode even though stack does not need >>> to be fixed. This will allow us to drop usergs_sysret32 paravirt op (in >>> the subsequent patch) >> >> Looks generally quite nice. Minor comments below: >> >>> --- a/arch/x86/entry/entry_32.S >>> +++ b/arch/x86/entry/entry_32.S >>> @@ -308,7 +308,8 @@ sysenter_past_esp: >>> >>>...

...rote: > On Thu, Nov 19, 2015 at 1:55 PM, Boris Ostrovsky > <boris.ostrovsky at oracle.com> wrote: >> The first patch fixes Xen PV regression introduced by 32-bit rewrite. Unlike the >> earlier version it uses ALTERNATIVE instruction and avoids using xen_sysexit >> (and sysret32 in compat mode) pv ops, as suggested by Andy. >> >> As result of this patch irq_enable_sysexit and usergs_sysret32 pv ops are not >> used anymore by anyone and so can be removed. > This whole series is: > > Acked-by: Andy Lutomirski <luto at kernel.org> > > No...

...rote: > On Thu, Nov 19, 2015 at 1:55 PM, Boris Ostrovsky > <boris.ostrovsky at oracle.com> wrote: >> The first patch fixes Xen PV regression introduced by 32-bit rewrite. Unlike the >> earlier version it uses ALTERNATIVE instruction and avoids using xen_sysexit >> (and sysret32 in compat mode) pv ops, as suggested by Andy. >> >> As result of this patch irq_enable_sysexit and usergs_sysret32 pv ops are not >> used anymore by anyone and so can be removed. > This whole series is: > > Acked-by: Andy Lutomirski <luto at kernel.org> > > No...

...end up calling xen_iret from xen_sysexit we don't need to fix > up the stack and instead follow entry_SYSENTER_32's IRET path directly > to xen_iret. > > We can do the same thing for compat mode even though stack does not need > to be fixed. This will allow us to drop usergs_sysret32 paravirt op (in > the subsequent patch) Looks generally quite nice. Minor comments below: > --- a/arch/x86/entry/entry_32.S > +++ b/arch/x86/entry/entry_32.S > @@ -308,7 +308,8 @@ sysenter_past_esp: > > movl %esp, %eax > call do_fast_syscall_32 > -...

...end up calling xen_iret from xen_sysexit we don't need to fix > up the stack and instead follow entry_SYSENTER_32's IRET path directly > to xen_iret. > > We can do the same thing for compat mode even though stack does not need > to be fixed. This will allow us to drop usergs_sysret32 paravirt op (in > the subsequent patch) Looks generally quite nice. Minor comments below: > --- a/arch/x86/entry/entry_32.S > +++ b/arch/x86/entry/entry_32.S > @@ -308,7 +308,8 @@ sysenter_past_esp: > > movl %esp, %eax > call do_fast_syscall_32 > -...

The first patch fixes Xen PV regression introduced by 32-bit rewrite. Unlike the earlier version it uses ALTERNATIVE instruction and avoids using xen_sysexit (and sysret32 in compat mode) pv ops, as suggested by Andy. (I ended up patching TEST with XOR to avoid extra NOPs, even though I said yesterday it would be wrong. It's not wrong) As result of this patch irq_enable_sysexit and usergs_sysret32 pv ops are not used anymore by anyone and so can be removed. Bor...

The first patch fixes Xen PV regression introduced by 32-bit rewrite. Unlike the earlier version it uses ALTERNATIVE instruction and avoids using xen_sysexit (and sysret32 in compat mode) pv ops, as suggested by Andy. (I ended up patching TEST with XOR to avoid extra NOPs, even though I said yesterday it would be wrong. It's not wrong) As result of this patch irq_enable_sysexit and usergs_sysret32 pv ops are not used anymore by anyone and so can be removed. Bor...