| Message ID | 20200909095920.25495-3-andrew.cooper3@citrix.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | x86/pv: Minor perf improvements in segment handling | expand |
On 09.09.2020 11:59, Andrew Cooper wrote: > To match the read side which is already split out. A future change will want > to use them. > > No functional change. > > Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> Acked-by: Jan Beulich <jbeulich@suse.com> Of course ... > --- a/xen/include/asm-x86/msr.h > +++ b/xen/include/asm-x86/msr.h > @@ -156,6 +156,24 @@ static inline unsigned long __rdgsbase(void) > return base; > } > > +static inline void __wrfsbase(unsigned long base) > +{ > +#ifdef HAVE_AS_FSGSBASE > + asm volatile ( "wrfsbase %0" :: "r" (base) ); > +#else > + asm volatile ( ".byte 0xf3, 0x48, 0x0f, 0xae, 0xd0" :: "a" (base) ); > +#endif > +} > + > +static inline void __wrgsbase(unsigned long base) > +{ > +#ifdef HAVE_AS_FSGSBASE > + asm volatile ( "wrgsbase %0" :: "r" (base) ); > +#else > + asm volatile ( ".byte 0xf3, 0x48, 0x0f, 0xae, 0xd8" :: "a" (base) ); > +#endif > +} ... I'd have preferred if you had used just a single leading underscore, despite realizing this would introduce an inconsistency with the read sides. Jan
On 10/09/2020 15:47, Jan Beulich wrote: > On 09.09.2020 11:59, Andrew Cooper wrote: >> To match the read side which is already split out. A future change will want >> to use them. >> >> No functional change. >> >> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> > Acked-by: Jan Beulich <jbeulich@suse.com> > Of course ... > >> --- a/xen/include/asm-x86/msr.h >> +++ b/xen/include/asm-x86/msr.h >> @@ -156,6 +156,24 @@ static inline unsigned long __rdgsbase(void) >> return base; >> } >> >> +static inline void __wrfsbase(unsigned long base) >> +{ >> +#ifdef HAVE_AS_FSGSBASE >> + asm volatile ( "wrfsbase %0" :: "r" (base) ); >> +#else >> + asm volatile ( ".byte 0xf3, 0x48, 0x0f, 0xae, 0xd0" :: "a" (base) ); >> +#endif >> +} >> + >> +static inline void __wrgsbase(unsigned long base) >> +{ >> +#ifdef HAVE_AS_FSGSBASE >> + asm volatile ( "wrgsbase %0" :: "r" (base) ); >> +#else >> + asm volatile ( ".byte 0xf3, 0x48, 0x0f, 0xae, 0xd8" :: "a" (base) ); >> +#endif >> +} > ... I'd have preferred if you had used just a single leading > underscore, despite realizing this would introduce an inconsistency > with the read sides. You're welcome to change them if you wish. As always, I value consistency far far higher than arbitrary rules which don't impact us in practice. ~Andrew
diff --git a/xen/include/asm-x86/msr.h b/xen/include/asm-x86/msr.h index 5e141ac5a5..16f95e7344 100644 --- a/xen/include/asm-x86/msr.h +++ b/xen/include/asm-x86/msr.h @@ -156,6 +156,24 @@ static inline unsigned long __rdgsbase(void) return base; } +static inline void __wrfsbase(unsigned long base) +{ +#ifdef HAVE_AS_FSGSBASE + asm volatile ( "wrfsbase %0" :: "r" (base) ); +#else + asm volatile ( ".byte 0xf3, 0x48, 0x0f, 0xae, 0xd0" :: "a" (base) ); +#endif +} + +static inline void __wrgsbase(unsigned long base) +{ +#ifdef HAVE_AS_FSGSBASE + asm volatile ( "wrgsbase %0" :: "r" (base) ); +#else + asm volatile ( ".byte 0xf3, 0x48, 0x0f, 0xae, 0xd8" :: "a" (base) ); +#endif +} + static inline unsigned long read_fs_base(void) { unsigned long base; @@ -199,11 +217,7 @@ static inline unsigned long read_gs_shadow(void) static inline void write_fs_base(unsigned long base) { if ( read_cr4() & X86_CR4_FSGSBASE ) -#ifdef HAVE_AS_FSGSBASE - asm volatile ( "wrfsbase %0" :: "r" (base) ); -#else - asm volatile ( ".byte 0xf3, 0x48, 0x0f, 0xae, 0xd0" :: "a" (base) ); -#endif + __wrfsbase(base); else wrmsrl(MSR_FS_BASE, base); } @@ -211,11 +225,7 @@ static inline void write_fs_base(unsigned long base) static inline void write_gs_base(unsigned long base) { if ( read_cr4() & X86_CR4_FSGSBASE ) -#ifdef HAVE_AS_FSGSBASE - asm volatile ( "wrgsbase %0" :: "r" (base) ); -#else - asm volatile ( ".byte 0xf3, 0x48, 0x0f, 0xae, 0xd8" :: "a" (base) ); -#endif + __wrgsbase(base); else wrmsrl(MSR_GS_BASE, base); }
To match the read side which is already split out. A future change will want to use them. No functional change. Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> --- CC: Jan Beulich <JBeulich@suse.com> CC: Roger Pau Monné <roger.pau@citrix.com> CC: Wei Liu <wl@xen.org> --- xen/include/asm-x86/msr.h | 30 ++++++++++++++++++++---------- 1 file changed, 20 insertions(+), 10 deletions(-)