On 06.11.2025 23:26, Grygorii Strashko wrote: > From: Grygorii Strashko <[email protected]> > > Xen uses below pattern for raw_x_guest() functions: > > define raw_copy_to_guest(dst, src, len) \ > (is_hvm_vcpu(current) ? \ > copy_to_user_hvm((dst), (src), (len)) : \ > copy_to_guest_pv(dst, src, len)) > > This pattern works depending on CONFIG_PV/CONFIG_HVM as: > - PV=y and HVM=y > Proper guest access function is selected depending on domain type. > - PV=y and HVM=n > Only PV domains are possible. is_hvm_domain/vcpu() will constify to "false" > and compiler will optimize code and skip HVM specific part. > - PV=n and HVM=y > Only HVM domains are possible. is_hvm_domain/vcpu() will not be constified. > No PV specific code will be optimized by compiler. > - PV=n and HVM=n > No guests should possible. The code will still follow PV path. > > Rework raw_x_guest() code to use static inline functions which account for > above PV/HVM possible configurations with main intention to optimize code > for (PV=n and HVM=y) case. > > For the case (PV=n and HVM=n) return "len" value indicating a failure (no > guests should be possible in this case, which means no access to guest > memory should ever happen). > > Finally build arch/x86/usercopy.c only for PV=y. > > The measured (bloat-o-meter) improvement for (PV=n and HVM=y) case is: > add/remove: 2/9 grow/shrink: 2/90 up/down: 1678/-32560 (-30882) > Total: Before=1937092, After=1906210, chg -1.59% > > Signed-off-by: Grygorii Strashko <[email protected]> > [[email protected]: Suggested to use static inline functions vs macro > combinations] > Suggested-by: Teddy Astie <[email protected]>
Just one formal request for now: Please send patches To: the list, with individuals on Cc: as necessary. Jan
