From: Grygorii Strashko <grygorii_strashko@epam.com> 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% [teddy.astie@vates.tech: Suggested to use static inline functions vs macro combinations] Suggested-by: Teddy Astie <teddy.astie@vates.tech> Signed-off-by: Grygorii Strashko <grygorii_strashko@epam.com> --- changes in v3: - add raw_use_hvm_access() wrapper changes in v2: - use static inline functions instead of macro combinations xen/arch/x86/Makefile | 2 +- xen/arch/x86/include/asm/guest_access.h | 78 ++++++++++++++++++------- 2 files changed, 59 insertions(+), 21 deletions(-) diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile index XXXXXXX..XXXXXXX 100644 --- a/xen/arch/x86/Makefile +++ b/xen/arch/x86/Makefile @@ -XXX,XX +XXX,XX @@ obj-y += time.o obj-y += traps-setup.o obj-y += traps.o obj-$(CONFIG_INTEL) += tsx.o -obj-y += usercopy.o +obj-$(CONFIG_PV) += usercopy.o obj-y += x86_emulate.o obj-$(CONFIG_TBOOT) += tboot.o obj-y += hpet.o diff --git a/xen/arch/x86/include/asm/guest_access.h b/xen/arch/x86/include/asm/guest_access.h index XXXXXXX..XXXXXXX 100644 --- a/xen/arch/x86/include/asm/guest_access.h +++ b/xen/arch/x86/include/asm/guest_access.h @@ -XXX,XX +XXX,XX @@ #include <asm/hvm/guest_access.h> /* Raw access functions: no type checking. */ -#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)) -#define raw_copy_from_guest(dst, src, len) \ - (is_hvm_vcpu(current) ? \ - copy_from_user_hvm((dst), (src), (len)) : \ - copy_from_guest_pv(dst, src, len)) -#define raw_clear_guest(dst, len) \ - (is_hvm_vcpu(current) ? \ - clear_user_hvm((dst), (len)) : \ - clear_guest_pv(dst, len)) -#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)) -#define __raw_copy_from_guest(dst, src, len) \ - (is_hvm_vcpu(current) ? \ - copy_from_user_hvm((dst), (src), (len)) : \ - __copy_from_guest_pv(dst, src, len)) +static inline bool raw_use_hvm_access(const struct vcpu *v) +{ + return IS_ENABLED(CONFIG_HVM) && (!IS_ENABLED(CONFIG_PV) || is_hvm_vcpu(v)); +} + +static inline unsigned int raw_copy_to_guest(void *dst, const void *src, + unsigned int len) +{ + if ( raw_use_hvm_access(current) ) + return copy_to_user_hvm(dst, src, len); + else if ( IS_ENABLED(CONFIG_PV) ) + return copy_to_guest_pv(dst, src, len); + else + return len; +} + +static inline unsigned int raw_copy_from_guest(void *dst, const void *src, + unsigned int len) +{ + if ( raw_use_hvm_access(current) ) + return copy_from_user_hvm(dst, src, len); + else if ( IS_ENABLED(CONFIG_PV) ) + return copy_from_guest_pv(dst, src, len); + else + return len; +} + +static inline unsigned int raw_clear_guest(void *dst, unsigned int len) +{ + if ( raw_use_hvm_access(current) ) + return clear_user_hvm(dst, len); + else if ( IS_ENABLED(CONFIG_PV) ) + return clear_guest_pv(dst, len); + else + return len; +} + +static inline unsigned int __raw_copy_to_guest(void *dst, const void *src, + unsigned int len) +{ + if ( raw_use_hvm_access(current) ) + return copy_to_user_hvm(dst, src, len); + else if ( IS_ENABLED(CONFIG_PV) ) + return __copy_to_guest_pv(dst, src, len); + else + return len; +} + +static inline unsigned int __raw_copy_from_guest(void *dst, const void *src, + unsigned int len) +{ + if ( raw_use_hvm_access(current) ) + return copy_from_user_hvm(dst, src, len); + else if ( IS_ENABLED(CONFIG_PV) ) + return __copy_from_guest_pv(dst, src, len); + else + return len; +} /* * Pre-validate a guest handle. -- 2.34.1 From: Grygorii Strashko <grygorii_strashko@epam.com> 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). The measured (bloat-o-meter) improvement for (PV=n and HVM=y) case is about -11K. [teddy.astie@vates.tech: Suggested to use static inline functions vs macro combinations] Suggested-by: Teddy Astie <teddy.astie@vates.tech> Signed-off-by: Grygorii Strashko <grygorii_strashko@epam.com> --- changes in v5: - rebase - drop moving usercopy.c as it is not needed since commit 7370966d1cb7 ("x86: move / split usercopy.c to / into arch-specific library") changes in v4: - move usercopy.c into arch/x86/pv/ - rework to always dynamically check for HVM vcpu(domain) by using is_hvm_vcpu() as requested by Jan Beulich changes in v3: - add raw_use_hvm_access() wrapper changes in v2: - use static inline functions instead of macro combinations xen/arch/x86/include/asm/guest_access.h | 78 ++++++++++++++++++------- 1 file changed, 58 insertions(+), 20 deletions(-) diff --git a/xen/arch/x86/include/asm/guest_access.h b/xen/arch/x86/include/asm/guest_access.h index XXXXXXX..XXXXXXX 100644 --- a/xen/arch/x86/include/asm/guest_access.h +++ b/xen/arch/x86/include/asm/guest_access.h @@ -XXX,XX +XXX,XX @@ #include <asm/hvm/guest_access.h> /* Raw access functions: no type checking. */ -#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)) -#define raw_copy_from_guest(dst, src, len) \ - (is_hvm_vcpu(current) ? \ - copy_from_user_hvm((dst), (src), (len)) : \ - copy_from_guest_pv(dst, src, len)) -#define raw_clear_guest(dst, len) \ - (is_hvm_vcpu(current) ? \ - clear_user_hvm((dst), (len)) : \ - clear_guest_pv(dst, len)) -#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)) -#define __raw_copy_from_guest(dst, src, len) \ - (is_hvm_vcpu(current) ? \ - copy_from_user_hvm((dst), (src), (len)) : \ - __copy_from_guest_pv(dst, src, len)) +static inline unsigned int raw_copy_to_guest(void *dst, const void *src, + unsigned int len) +{ + if ( is_hvm_vcpu(current) ) + return copy_to_user_hvm(dst, src, len); + + if ( !IS_ENABLED(CONFIG_PV) ) + return len; + + return copy_to_guest_pv(dst, src, len); +} + +static inline unsigned int raw_copy_from_guest(void *dst, const void *src, + unsigned int len) +{ + if ( is_hvm_vcpu(current) ) + return copy_from_user_hvm(dst, src, len); + + if ( !IS_ENABLED(CONFIG_PV) ) + return len; + + return copy_from_guest_pv(dst, src, len); +} + +static inline unsigned int raw_clear_guest(void *dst, unsigned int len) +{ + if ( is_hvm_vcpu(current) ) + return clear_user_hvm(dst, len); + + if ( !IS_ENABLED(CONFIG_PV) ) + return len; + + return clear_guest_pv(dst, len); +} + +static inline unsigned int __raw_copy_to_guest(void *dst, const void *src, + unsigned int len) +{ + if ( is_hvm_vcpu(current) ) + return copy_to_user_hvm(dst, src, len); + + if ( !IS_ENABLED(CONFIG_PV) ) + return len; + + return __copy_to_guest_pv(dst, src, len); +} + +static inline unsigned int __raw_copy_from_guest(void *dst, const void *src, + unsigned int len) +{ + if ( is_hvm_vcpu(current) ) + return copy_from_user_hvm(dst, src, len); + + if ( !IS_ENABLED(CONFIG_PV) ) + return len; + + return __copy_from_guest_pv(dst, src, len); +} /* * Pre-validate a guest handle. -- 2.34.1