| Message ID | 1490865209-18283-12-git-send-email-Wei.Chen@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Wei, On 30/03/17 10:13, Wei Chen wrote: > We have provided an option to administrator to determine how to > handle the SErrors. In order to skip the check of pending SError, > in conventional way, we have to read the option every time before > we try to check the pending SError. This will add overhead to check > the option at every trap. > > The ARM32 supports the alternative patching feature. We can use an > ALTERNATIVE to avoid checking option at every trap. We added a new > cpufeature named "SKIP_CHECK_PENDING_VSERROR". This feature will be > enabled when the option is not diverse. > > Signed-off-by: Wei Chen <Wei.Chen@arm.com> Reviewed-by: Julien Grall <julien.grall@arm.com> > --- Stefano, this is requiring the alternative patch (see [1]) which is still in review. Wei, a general rule is to mention the dependencies between series. So we don't apply by mistake in the wrong order. Cheers, [1] https://lists.xenproject.org/archives/html/xen-devel/2017-03/msg04132.html > xen/arch/arm/arm32/entry.S | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/xen/arch/arm/arm32/entry.S b/xen/arch/arm/arm32/entry.S > index 2187226..105cae8 100644 > --- a/xen/arch/arm/arm32/entry.S > +++ b/xen/arch/arm/arm32/entry.S > @@ -1,5 +1,6 @@ > #include <asm/asm_defns.h> > #include <asm/regs.h> > +#include <asm/alternative.h> > #include <public/xen.h> > > #define SAVE_ONE_BANKED(reg) mrs r11, reg; str r11, [sp, #UREGS_##reg] > @@ -44,6 +45,14 @@ save_guest_regs: > SAVE_BANKED(fiq) > SAVE_ONE_BANKED(R8_fiq); SAVE_ONE_BANKED(R9_fiq); SAVE_ONE_BANKED(R10_fiq) > SAVE_ONE_BANKED(R11_fiq); SAVE_ONE_BANKED(R12_fiq); > + > + /* > + * If the SKIP_CHECK_PENDING_VSERROR has been set in the cpu feature, > + * the checking of pending SErrors will be skipped. > + */ > + ALTERNATIVE("nop", > + "b skip_check", > + SKIP_CHECK_PENDING_VSERROR) > /* > * Start to check pending virtual abort in the gap of Guest -> HYP > * world switch. > @@ -99,6 +108,7 @@ abort_guest_exit_end: > */ > bne return_from_trap > > +skip_check: > mov pc, lr > > #define DEFINE_TRAP_ENTRY(trap) \ >
On Thu, 30 Mar 2017, Julien Grall wrote: > Hi Wei, > > On 30/03/17 10:13, Wei Chen wrote: > > We have provided an option to administrator to determine how to > > handle the SErrors. In order to skip the check of pending SError, > > in conventional way, we have to read the option every time before > > we try to check the pending SError. This will add overhead to check > > the option at every trap. > > > > The ARM32 supports the alternative patching feature. We can use an > > ALTERNATIVE to avoid checking option at every trap. We added a new > > cpufeature named "SKIP_CHECK_PENDING_VSERROR". This feature will be > > enabled when the option is not diverse. > > > > Signed-off-by: Wei Chen <Wei.Chen@arm.com> > > Reviewed-by: Julien Grall <julien.grall@arm.com> > > > --- > > Stefano, this is requiring the alternative patch (see [1]) which is still in > review. > > Wei, a general rule is to mention the dependencies between series. So we don't > apply by mistake in the wrong order. Right. Thanks Wei for sending both the other patch and this series together, that helps me avoiding mistakes. But please add a note about the dependencies, just in case I forget. > Cheers, > > [1] https://lists.xenproject.org/archives/html/xen-devel/2017-03/msg04132.html > > > xen/arch/arm/arm32/entry.S | 10 ++++++++++ > > 1 file changed, 10 insertions(+) > > > > diff --git a/xen/arch/arm/arm32/entry.S b/xen/arch/arm/arm32/entry.S > > index 2187226..105cae8 100644 > > --- a/xen/arch/arm/arm32/entry.S > > +++ b/xen/arch/arm/arm32/entry.S > > @@ -1,5 +1,6 @@ > > #include <asm/asm_defns.h> > > #include <asm/regs.h> > > +#include <asm/alternative.h> > > #include <public/xen.h> > > > > #define SAVE_ONE_BANKED(reg) mrs r11, reg; str r11, [sp, #UREGS_##reg] > > @@ -44,6 +45,14 @@ save_guest_regs: > > SAVE_BANKED(fiq) > > SAVE_ONE_BANKED(R8_fiq); SAVE_ONE_BANKED(R9_fiq); > > SAVE_ONE_BANKED(R10_fiq) > > SAVE_ONE_BANKED(R11_fiq); SAVE_ONE_BANKED(R12_fiq); > > + > > + /* > > + * If the SKIP_CHECK_PENDING_VSERROR has been set in the cpu > > feature, > > + * the checking of pending SErrors will be skipped. > > + */ > > + ALTERNATIVE("nop", > > + "b skip_check", > > + SKIP_CHECK_PENDING_VSERROR) > > /* > > * Start to check pending virtual abort in the gap of Guest -> HYP > > * world switch. > > @@ -99,6 +108,7 @@ abort_guest_exit_end: > > */ > > bne return_from_trap > > > > +skip_check: > > mov pc, lr > > > > #define DEFINE_TRAP_ENTRY(trap) \ > > > > -- > Julien Grall >
On 2017/3/31 5:29, Stefano Stabellini wrote: > On Thu, 30 Mar 2017, Julien Grall wrote: >> Hi Wei, >> >> On 30/03/17 10:13, Wei Chen wrote: >>> We have provided an option to administrator to determine how to >>> handle the SErrors. In order to skip the check of pending SError, >>> in conventional way, we have to read the option every time before >>> we try to check the pending SError. This will add overhead to check >>> the option at every trap. >>> >>> The ARM32 supports the alternative patching feature. We can use an >>> ALTERNATIVE to avoid checking option at every trap. We added a new >>> cpufeature named "SKIP_CHECK_PENDING_VSERROR". This feature will be >>> enabled when the option is not diverse. >>> >>> Signed-off-by: Wei Chen <Wei.Chen@arm.com> >> >> Reviewed-by: Julien Grall <julien.grall@arm.com> >> >>> --- >> >> Stefano, this is requiring the alternative patch (see [1]) which is still in >> review. >> >> Wei, a general rule is to mention the dependencies between series. So we don't >> apply by mistake in the wrong order. > > Right. Thanks Wei for sending both the other patch and this series > together, that helps me avoiding mistakes. > > But please add a note about the dependencies, just in case I forget. > Stefano and Julien, thank you. I would place a note about the dependencies in next version. > >> Cheers, >> >> [1] https://lists.xenproject.org/archives/html/xen-devel/2017-03/msg04132.html >> >>> xen/arch/arm/arm32/entry.S | 10 ++++++++++ >>> 1 file changed, 10 insertions(+) >>> >>> diff --git a/xen/arch/arm/arm32/entry.S b/xen/arch/arm/arm32/entry.S >>> index 2187226..105cae8 100644 >>> --- a/xen/arch/arm/arm32/entry.S >>> +++ b/xen/arch/arm/arm32/entry.S >>> @@ -1,5 +1,6 @@ >>> #include <asm/asm_defns.h> >>> #include <asm/regs.h> >>> +#include <asm/alternative.h> >>> #include <public/xen.h> >>> >>> #define SAVE_ONE_BANKED(reg) mrs r11, reg; str r11, [sp, #UREGS_##reg] >>> @@ -44,6 +45,14 @@ save_guest_regs: >>> SAVE_BANKED(fiq) >>> SAVE_ONE_BANKED(R8_fiq); SAVE_ONE_BANKED(R9_fiq); >>> SAVE_ONE_BANKED(R10_fiq) >>> SAVE_ONE_BANKED(R11_fiq); SAVE_ONE_BANKED(R12_fiq); >>> + >>> + /* >>> + * If the SKIP_CHECK_PENDING_VSERROR has been set in the cpu >>> feature, >>> + * the checking of pending SErrors will be skipped. >>> + */ >>> + ALTERNATIVE("nop", >>> + "b skip_check", >>> + SKIP_CHECK_PENDING_VSERROR) >>> /* >>> * Start to check pending virtual abort in the gap of Guest -> HYP >>> * world switch. >>> @@ -99,6 +108,7 @@ abort_guest_exit_end: >>> */ >>> bne return_from_trap >>> >>> +skip_check: >>> mov pc, lr >>> >>> #define DEFINE_TRAP_ENTRY(trap) \ >>> >> >> -- >> Julien Grall >> >
diff --git a/xen/arch/arm/arm32/entry.S b/xen/arch/arm/arm32/entry.S index 2187226..105cae8 100644 --- a/xen/arch/arm/arm32/entry.S +++ b/xen/arch/arm/arm32/entry.S @@ -1,5 +1,6 @@ #include <asm/asm_defns.h> #include <asm/regs.h> +#include <asm/alternative.h> #include <public/xen.h> #define SAVE_ONE_BANKED(reg) mrs r11, reg; str r11, [sp, #UREGS_##reg] @@ -44,6 +45,14 @@ save_guest_regs: SAVE_BANKED(fiq) SAVE_ONE_BANKED(R8_fiq); SAVE_ONE_BANKED(R9_fiq); SAVE_ONE_BANKED(R10_fiq) SAVE_ONE_BANKED(R11_fiq); SAVE_ONE_BANKED(R12_fiq); + + /* + * If the SKIP_CHECK_PENDING_VSERROR has been set in the cpu feature, + * the checking of pending SErrors will be skipped. + */ + ALTERNATIVE("nop", + "b skip_check", + SKIP_CHECK_PENDING_VSERROR) /* * Start to check pending virtual abort in the gap of Guest -> HYP * world switch. @@ -99,6 +108,7 @@ abort_guest_exit_end: */ bne return_from_trap +skip_check: mov pc, lr #define DEFINE_TRAP_ENTRY(trap) \
We have provided an option to administrator to determine how to handle the SErrors. In order to skip the check of pending SError, in conventional way, we have to read the option every time before we try to check the pending SError. This will add overhead to check the option at every trap. The ARM32 supports the alternative patching feature. We can use an ALTERNATIVE to avoid checking option at every trap. We added a new cpufeature named "SKIP_CHECK_PENDING_VSERROR". This feature will be enabled when the option is not diverse. Signed-off-by: Wei Chen <Wei.Chen@arm.com> --- xen/arch/arm/arm32/entry.S | 10 ++++++++++ 1 file changed, 10 insertions(+)