[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 8/9] xen/arm: traps: Avoid unnecessary VA -> IPA translation in abort handlers
On Wed, 22 Jun 2016, Julien Grall wrote: > Translating a VA to a IPA is expensive. Currently, Xen is assuming that > HPFAR_EL2 is only valid when the stage-2 data/instruction abort happened > during a translation table walk of a first stage translation (i.e S1PTW > is set). > > However, based on the ARM ARM (D7.2.34 in DDI 0487A.j), the register is > also valid when the data/instruction abort occured for a translation > fault. > > With this change, the VA -> IPA translation will only happen for > permission faults that are not related to a translation table of a > first stage translation. > > Signed-off-by: Julien Grall <julien.grall@xxxxxxx> > > xen/arch/arm/traps.c | 22 +++++++++++++++++++--- > 1 file changed, 19 insertions(+), 3 deletions(-) > > diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c > index 591de3c..0edc2cc 100644 > --- a/xen/arch/arm/traps.c > +++ b/xen/arch/arm/traps.c > @@ -2383,13 +2383,28 @@ static inline paddr_t get_faulting_ipa(vaddr_t gva) > return ipa; > } > > +static inline bool hpfar_is_valid(bool s1ptw, uint8_t fsc) > +{ > + /* > + * HPFAR is valid if one of the following cases are true: > + * 1. the stage 2 fault happen during a stage 1 page table walk > + * (the bit ESR_EL2.S1PTW is set) > + * 2. the fault was due to a translation fault > + * > + * Note that technically HPFAR is valid for other cases, but they > + * are currently not supported by Xen. > + */ > + return s1ptw || (fsc == FSC_FLT_TRANS); > +} > + > static void do_trap_instr_abort_guest(struct cpu_user_regs *regs, > const union hsr hsr) > { > int rc; > register_t gva = READ_SYSREG(FAR_EL2); > + uint8_t fsc = hsr.iabt.ifsc & ~FSC_LL_MASK; > > - switch ( hsr.iabt.ifsc & ~FSC_LL_MASK ) > + switch ( fsc ) > { > case FSC_FLT_PERM: > { > @@ -2400,7 +2415,7 @@ static void do_trap_instr_abort_guest(struct > cpu_user_regs *regs, > .kind = hsr.iabt.s1ptw ? npfec_kind_in_gpt : npfec_kind_with_gla > }; > > - if ( hsr.iabt.s1ptw ) > + if ( hpfar_is_valid(hsr.iabt.s1ptw, fsc) ) > gpa = get_faulting_ipa(gva); > else > { > @@ -2435,6 +2450,7 @@ static void do_trap_data_abort_guest(struct > cpu_user_regs *regs, > const struct hsr_dabt dabt = hsr.dabt; > int rc; > mmio_info_t info; > + uint8_t fsc = hsr.dabt.dfsc & ~FSC_LL_MASK; You should be able to modify the switch in this case too, right? > info.dabt = dabt; > #ifdef CONFIG_ARM_32 > @@ -2443,7 +2459,7 @@ static void do_trap_data_abort_guest(struct > cpu_user_regs *regs, > info.gva = READ_SYSREG64(FAR_EL2); > #endif > > - if ( dabt.s1ptw ) > + if ( hpfar_is_valid(hsr.iabt.s1ptw, fsc) ) > info.gpa = get_faulting_ipa(info.gva); > else > { > -- > 1.9.1 > _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
|
Lists.xenproject.org is hosted with RackSpace, monitoring our |