| Message ID | 20210323010305.1045293-25-npiggin@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | KVM: PPC: Book3S: C-ify the P9 entry/exit code | expand |
On 23/03/2021 12:02, Nicholas Piggin wrote: > On processors that don't suppress the HDEC exceptions when LPCR[HDICE]=0, > this could help reduce needless guest exits due to leftover exceptions on > entering the guest. > > Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru> > Signed-off-by: Nicholas Piggin <npiggin@gmail.com> ERROR: modpost: "decrementer_max" [arch/powerpc/kvm/kvm-hv.ko] undefined! need this: --- a/arch/powerpc/kernel/time.c +++ b/arch/powerpc/kernel/time.c @@ -89,6 +89,7 @@ static struct clocksource clocksource_timebase = { #define DECREMENTER_DEFAULT_MAX 0x7FFFFFFF u64 decrementer_max = DECREMENTER_DEFAULT_MAX; +EXPORT_SYMBOL_GPL(decrementer_max); > --- > arch/powerpc/include/asm/time.h | 2 ++ > arch/powerpc/kvm/book3s_hv.c | 3 ++- > 2 files changed, 4 insertions(+), 1 deletion(-) > > diff --git a/arch/powerpc/include/asm/time.h b/arch/powerpc/include/asm/time.h > index 8dd3cdb25338..68d94711811e 100644 > --- a/arch/powerpc/include/asm/time.h > +++ b/arch/powerpc/include/asm/time.h > @@ -18,6 +18,8 @@ > #include <asm/vdso/timebase.h> > > /* time.c */ > +extern u64 decrementer_max; > + > extern unsigned long tb_ticks_per_jiffy; > extern unsigned long tb_ticks_per_usec; > extern unsigned long tb_ticks_per_sec; > diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c > index 8215430e6d5e..bb30c5ab53d1 100644 > --- a/arch/powerpc/kvm/book3s_hv.c > +++ b/arch/powerpc/kvm/book3s_hv.c > @@ -3658,7 +3658,8 @@ static int kvmhv_load_hv_regs_and_go(struct kvm_vcpu *vcpu, u64 time_limit, > vc->tb_offset_applied = 0; > } > > - mtspr(SPRN_HDEC, 0x7fffffff); > + /* HDEC must be at least as large as DEC, so decrementer_max fits */ > + mtspr(SPRN_HDEC, decrementer_max); > > switch_mmu_to_host_radix(kvm, host_pidr); > >
Excerpts from Alexey Kardashevskiy's message of March 26, 2021 12:05 pm: > > > On 23/03/2021 12:02, Nicholas Piggin wrote: >> On processors that don't suppress the HDEC exceptions when LPCR[HDICE]=0, >> this could help reduce needless guest exits due to leftover exceptions on >> entering the guest. >> >> Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru> >> Signed-off-by: Nicholas Piggin <npiggin@gmail.com> > > > ERROR: modpost: "decrementer_max" [arch/powerpc/kvm/kvm-hv.ko] undefined! > > > need this: > > --- a/arch/powerpc/kernel/time.c > +++ b/arch/powerpc/kernel/time.c > @@ -89,6 +89,7 @@ static struct clocksource clocksource_timebase = { > > #define DECREMENTER_DEFAULT_MAX 0x7FFFFFFF > u64 decrementer_max = DECREMENTER_DEFAULT_MAX; > +EXPORT_SYMBOL_GPL(decrementer_max); Added. Thanks, Nick
diff --git a/arch/powerpc/include/asm/time.h b/arch/powerpc/include/asm/time.h index 8dd3cdb25338..68d94711811e 100644 --- a/arch/powerpc/include/asm/time.h +++ b/arch/powerpc/include/asm/time.h @@ -18,6 +18,8 @@ #include <asm/vdso/timebase.h> /* time.c */ +extern u64 decrementer_max; + extern unsigned long tb_ticks_per_jiffy; extern unsigned long tb_ticks_per_usec; extern unsigned long tb_ticks_per_sec; diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 8215430e6d5e..bb30c5ab53d1 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -3658,7 +3658,8 @@ static int kvmhv_load_hv_regs_and_go(struct kvm_vcpu *vcpu, u64 time_limit, vc->tb_offset_applied = 0; } - mtspr(SPRN_HDEC, 0x7fffffff); + /* HDEC must be at least as large as DEC, so decrementer_max fits */ + mtspr(SPRN_HDEC, decrementer_max); switch_mmu_to_host_radix(kvm, host_pidr);