| Message ID | 20210305150638.2675513-22-npiggin@gmail.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | KVM: PPC: Book3S: C-ify the P9 entry/exit code | expand |
On 06/03/2021 02:06, 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. > > Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru> > --- > 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 ffde1917ab68..24b0680f0ad7 100644 > --- a/arch/powerpc/kvm/book3s_hv.c > +++ b/arch/powerpc/kvm/book3s_hv.c > @@ -3623,7 +3623,8 @@ 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); >
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 ffde1917ab68..24b0680f0ad7 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -3623,7 +3623,8 @@ 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);
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. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> --- arch/powerpc/include/asm/time.h | 2 ++ arch/powerpc/kvm/book3s_hv.c | 3 ++- 2 files changed, 4 insertions(+), 1 deletion(-)