> -----Original Message----- > From: Alexander Graf [mailto:agraf@xxxxxxx] > Sent: Wednesday, May 16, 2012 2:54 PM > To: Bhushan Bharat-R65777 > Cc: kvm-ppc@xxxxxxxxxxxxxxx > Subject: Re: [PATCH] KVM: PPC: booke: Added DECAR support > > On 05/16/2012 11:21 AM, Bhushan Bharat-R65777 wrote: > > > >> -----Original Message----- > >> From: Alexander Graf [mailto:agraf@xxxxxxx] > >> Sent: Wednesday, May 16, 2012 2:36 PM > >> To: Bhushan Bharat-R65777 > >> Cc: kvm-ppc@xxxxxxxxxxxxxxx > >> Subject: Re: [PATCH] KVM: PPC: booke: Added DECAR support > >> > >> On 05/16/2012 08:57 AM, Bhushan Bharat-R65777 wrote: > >>>> -----Original Message----- > >>>> From: Alexander Graf [mailto:agraf@xxxxxxx] > >>>> Sent: Tuesday, May 15, 2012 7:59 PM > >>>> To: Bhushan Bharat-R65777 > >>>> Cc: kvm-ppc@xxxxxxxxxxxxxxx; Bhushan Bharat-R65777 > >>>> Subject: Re: [PATCH] KVM: PPC: booke: Added DECAR support > >>>> > >>>> On 05/15/2012 09:33 AM, Bharat Bhushan wrote: > >>>>> Added the decrementer auto-reload support. > >>>>> > >>>>> Signed-off-by: Bharat Bhushan<bharat.bhushan@xxxxxxxxxxxxx> > >>>>> --- > >>>>> arch/powerpc/include/asm/kvm_host.h | 2 ++ > >>>>> arch/powerpc/kvm/booke.c | 5 +++++ > >>>>> arch/powerpc/kvm/booke_emulate.c | 7 ++++++- > >>>>> 3 files changed, 13 insertions(+), 1 deletions(-) > >>>>> > >>>>> diff --git a/arch/powerpc/include/asm/kvm_host.h > >>>>> b/arch/powerpc/include/asm/kvm_host.h > >>>>> index d848cdc..1d6f89e 100644 > >>>>> --- a/arch/powerpc/include/asm/kvm_host.h > >>>>> +++ b/arch/powerpc/include/asm/kvm_host.h > >>>>> @@ -414,7 +414,9 @@ struct kvm_vcpu_arch { > >>>>> ulong mcsrr1; > >>>>> ulong mcsr; > >>>>> u32 dec; > >>>>> +#ifdef CONFIG_BOOKE > >>>>> u32 decar; > >>>>> +#endif > >>>>> u32 tbl; > >>>>> u32 tbu; > >>>>> u32 tcr; > >>>>> diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c > >>>>> index 72f13f4..86681ee 100644 > >>>>> --- a/arch/powerpc/kvm/booke.c > >>>>> +++ b/arch/powerpc/kvm/booke.c > >>>>> @@ -1267,6 +1267,11 @@ void kvmppc_decrementer_func(unsigned long data) > >>>>> { > >>>>> struct kvm_vcpu *vcpu = (struct kvm_vcpu *)data; > >>>>> > >>>>> + if (vcpu->arch.tcr& TCR_ARE) { > >>>>> + vcpu->arch.dec = vcpu->arch.decar; > >>>>> + kvmppc_emulate_dec(vcpu); > >>>>> + } > >>>>> + > >>>>> kvmppc_set_tsr_bits(vcpu, TSR_DIS); > >>>>> } > >>>>> > >>>>> diff --git a/arch/powerpc/kvm/booke_emulate.c > >>>>> b/arch/powerpc/kvm/booke_emulate.c > >>>>> index 6c76397..83c3796 100644 > >>>>> --- a/arch/powerpc/kvm/booke_emulate.c > >>>>> +++ b/arch/powerpc/kvm/booke_emulate.c > >>>>> @@ -129,6 +129,9 @@ int kvmppc_booke_emulate_mtspr(struct kvm_vcpu > >>>>> *vcpu, int > >>>> sprn, ulong spr_val) > >>>>> kvmppc_set_tcr(vcpu, spr_val); > >>>>> break; > >>>>> > >>>>> + case SPRN_DECAR: > >>>>> + vcpu->arch.decar = spr_val; > >>>>> + break; > >>>>> /* > >>>>> * Note: SPRG4-7 are user-readable. > >>>>> * These values are loaded into the real SPRGs when resuming > >>>>> the @@ > >>>>> -244,7 +247,9 @@ int kvmppc_booke_emulate_mfspr(struct kvm_vcpu > >>>>> *vcpu, int > >>>> sprn, ulong *spr_val) > >>>>> case SPRN_TCR: > >>>>> *spr_val = vcpu->arch.tcr; > >>>>> break; > >>>>> - > >>>>> + case SPRN_DECAR: > >>>>> + *spr_val = vcpu->arch.decar; > >>>>> + break; > >>>> DECAR can't be read. Otherwise looks good to me. > >>> DECAR can be read on e500mc cores. So I will make this under > >> CONFIG_KVM_E500MC. > >>> What happens if DECAR is read on non e500mc? Is it treated as NOP or > >>> illegal > >> instruction exception? > >> > >> I would assume the latter. NOPs usually don't happen. If anything, it > >> would return 0. > >> > >> See section 9.4 in the PowerISA: > >> > >> The contents of the Decrementer Auto-Reload Register cannot be read. > >> The contents of bits 32:63 of register RS can be written to the > >> Decrementer Auto- Reload Register using the mtspr instruction. > >> > >> Could you please paste the respective passage of the e500mc manual > >> that declares DECAR as readable? > > I have booke -4 version 1.05. > > There are remarks at 3 place > > > > 1) > > Table 2-1: > > There is remark " DECAR is defined by the architecture to be write-only, > however the e500mc allows it to be read." > > ------------ > > > > 2) > > 2.8.5 Decrementer Auto-Reload Register (DECAR) > > > > "For e500V4, the DECAR can be read in hypervisor state, although the > > architecture defines it as a write-only register." > > -------------- > > > > 3) > > Table 4.37 > > > > Hypervisor Privilege on Read - Yes > > Hypervisor Privilege on Write - Yes > > > > Remark: e500mc allows reading of DECAR although Power ISA does not define it. > > ---------------- > > > > I verified with my unit test that reading DECAR traps in KVM on e500mc. > > Alrighty, so how about putting the read into e500_emulate.c then? Ok > What does e500v2 do here? mfspr(DECAR) works ok e500v2 :), while spec says it is write-only. We should emulate DECAR as per specifications documented . Right? So we will not support trap and emulate for e500v2. Thanks -Bharat > > > Alex > -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
