Excerpts from Fabiano Rosas's message of March 9, 2021 1:26 am:
> Nicholas Piggin <npiggin@xxxxxxxxx> writes:
>
>> These are already disallowed by H_SET_MODE from the guest, also disallow
>> these by updating LPCR directly.
>>
>> AIL modes can affect the host interrupt behaviour while the guest LPCR
>> value is set, so filter it here too.
>>
>> Suggested-by: Fabiano Rosas <farosas@xxxxxxxxxxxxx>
>> Signed-off-by: Nicholas Piggin <npiggin@xxxxxxxxx>
>> ---
>> arch/powerpc/kvm/book3s_hv.c | 11 +++++++++--
>> arch/powerpc/kvm/book3s_hv_nested.c | 7 +++++--
>> 2 files changed, 14 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
>> index 13bad6bf4c95..c40eeb20be39 100644
>> --- a/arch/powerpc/kvm/book3s_hv.c
>> +++ b/arch/powerpc/kvm/book3s_hv.c
>> @@ -803,7 +803,10 @@ static int kvmppc_h_set_mode(struct kvm_vcpu *vcpu, unsigned long mflags,
>> vcpu->arch.dawrx1 = value2;
>> return H_SUCCESS;
>> case H_SET_MODE_RESOURCE_ADDR_TRANS_MODE:
>> - /* KVM does not support mflags=2 (AIL=2) */
>> + /*
>> + * KVM does not support mflags=2 (AIL=2) and AIL=1 is reserved.
>> + * Keep this in synch with kvmppc_set_lpcr.
>> + */
>> if (mflags != 0 && mflags != 3)
>> return H_UNSUPPORTED_FLAG_START;
>> return H_TOO_HARD;
>> @@ -1667,8 +1670,12 @@ static void kvmppc_set_lpcr(struct kvm_vcpu *vcpu, u64 new_lpcr,
>> * On POWER8 and POWER9 userspace can also modify AIL (alt. interrupt loc.).
>> */
>> mask = LPCR_DPFD | LPCR_ILE | LPCR_TC;
>> - if (cpu_has_feature(CPU_FTR_ARCH_207S))
>> + if (cpu_has_feature(CPU_FTR_ARCH_207S)) {
>> mask |= LPCR_AIL;
>> + /* LPCR[AIL]=1/2 is disallowed */
>> + if ((new_lpcr & LPCR_AIL) && (new_lpcr & LPCR_AIL) != LPCR_AIL_3)
>> + new_lpcr &= ~LPCR_AIL;
>> + }
>> /*
>> * On POWER9, allow userspace to enable large decrementer for the
>> * guest, whether or not the host has it enabled.
>> diff --git a/arch/powerpc/kvm/book3s_hv_nested.c b/arch/powerpc/kvm/book3s_hv_nested.c
>> index 2fe1fea4c934..b496079e02f7 100644
>> --- a/arch/powerpc/kvm/book3s_hv_nested.c
>> +++ b/arch/powerpc/kvm/book3s_hv_nested.c
>> @@ -139,9 +139,12 @@ static void sanitise_hv_regs(struct kvm_vcpu *vcpu, struct hv_guest_state *hr)
>
> We're missing the patch that moves the lpcr setting into
> sanitise_hv_regs.
Oh yes sorry, mistyped the format-patch command.
>>
>> /*
>> * Don't let L1 change LPCR bits for the L2 except these:
>> + * Keep this in sync with kvmppc_set_lpcr.
>> */
>> - mask = LPCR_DPFD | LPCR_ILE | LPCR_TC | LPCR_AIL | LPCR_LD |
>> - LPCR_LPES | LPCR_MER;
>> + mask = LPCR_DPFD | LPCR_ILE | LPCR_TC | LPCR_LD | LPCR_LPES | LPCR_MER;
>
> I think this line's change belongs in patch 33 doesn't it? Otherwise you
> are clearing a bit below that is not present in the mask so it would
> never be used anyway.
Ah yes, thank you. Will fix.
>
>> + /* LPCR[AIL]=1/2 is disallowed */
>> + if ((hr->lpcr & LPCR_AIL) && (hr->lpcr & LPCR_AIL) != LPCR_AIL_3)
>> + hr->lpcr &= ~LPCR_AIL;
>> hr->lpcr = (vc->lpcr & ~mask) | (hr->lpcr & mask);
>>
>> /*
>
