Re: [PATCH v3 7/9] KVM: PPC: Ultravisor: Restrict LDBAR access

[Claudio Carvalho <cclaudio@linux.ibm.com>]

On 6/7/19 1:48 AM, Madhavan Srinivasan wrote:
>
> On 06/06/19 11:06 PM, Claudio Carvalho wrote:
>> When the ultravisor firmware is available, it takes control over the
>> LDBAR register. In this case, thread-imc updates and save/restore
>> operations on the LDBAR register are handled by ultravisor.
>>
>> Signed-off-by: Claudio Carvalho <cclaudio@linux.ibm.com>
>> Signed-off-by: Ram Pai <linuxram@us.ibm.com>
>> ---
>>   arch/powerpc/kvm/book3s_hv_rmhandlers.S   | 2 ++
>>   arch/powerpc/platforms/powernv/idle.c     | 6 ++++--
>>   arch/powerpc/platforms/powernv/opal-imc.c | 7 +++++++
>>   3 files changed, 13 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
>> b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
>> index f9b2620fbecd..cffb365d9d02 100644
>> --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
>> +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
>> @@ -375,8 +375,10 @@ BEGIN_FTR_SECTION
>>       mtspr    SPRN_RPR, r0
>>       ld    r0, KVM_SPLIT_PMMAR(r6)
>>       mtspr    SPRN_PMMAR, r0
>> +BEGIN_FW_FTR_SECTION_NESTED(70)
>>       ld    r0, KVM_SPLIT_LDBAR(r6)
>>       mtspr    SPRN_LDBAR, r0
>> +END_FW_FTR_SECTION_NESTED(FW_FEATURE_ULTRAVISOR, 0, 70)
>>       isync
>>   FTR_SECTION_ELSE
>>       /* On P9 we use the split_info for coordinating LPCR changes */
>> diff --git a/arch/powerpc/platforms/powernv/idle.c
>> b/arch/powerpc/platforms/powernv/idle.c
>> index c9133f7908ca..fd62435e3267 100644
>> --- a/arch/powerpc/platforms/powernv/idle.c
>> +++ b/arch/powerpc/platforms/powernv/idle.c
>> @@ -679,7 +679,8 @@ static unsigned long power9_idle_stop(unsigned long
>> psscr, bool mmu_on)
>>           sprs.ptcr    = mfspr(SPRN_PTCR);
>>           sprs.rpr    = mfspr(SPRN_RPR);
>>           sprs.tscr    = mfspr(SPRN_TSCR);
>> -        sprs.ldbar    = mfspr(SPRN_LDBAR);
>> +        if (!firmware_has_feature(FW_FEATURE_ULTRAVISOR))
>> +            sprs.ldbar    = mfspr(SPRN_LDBAR);
>>
>>           sprs_saved = true;
>>
>> @@ -762,7 +763,8 @@ static unsigned long power9_idle_stop(unsigned long
>> psscr, bool mmu_on)
>>       mtspr(SPRN_PTCR,    sprs.ptcr);
>>       mtspr(SPRN_RPR,        sprs.rpr);
>>       mtspr(SPRN_TSCR,    sprs.tscr);
>> -    mtspr(SPRN_LDBAR,    sprs.ldbar);
>> +    if (!firmware_has_feature(FW_FEATURE_ULTRAVISOR))
>> +        mtspr(SPRN_LDBAR,    sprs.ldbar);
>>
>>       if (pls >= pnv_first_tb_loss_level) {
>>           /* TB loss */
>> diff --git a/arch/powerpc/platforms/powernv/opal-imc.c
>> b/arch/powerpc/platforms/powernv/opal-imc.c
>> index 1b6932890a73..e9b641d313fb 100644
>> --- a/arch/powerpc/platforms/powernv/opal-imc.c
>> +++ b/arch/powerpc/platforms/powernv/opal-imc.c
>> @@ -254,6 +254,13 @@ static int opal_imc_counters_probe(struct
>> platform_device *pdev)
>>       bool core_imc_reg = false, thread_imc_reg = false;
>>       u32 type;
>>
>> +    /*
>> +     * When the Ultravisor is enabled, it is responsible for thread-imc
>> +     * updates
>> +     */
>
> Would prefer the comment to be "Disable IMC devices, when Ultravisor is
> enabled"
> Rest looks good.
> Acked-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>


Thanks Maddy. I applied that change to the next version.

Claudio


>
>> +    if (firmware_has_feature(FW_FEATURE_ULTRAVISOR))
>> +        return -EACCES;
>> +
>>       /*
>>        * Check whether this is kdump kernel. If yes, force the engines to
>>        * stop and return.