[PATCH 09/12] KVM: PPC: Book3S HV nestedv2: Do not call H_COPY_TOFROM_GUEST

[Vaibhav Jain]

Hi Aneesh,

Thanks for looking into this patch. My responses inline:

"Aneesh Kumar K.V (IBM)" <aneesh.kumar at kernel.org> writes:

<snip>
> May be we should use
> firmware_has_feature(FW_FEATURE_H_COPY_TOFROM_GUEST))?
>
> the nestedv2 can end up using the above hcall if it is supported by the
> hypervisor right? In its absence we will have to translate the guest ea
> using xlate and then use kvm_guest_read to read location using the guest
> real address right? That xlate will also involves multiple kvm_guest_read.
>
>
Yes, Agreed and thats a nice suggestion. However ATM the hypervisor
supporting Nestedv2 doesnt have support for this hcall. In future once
we have support for this hcall for nestedv2 from the hypervisor we can
replace this branch with a firmware_has_feature() test.

>> Signed-off-by: Jordan Niethe <jniethe5 at gmail.com>
>> ---
>>  arch/powerpc/kvm/book3s_64_mmu_radix.c | 3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c
>> index 916af6c153a5..4a1abb9f7c05 100644
>> --- a/arch/powerpc/kvm/book3s_64_mmu_radix.c
>> +++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c
>> @@ -40,6 +40,9 @@ unsigned long __kvmhv_copy_tofrom_guest_radix(int lpid, int pid,
>>  	unsigned long quadrant, ret = n;
>>  	bool is_load = !!to;
>>  
>> +	if (kvmhv_is_nestedv2())
>> +		return H_UNSUPPORTED;
>> +
>>  	/* Can't access quadrants 1 or 2 in non-HV mode, call the HV to do it */
>>  	if (kvmhv_on_pseries())
>>  		return plpar_hcall_norets(H_COPY_TOFROM_GUEST, lpid, pid, eaddr,
>> -- 
>> 2.42.0

-- 
Cheers
~ Vaibhav