Re: [PATCH v2 2/2] s390/kvm: VSIE: fix MVPG handling for prefixing and MSO

From: Christian Borntraeger <borntraeger@de.ibm.com>
To: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>,
	linux-kernel@vger.kernel.org, frankja@linux.ibm.com,
	cohuck@redhat.com, kvm@vger.kernel.org,
	linux-s390@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH v2 2/2] s390/kvm: VSIE: fix MVPG handling for prefixing and MSO
Date: Tue, 23 Mar 2021 16:34:37 +0100	[thread overview]
Message-ID: <9e0e7fc1-e6c4-0329-aa42-f8ffc30f2c71@de.ibm.com> (raw)
In-Reply-To: <20210323162152.3356dc19@ibm-vm>

On 23.03.21 16:21, Claudio Imbrenda wrote:
> On Tue, 23 Mar 2021 16:16:18 +0100
> Christian Borntraeger <borntraeger@de.ibm.com> wrote:
> 
>> On 23.03.21 16:11, David Hildenbrand wrote:
>>> On 23.03.21 16:07, Christian Borntraeger wrote:
>>>>
>>>>
>>>> On 22.03.21 15:05, Claudio Imbrenda wrote:
>>>>> Prefixing needs to be applied to the guest real address to
>>>>> translate it into a guest absolute address.
>>>>>
>>>>> The value of MSO needs to be added to a guest-absolute address in
>>>>> order to obtain the host-virtual.
>>>>>
>>>>> Fixes: 223ea46de9e79 ("s390/kvm: VSIE: correctly handle MVPG when
>>>>> in VSIE") Cc: stable@vger.kernel.org
>>>>> Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
>>>>> Reported-by: Janosch Frank <frankja@linux.ibm.com>
>>>>> ---
>>>>>     arch/s390/kvm/vsie.c | 6 +++++-
>>>>>     1 file changed, 5 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
>>>>> index 48aab6290a77..ac86f11e46dc 100644
>>>>> --- a/arch/s390/kvm/vsie.c
>>>>> +++ b/arch/s390/kvm/vsie.c
>>>>> @@ -1002,7 +1002,7 @@ static u64 vsie_get_register(struct
>>>>> kvm_vcpu *vcpu, struct vsie_page *vsie_page, static int
>>>>> vsie_handle_mvpg(struct kvm_vcpu *vcpu, struct vsie_page
>>>>> *vsie_page) { struct kvm_s390_sie_block *scb_s =
>>>>> &vsie_page->scb_s;
>>>>> -    unsigned long pei_dest, pei_src, src, dest, mask;
>>>>> +    unsigned long pei_dest, pei_src, dest, src, mask, mso,
>>>>> prefix; u64 *pei_block = &vsie_page->scb_o->mcic;
>>>>>         int edat, rc_dest, rc_src;
>>>>>         union ctlreg0 cr0;
>>>>> @@ -1010,9 +1010,13 @@ static int vsie_handle_mvpg(struct
>>>>> kvm_vcpu *vcpu, struct vsie_page *vsie_page) cr0.val =
>>>>> vcpu->arch.sie_block->gcr[0]; edat = cr0.edat &&
>>>>> test_kvm_facility(vcpu->kvm, 8); mask =
>>>>> _kvm_s390_logical_to_effective(&scb_s->gpsw, PAGE_MASK);
>>>>> +    mso = scb_s->mso & ~(1UL << 20);
>>>>              shouldnt that be ~((1UL << 20 ) -1)
> 
> oops
> 
>>>
>>> Looking at shadow_scb(), we can simply take scb_s->mso unmodified.
>>
>> Right, I think I can fix this up (and get rid of the local mso
> 
> I think that's easier/simpler
> 
>> variable) when queueing. Or shall Claudio send a new version of the
>> patch?
> 

queued (with fixup). Please note: can you use "KVM: s390:" instead of "s390/kvm" for the future patches.