Re: [GIT PULL 2/2] KVM: s390/mm: try a cow on read only pages for key ops

[Paolo Bonzini <pbonzini@redhat.com>]

Il 27/08/2014 09:13, Christian Borntraeger ha scritto:
> On 27/08/14 05:06, Ben Hutchings wrote:
>> On Mon, 2014-08-25 at 15:10 +0200, Christian Borntraeger wrote:
>>> The PFMF instruction handler  blindly wrote the storage key even if
>>> the page was mapped R/O in the host. Lets try a COW before continuing
>>> and bail out in case of errors.
>>>
>>> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
>>> Reviewed-by: Dominik Dingel <dingel@linux.vnet.ibm.com>
>>> Cc: stable@vger.kernel.org
>>> ---
>>>  arch/s390/mm/pgtable.c | 10 ++++++++++
>>>  1 file changed, 10 insertions(+)
>>>
>>> diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
>>> index 19daa53..5404a62 100644
>>> --- a/arch/s390/mm/pgtable.c
>>> +++ b/arch/s390/mm/pgtable.c
>>> @@ -986,11 +986,21 @@ int set_guest_storage_key(struct mm_struct *mm, unsigned long addr,
>>>  	pte_t *ptep;
>>>  
>>>  	down_read(&mm->mmap_sem);
>>> +retry:
>>>  	ptep = get_locked_pte(current->mm, addr, &ptl);
>>>  	if (unlikely(!ptep)) {
>>>  		up_read(&mm->mmap_sem);
>>>  		return -EFAULT;
>>>  	}
>>> +	if (!(pte_val(*ptep) & _PAGE_INVALID) &&
>>> +	     (pte_val(*ptep) & _PAGE_PROTECT)) {
>>> +			pte_unmap_unlock(*ptep, ptl);
>>> +			if (fixup_user_fault(current, mm, addr, FAULT_FLAG_WRITE)) {
>>> +				up_read(&mm->mmap_sem);
>>> +				return -EFAULT;
>>> +			}
>>> +			goto retry;
>>> +		}
>>
>> Every line below the first 'if' is indented one tab stop too far.
>>
>> Ben.
>>
>>>  	new = old = pgste_get_lock(ptep);
>>>  	pgste_val(new) &= ~(PGSTE_GR_BIT | PGSTE_GC_BIT |
>>
> 
> Hmm, indeed. Drat. Paolo, do you want a revert, resend?

Just send a trivial patch to fix up the formatting.

Paolo