[PATCH 2/2] arm64: kvm: upgrade csselr and ccsidr to 64-bit values

[Sudeep Holla]

On 23/01/17 21:08, Christoffer Dall wrote:
> On Fri, Jan 20, 2017 at 10:50:10AM +0000, Sudeep Holla wrote:
>> csselr and ccsidr are treated as 64-bit values already elsewhere in the
>> kernel. It also aligns well with the architecture extensions that allow
>> 64-bit format for ccsidr.
>>
>> This patch upgrades the existing accesses to csselr and ccsidr from
>> 32-bit to 64-bit in preparation to add support to those extensions.
>>
>> Cc: Christoffer Dall <christoffer.dall at linaro.org>
>> Cc: Marc Zyngier <marc.zyngier at arm.com>
>> Signed-off-by: Sudeep Holla <sudeep.holla at arm.com>
>> ---
>>  arch/arm64/kvm/sys_regs.c | 18 +++++++++---------
>>  1 file changed, 9 insertions(+), 9 deletions(-)
>>
>> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
>> index 5dca1f10340f..a3559a8a2b0c 100644
>> --- a/arch/arm64/kvm/sys_regs.c
>> +++ b/arch/arm64/kvm/sys_regs.c

[..]

>> @@ -2004,8 +2004,8 @@ static int demux_c15_get(u64 id, void __user *uaddr)
>>  
>>  static int demux_c15_set(u64 id, void __user *uaddr)
>>  {
>> -	u32 val, newval;
>> -	u32 __user *uval = uaddr;
>> +	u64 val, newval;
>> +	u64 __user *uval = uaddr;
> 
> Doesn't converting these uval pointers to u64 cause us to break the ABI
> as we'll now be reading/writing 64-bit values to userspace with the
> get_user and put_user following the declarations?
> 

Yes, I too have similar concern. IIUC it is always read via kvm_one_reg
structure. I could not find any specific user for this register to cross
check.

-- 
Regards,
Sudeep