Re: [Xen-devel] [PATCH v4 03/15] xen: arm: correctly handle vtimer traps from userspace

[Julien Grall <julien.grall@xxxxxxxxxx>]

Hi Ian,

On 27/03/15 14:33, Ian Campbell wrote:
> Previously 32-bit userspace on 32-bit kernel and 64-bit userspace on
> 64-bit kernel could access these registers irrespective of whether the
> kernel had configured them to be allowed to. To fix this:
> 
>  - Userspace access to CNTP_CTL_EL0 and CNTP_TVAL_EL0 should be gated
>    on CNTKCTL_EL1.EL0PTEN.
>  - Userspace access to CNTPCT_EL0 should be gated on
>    CNTKCTL_EL1.EL0PCTEN.
> 
> When we do not handle an access we now silently inject an undef even
> in debug mode since the debugging messages are not helpful (we have
> handled the access, by explicitly choosing not to).
> 
> The usermode accessibility check is rather repetitive, so a helper
> macro is introduced.
> 
> Since HSR_EC_CP15_64 cannot be taken from a guest in AArch64 mode
> except due to a hardware bug switch the associated check to a BUG_ON
> (which will be switched to something more appropriate in a subsequent
> patch)
> 
> Fix a coding style issue in HSR_CPREG64(CNTPCT) while touching similar
> code.
> 
> Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
Reviewed-by: Julien Grall <julien.grall@xxxxxxxxxx>

Regards,

-- 
Julien Grall

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