Re: [Xen-devel] [PATCH v2 4/9] xen: arm: correctly handle vtimer traps from userspace

[Julien Grall <julien.grall@xxxxxxxxxx>]

Hi Ian,

On 10/02/2015 12:45, 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.
Should not we take care of CNTP_CVAL_EL0 too? It seems that we don't 
even trap it for now...
[..]

> @@ -2062,8 +2053,7 @@ asmlinkage void do_trap_hypervisor(struct cpu_user_regs 
> *regs)
>           do_cp15_32(regs, hsr);
>           break;
>       case HSR_EC_CP15_64:
> -        if ( !is_32bit_domain(current->domain) )
> -            goto bad_trap;
> +        BUG_ON(!psr_mode_is_32bit(regs->cpsr));
You should mention the change from if ( .... ) goto bad_trap to BUG_ON( 
... ) in the commit message.
Although, I think the debug message in bad_trap is useful to keep. It 
may be handy to have the HSR and the guest stack trace printed if Xen 
hit the condition.
[..]

> @@ -238,7 +250,7 @@ static int vtimer_emulate_cp64(struct cpu_user_regs *regs, 
> union hsr hsr)
>       switch ( hsr.bits & HSR_CP64_REGS_MASK )
>       {
>       case HSR_CPREG64(CNTPCT):
> -        if (!vtimer_cntpct(regs, &x, cp64.read))
> +        if ( !vtimer_cntpct(regs, &x, cp64.read) )
I would mention the coding style change in the commit message.

Regards,

--
Julien Grall

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