Re: [Qemu-devel] [PATCH] arm: check regime, not current state, for ATS write PAR format

[Edgar E. Iglesias]

On Fri, Nov 03, 2017 at 10:36:37AM -0700, Stefano Stabellini wrote:
> On Fri, 3 Nov 2017, Peter Maydell wrote:
> > In do_ats_write(), rather than using extended_addresses_enabled() to
> > decide whether the value we get back from get_phys_addr() is a 64-bit
> > format PAR or a 32-bit one, use arm_s1_regime_using_lpae_format().
> > 
> > This is not really the correct answer, because the PAR format
> > depends on the AT instruction being used, not just on the
> > translation regime. However getting this correct requires a
> > significant refactoring, so that get_phys_addr() returns raw
> > information about the fault which the caller can then assemble
> > into a suitable FSR/PAR/syndrome for its purposes, rather than
> > get_phys_addr() returning a pre-formatted FSR.
> > 
> > However this change at least improves the situation by making
> > the PAR work correctly for address translation operations done
> > at AArch64 EL2 on the EL2 translation regime. In particular,
> > this is necessary for Xen to be able to run in our emulation,
> > so this seems like a safer interim fix given that we are in freeze.
> > 
> > Signed-off-by: Peter Maydell <address@hidden>
> 
> Tested-by: Stefano Stabellini <address@hidden>

Hi,

This looks like an OK workaround for the moment:
Reviewed-by: Edgar E. Iglesias <address@hidden>

Cheers,
Edgar

> 
> 
> > ---
> > I guess I should have a go at the "correct answer" I sketch
> > above, but no promises about when I'll get time for that :-(
> > 
> >  target/arm/helper.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/target/arm/helper.c b/target/arm/helper.c
> > index 96113fe..37af750 100644
> > --- a/target/arm/helper.c
> > +++ b/target/arm/helper.c
> > @@ -2162,7 +2162,7 @@ static uint64_t do_ats_write(CPUARMState *env, 
> > uint64_t value,
> >  
> >      ret = get_phys_addr(env, value, access_type, mmu_idx,
> >                          &phys_addr, &attrs, &prot, &page_size, &fsr, &fi);
> > -    if (extended_addresses_enabled(env)) {
> > +    if (arm_s1_regime_using_lpae_format(env, mmu_idx)) {
> >          /* fsr is a DFSR/IFSR value for the long descriptor
> >           * translation table format, but with WnR always clear.
> >           * Convert it to a 64-bit PAR.
> > -- 
> > 2.7.4
> > 
> >