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

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

[Peter Maydell]

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 <peter.maydell@linaro.org>
---
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

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

[Stefano Stabellini]

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 <peter.maydell@linaro.org>

Tested-by: Stefano Stabellini <sstabellini@kernel.org>


> ---
> 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
> 
> 

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

[Alex Bennée]

Peter Maydell <peter.maydell@linaro.org> writes:

> 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 <peter.maydell@linaro.org>

As far as it goes it seems reasonable:

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

> ---
> 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.


--
Alex Bennée

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 <peter.maydell@linaro.org>
> 
> Tested-by: Stefano Stabellini <sstabellini@kernel.org>

Hi,

This looks like an OK workaround for the moment:
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>

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
> > 
> >