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Re: [Qemu-devel] [PATCH v1 07/10] target-arm: Supress the use of TTBR1 f
From: |
Edgar E. Iglesias |
Subject: |
Re: [Qemu-devel] [PATCH v1 07/10] target-arm: Supress the use of TTBR1 for S2 translations |
Date: |
Tue, 8 Sep 2015 16:57:55 +0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Tue, Sep 08, 2015 at 03:50:34PM +0100, Peter Maydell wrote:
> On 8 September 2015 at 15:42, Edgar E. Iglesias
> <address@hidden> wrote:
> > On Tue, Sep 08, 2015 at 03:32:36PM +0100, Peter Maydell wrote:
> >> On 3 September 2015 at 21:14, Edgar E. Iglesias
> >> <address@hidden> wrote:
> >> > From: "Edgar E. Iglesias" <address@hidden>
> >> >
> >> > Stage-2 MMU translations do not use TTBR1.
> >> >
> >> > Signed-off-by: Edgar E. Iglesias <address@hidden>
> >> > ---
> >> > target-arm/helper.c | 5 +++++
> >> > 1 file changed, 5 insertions(+)
> >> >
> >> > diff --git a/target-arm/helper.c b/target-arm/helper.c
> >> > index 9ea9719..66b3fed 100644
> >> > --- a/target-arm/helper.c
> >> > +++ b/target-arm/helper.c
> >> > @@ -6372,6 +6372,11 @@ static bool get_phys_addr_lpae(CPUARMState *env,
> >> > target_ulong address,
> >> > }
> >> > }
> >> >
> >> > + /* Stage2 translations do not use TTBR1. */
> >> > + if (mmu_idx == ARMMMUIdx_S2NS) {
> >> > + ttbr1_valid = false;
> >> > + }
> >> > +
> >>
> >> I think this is unnecessary, because we've already set ttbr1_valid
> >> to false in the previous chunk of code for the case where el == 2
> >> (as it is for stage 2 translations).
> >
> > I think we may be confused here.
> >
> > Note S2NS translations are controlled by EL2 but apply to NS EL0 and EL1.
>
> Yep. el is the result of regime_el(), which returns what the ARM ARM
> calls "the EL that the translation regime is controlled from".
> In particular, we do things this way because it's the register width
> of the controlling EL that determines whether the translation
> regime is 64 bit, whether the TCR/TTBR/etc registers are the 64-bit
> forms or not, etc.
OK, I see. I'll have another look at this...
Thanks!
Edgar
- Re: [Qemu-devel] [PATCH v1 04/10] target-arm: Add VTCR_EL2, (continued)
[Qemu-devel] [PATCH v1 08/10] target-arm: Supress EPD for S2, EL2 and EL3 translations, Edgar E. Iglesias, 2015/09/03
[Qemu-devel] [PATCH v1 09/10] target-arm: Add VPIDR_EL2, Edgar E. Iglesias, 2015/09/03
[Qemu-devel] [PATCH v1 10/10] target-arm: Add VMPIDR_EL2, Edgar E. Iglesias, 2015/09/03
Re: [Qemu-devel] [PATCH v1 00/10] arm: Steps towards EL2 support round 4, Peter Maydell, 2015/09/08