On 30 January 2015 at 02:03, Edgar E. Iglesias <edgar.igles...@gmail.com> wrote:
> On Thu, Jan 29, 2015 at 06:55:15PM +0000, Peter Maydell wrote:
>> Now we have the mmu_idx in get_phys_addr(), use it correctly to
>> determine the behaviour of virtual to physical address translations,
>> rather than using just an is_user flag and the current CPU state.
>>
>> Some TODO comments have been added to indicate where changes will
>> need to be made to add EL2 and 64-bit EL3 support.
>> - /* This will go away when we handle mmu_idx properly here */
>> - int is_user = (mmu_idx == ARMMMUIdx_S12NSE0 ||
>> - mmu_idx == ARMMMUIdx_S1SE0 ||
>> - mmu_idx == ARMMMUIdx_S1NSE0);
>> + if (mmu_idx == ARMMMUIdx_S12NSE0 || mmu_idx == ARMMMUIdx_S12NSE1) {
>> + /* TODO: when we support EL2 we should here call ourselves
>> recursively
>> + * to do the stage 1 and then stage 2 translations. The ldl_phys
>> + * calls for stage 1 will also need changing.
>> + * For non-EL2 CPUs a stage1+stage2 translation is just stage 1.
>> + */
>> + assert(!arm_feature(env, ARM_FEATURE_EL2));
>> + mmu_idx += ARMMMUIdx_S1NSE0;
>
> I'm not sure I understand this. Did you mean the following?
> mmu_idx = ARMMMUIdx_S1NSE0;
No. This code is handling "we asked for a stage1+2 EL0 or EL1
lookup but we don't have EL2". In this case these degrade
to the equivalent stage-1-only lookups:
S12NSE0 -> S1NSE0
S12NSE1 -> S1NSE1
We're relying on S12NSE0 being zero and the E0/E1 indexes
being consecutive on both sides.
> Maybe you can relax the assert to check for FEATURE_EL2 and hcr_el2 & HCR_VM ?
> And not change the mmu_idx.
The assert is here to say "if you want to implement EL2 there
is work to do here". For EL2, this is going to look
something like:
if (arm_feature(env, ARM_FEATURE_EL2 && (hcr_el2 & HCR_VM)) {
/* stage 2 exists and is enabled */
hwaddr ipa;
get_phys_addr(env, addr, &ipa, ..., stage 1 mmuidx, ...);
handle stage 1 faults;
get_phys_addr(env, ipa, &physaddr, ...., stage 2 mmuidx, ...);
handle stage 2 faults;
combine protection etc info from stage 1 and stage 2;
return final physaddr for combined lookup;
}
That's quite a bit of extra code, so it's deferred til we
actually implement EL2, and in the meantime we assert as a
marker for "if you hit this you need to implement all that".
-- PMM
