Re: [Qemu-arm] [Qemu-devel] [PATCH 4/7] target/arm: Make v7M exception entry stack push check MPU

[Peter Maydell]

On 3 February 2018 at 21:21, Richard Henderson
<address@hidden> wrote:
> On 01/30/2018 07:02 AM, Peter Maydell wrote:
>> +    if (get_phys_addr(env, addr, MMU_DATA_STORE, mmu_idx, &physaddr,
>> +                      &attrs, &prot, &page_size, &fi, NULL)) {
>
> Given that you know you're going to call this at least 8 times in a row,
> probably with all operations on the same page, it is worth querying the qemu
> tlb first, and when that fails but the lookup succeeds, installing the result
> into the tlb?

get_phys_addr and address_space_stl_le don't touch the TLB though?
We could in theory do a get_phys_addr() once per-page rather than
doing it all 8 times though, yes.

But yes, I figured I'd write the straightforward code -- M class
CPU h/w all runs much slower than the host CPU anyway so we
probably have some overhead to play with. If anybody ever
complains maybe we can profile it :-)

thanks
-- PMM