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Re: [Qemu-devel] [PATCH] target-arm: Fix translation level on early tran

From: Sergey Fedorov
Subject: Re: [Qemu-devel] [PATCH] target-arm: Fix translation level on early translation faults
Date: Thu, 3 Mar 2016 17:48:21 +0300
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1

On 03.03.2016 16:49, Peter Maydell wrote:
> On 2 March 2016 at 19:19, Sergey Fedorov <address@hidden> wrote:
>> On 02.03.2016 21:04, Sergey Sorokin wrote:
>>> Qemu reports translation fault on 1st level instead of 0th level in case of
>>> AArch64 address translation if the translation table walk is disabled or
>>> the address is in the gap between the two regions.
>> It's probably not a very clear description in the commit message. IIUC,
>> level 0 fault is reported in case of any fault from TTBR in AArch64 state.
> Yes (though you mean "under an AArch64 translation regime"). Conversely, the
> only fault reported at level 0 under an AArch32 translation regime is
> the AddressSize fault (for bad addresses in TTBR0/1), which we don't
> currently implement.
> There's also a code path later in the function that does
>     level = va_size == 64 ? 0 : 1;
> but I'm not sure it's worth rearranging that code to avoid the
> duplication of "what level do we report this kind of fault at?".

Right, but actually I think this patch is going to fix the two "goto
do_fault" cases which can happen before this "level = va_size == 64 ? 0
: 1", namely the EDP check and the check for virtual address which is in
the gap between TTBR0 and TTBR1 regions.

Best regards,

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