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Re: [PATCH] target/arm: Use signed quantity to represent VMSAv8-64 trans
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From: |
Ard Biesheuvel |
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Subject: |
Re: [PATCH] target/arm: Use signed quantity to represent VMSAv8-64 translation level |
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Date: |
Mon, 21 Nov 2022 20:02:34 +0100 |
On Mon, 21 Nov 2022 at 19:51, Peter Maydell <peter.maydell@linaro.org> wrote:
>
> On Mon, 21 Nov 2022 at 17:43, Ard Biesheuvel <ardb@kernel.org> wrote:
> >
> > The LPA2 extension implements 52-bit virtual addressing for 4k and 16k
> > translation granules, and for the former, this means an additional level
> > of translation is needed. This means we start counting at -1 instead of
> > 0 when doing a walk, and so 'level' is now a signed quantity, and should
> > be typed as such. So turn it from uint32_t into int32_t.
> >
>
> Does this cause any visible wrong behaviour, or is it just
> a cleanup thing ?
>
No, 5 level paging is completely broken because of this, given that
the 'level < 3' tests give the wrong result for (uint32_t)-1