Re: [Qemu-devel] [PATCH] riscv: rv32: Root page table address can be larger than 32-bit

[Palmer Dabbelt]

On Thu, Aug 1, 2019 at 7:58 AM Bin Meng <address@hidden> wrote:

> On Thu, Aug 1, 2019 at 10:16 PM Richard Henderson
> <address@hidden> wrote:
> >
> > On 7/31/19 6:53 PM, Bin Meng wrote:
> > > I am not sure how (idx * ptesize) could overflow. It represents the
> > > offset by a page table which is [0, 4096).
> >
> > You're right, I mis-read what was going on there.
> >
> > However, lower down, "target_ulong ppn" needs to be promoted to hwaddr,
> so that
> >
> >     ppn = pte >> PTE_PPN_SHIFT;
> >     ...
> >     base = ppn << PGSHIFT;
> >
> > does not overflow.  (Which is the part of the page table walk that I
> thought I
> > had gleaned from the patch without actually reading the entire function.)
>
> Ah, yes. ppn should be promoted. Thanks for the review!
>

Did I miss a v2?