Re: [PATCH v3 20/39] xen/riscv: resolve the faulting guest physical address

[Baptiste Le Duc <baptiste.le-duc@xxxxxxxxxx>]

> Recover the guest physical address from htval and stval. On a guest-page
> fault to hypervisor, htval holds the guest physical address shifted
> right by 2, so that an address wider than HSXLEN fits, and stval holds
> the faulting guest virtual address. The shift is done on paddr_t rather
> than on the raw register: a guest physical address is 34 bits wide on
> RV32 with Sv32x4, so shifting an XLEN-wide value would drop its top two
> bits.
Nit: "The shift" reads as the right shift just described, while what is meant
is shifting htval back left by 2 to recover the address. Could you say so
explicitly?
Something like:

````
Shift htval back left by 2 and take the two low bits from stval. htval
is first converted to paddr_t, then shifted: a guest physical address is
34 bits wide on RV32 with Sv32x4, so shifting the XLEN-wide register
itself would drop the top two bits.
```

Reviewed-by: Baptiste Le Duc <baptiste.le-duc@xxxxxxxxxx>

-- 
Baptiste Le Duc <baptiste.le-duc@xxxxxxxxxx>