Re: [Qemu-devel] [PATCH RFC 3/5] softmmu: add a tlb_vaddr_to_host_fill function

[Aurelien Jarno <aurelien@aurel32.net>]

On 2015-06-02 13:26, Aurelien Jarno wrote:
> The softmmu code already provides a tlb_vaddr_to_host function, which
> returns the host address corresponding to a guest virtual address,
> *if it is already in the QEMU MMU TLB*.
> 
> This patch is an attempt to have a function which try to fill the TLB
> entry if it is not already in the QEMU MMU TLB, possibly trigger a guest
> fault. It can be used directly in helpers. For that it creates a common
> function with a boolean to tell if the TLB needs to be filled or not. If
> yes, it causes tlb_fill, which might trigger an exception or succeed in
> which case the tlbentry pointer need to be reloaded.
> 
> I also had to change the MMIO test part. It seems that in write mode
> some TLB entries are filled with TLB_NOTDIRTY. They are caught by the
> MMIO test and a NULL pointer is returned instead. I am not sure of my
> change, but I guess the current softmmu code has the same issue.

It looks like we have to go through the MMIO functions to get the
TLB_NOTDIRTY bit cleaned correctly. This is something we don't want for
probe_write, so we definitely want two different functions.

-- 
Aurelien Jarno                          GPG: 4096R/1DDD8C9B
aurelien@aurel32.net                 http://www.aurel32.net