Re: [kvm-unit-tests PATCH v7 06/13] arm/arm64: ITS: Introspection tests

[Zenghui Yu]

Hi Drew,

On 2020/3/30 17:11, Andrew Jones wrote:
> On Mon, Mar 30, 2020 at 10:46:57AM +0200, Auger Eric wrote:
> > Hi Zenghui,
> >
> > On 3/30/20 10:30 AM, Zenghui Yu wrote:

[...]

> > > Otherwise I think we will end-up with memory corruption when writing
> > > the command queue.  But it seems that everything just works fine ...
> > > So I'm really confused here :-/
> > I was told by Paolo that the VA/PA memory map is flat in kvmunit test.
>
> What does flat mean? kvm-unit-tests, at least arm/arm64, does prepare
> an identity map of all physical memory, which explains why the above
> is working. It's doing virt_to_phys(some-virt-addr), which gets a
> phys addr, but when the ITS uses it as a virt addr it works because
> we *also* have a virt addr == phys addr mapping in the default page
> table, which is named "idmap" for good reason.

Thanks for the explanation :-). I will have a look at the arm/arm64 mm
code to learn it.


Thanks,
Zenghui