Re: Re: [PATCH v5 1/4] KVM: selftests: Add KVM selftests header files for LoongArch

[zhaotianrui]

在 2023/12/13 上午1:18, Sean Christopherson 写道:
> On Tue, Dec 12, 2023, zhaotianrui wrote:
> > Hi, Sean:
> >
> > I want to change the definition of  DEFAULT_GUEST_TEST_MEM in the common
> > file "memstress.h", like this:
> >
> >   /* Default guest test virtual memory offset */
> > +#ifndef DEFAULT_GUEST_TEST_MEM
> >   #define DEFAULT_GUEST_TEST_MEM		0xc0000000
> > +#endif
> >
> > As this address should be re-defined in LoongArch headers.
>
> Why?  E.g. is 0xc0000000 unconditionally reserved, not guaranteed to be valid,
> something else?
>
> > So, do you have any suggesstion?
>
> Hmm, I think ideally kvm_util_base.h would define a range of memory that can be
> used by tests for arbitrary data.  Multiple tests use 0xc0000000, which is not
> entirely arbitrary, i.e. it doesn't _need_ to be 0xc0000000, but 0xc0000000 is
> convenient because it's 32-bit addressable and doesn't overlap reserved areas in
> other architectures.
Thanks for your explanation, and LoongArch want to define 
DEFAULT_GUEST_TEST_MEM to 0x130000000. As default base address for 
application loading is 0x120000000, DEFAULT_GUEST_TEST_MEM should be 
larger than app loading address, so that PER_VCPU_MEM_SIZE can be large 
enough, and kvm selftests app size is smaller than 256M in generic.

Thanks
Tianrui Zhao