Re: [RFC PATCH 1/2] KVM: selftests: Add a macro to get string of vm_mem_backing_src_type

[wangyanan (Y)]

On 2021/2/9 2:13, Ben Gardon wrote:
> On Mon, Feb 8, 2021 at 1:08 AM Yanan Wang <wangyanan55@xxxxxxxxxx> wrote:
> > Add a macro to get string of the backing source memory type, so that
> > application can add choices for source types in the help() function,
> > and users can specify which type to use for testing.
> Coincidentally, I sent out a change last week to do the same thing:
> "KVM: selftests: Add backing src parameter to dirty_log_perf_test"
> (https://lkml.org/lkml/2021/2/2/1430)
> Whichever way this ends up being implemented, I'm happy to see others
> interested in testing different backing source types too.

Thanks Ben! I have a little question here.

Can we just present three IDs (0/1/2) but not strings for users to 
choose which backing_src_type to use like the way of guest modes,

which I think can make cmdlines more consise and easier to print. And is 
it better to make a universal API to get backing_src_strings

like Sean have suggested, so that the API can be used elsewhere ?

> > Signed-off-by: Yanan Wang <wangyanan55@xxxxxxxxxx>
> > ---
> >   tools/testing/selftests/kvm/include/kvm_util.h | 3 +++
> >   tools/testing/selftests/kvm/lib/kvm_util.c     | 8 ++++++++
> >   2 files changed, 11 insertions(+)
> >
> > diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
> > index 5cbb861525ed..f5fc29dc9ee6 100644
> > --- a/tools/testing/selftests/kvm/include/kvm_util.h
> > +++ b/tools/testing/selftests/kvm/include/kvm_util.h
> > @@ -69,7 +69,9 @@ enum vm_guest_mode {
> >   #define PTES_PER_MIN_PAGE      ptes_per_page(MIN_PAGE_SIZE)
> >
> >   #define vm_guest_mode_string(m) vm_guest_mode_string[m]
> > +#define vm_mem_backing_src_type_string(s) vm_mem_backing_src_type_string[s]
> >   extern const char * const vm_guest_mode_string[];
> > +extern const char * const vm_mem_backing_src_type_string[];
> >
> >   struct vm_guest_mode_params {
> >          unsigned int pa_bits;
> > @@ -83,6 +85,7 @@ enum vm_mem_backing_src_type {
> >          VM_MEM_SRC_ANONYMOUS,
> >          VM_MEM_SRC_ANONYMOUS_THP,
> >          VM_MEM_SRC_ANONYMOUS_HUGETLB,
> > +       NUM_VM_BACKING_SRC_TYPES,
> >   };
> >
> >   int kvm_check_cap(long cap);
> > diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
> > index fa5a90e6c6f0..a9b651c7f866 100644
> > --- a/tools/testing/selftests/kvm/lib/kvm_util.c
> > +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
> > @@ -165,6 +165,14 @@ const struct vm_guest_mode_params vm_guest_mode_params[] = {
> >   _Static_assert(sizeof(vm_guest_mode_params)/sizeof(struct vm_guest_mode_params) == NUM_VM_MODES,
> >                 "Missing new mode params?");
> >
> > +const char * const vm_mem_backing_src_type_string[] = {
> > +       "VM_MEM_SRC_ANONYMOUS        ",
> > +       "VM_MEM_SRC_ANONYMOUS_THP    ",
> > +       "VM_MEM_SRC_ANONYMOUS_HUGETLB",
> > +};
> > +_Static_assert(sizeof(vm_mem_backing_src_type_string)/sizeof(char *) == NUM_VM_BACKING_SRC_TYPES,
> > +              "Missing new source type strings?");
> > +
> >   /*
> >    * VM Create
> >    *
> > --
> > 2.23.0
> .