Introduce arch specific API: kvm_selftest_arch_init to allow each arch to
handle initialization before running any selftest logic.

Suggested-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
Reviewed-by: Peter Gonda <pgonda@google.com>
Signed-off-by: Vishal Annapurve <vannapurve@google.com>
---
 .../selftests/kvm/include/kvm_util_base.h      |  5 +++++
 .../selftests/kvm/lib/aarch64/processor.c      | 18 +++++++++---------
 tools/testing/selftests/kvm/lib/kvm_util.c     |  6 ++++++
 3 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h b/tools/testing/selftests/kvm/include/kvm_util_base.h
index e42a09cd24a0..eec0e4898efe 100644
--- a/tools/testing/selftests/kvm/include/kvm_util_base.h
+++ b/tools/testing/selftests/kvm/include/kvm_util_base.h
@@ -838,4 +838,9 @@ static inline int __vm_disable_nx_huge_pages(struct kvm_vm *vm)
 	return __vm_enable_cap(vm, KVM_CAP_VM_DISABLE_NX_HUGE_PAGES, 0);
 }
 
+/*
+ * API to execute architecture specific setup before executing main().
+ */
+void kvm_selftest_arch_init(void);
+
 #endif /* SELFTEST_KVM_UTIL_BASE_H */
diff --git a/tools/testing/selftests/kvm/lib/aarch64/processor.c b/tools/testing/selftests/kvm/lib/aarch64/processor.c
index 6f5551368944..0de4aabc0c76 100644
--- a/tools/testing/selftests/kvm/lib/aarch64/processor.c
+++ b/tools/testing/selftests/kvm/lib/aarch64/processor.c
@@ -495,15 +495,6 @@ void aarch64_get_supported_page_sizes(uint32_t ipa,
 	close(kvm_fd);
 }
 
-/*
- * arm64 doesn't have a true default mode, so start by computing the
- * available IPA space and page sizes early.
- */
-void __attribute__((constructor)) init_guest_modes(void)
-{
-       guest_modes_append_default();
-}
-
 void smccc_hvc(uint32_t function_id, uint64_t arg0, uint64_t arg1,
 	       uint64_t arg2, uint64_t arg3, uint64_t arg4, uint64_t arg5,
 	       uint64_t arg6, struct arm_smccc_res *res)
@@ -528,3 +519,12 @@ void smccc_hvc(uint32_t function_id, uint64_t arg0, uint64_t arg1,
 		       [arg4] "r"(arg4), [arg5] "r"(arg5), [arg6] "r"(arg6)
 		     : "x0", "x1", "x2", "x3", "x4", "x5", "x6", "x7");
 }
+
+void kvm_selftest_arch_init(void)
+{
+	/*
+	 * arm64 doesn't have a true default mode, so start by computing the
+	 * available IPA space and page sizes early.
+	 */
+	guest_modes_append_default();
+}
diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index 37d7d144c74e..deb4c731b9fa 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -2022,8 +2022,14 @@ void __vm_get_stat(struct kvm_vm *vm, const char *stat_name, uint64_t *data,
 	}
 }
 
+__weak void kvm_selftest_arch_init(void)
+{
+}
+
 void __attribute((constructor)) kvm_selftest_init(void)
 {
 	/* Tell stdout not to buffer its content. */
 	setbuf(stdout, NULL);
+
+	kvm_selftest_arch_init();
 }
-- 
2.38.1.431.g37b22c650d-goog

On Tue, Nov 15, 2022, Vishal Annapurve wrote:
> Introduce arch specific API: kvm_selftest_arch_init to allow each arch to
> handle initialization before running any selftest logic.
> 
> Suggested-by: Sean Christopherson <seanjc@google.com>
> Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
> Reviewed-by: Peter Gonda <pgonda@google.com>
> Signed-off-by: Vishal Annapurve <vannapurve@google.com>
> ---
>  .../selftests/kvm/include/kvm_util_base.h      |  5 +++++
>  .../selftests/kvm/lib/aarch64/processor.c      | 18 +++++++++---------
>  tools/testing/selftests/kvm/lib/kvm_util.c     |  6 ++++++
>  3 files changed, 20 insertions(+), 9 deletions(-)
> 
> diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h b/tools/testing/selftests/kvm/include/kvm_util_base.h
> index e42a09cd24a0..eec0e4898efe 100644
> --- a/tools/testing/selftests/kvm/include/kvm_util_base.h
> +++ b/tools/testing/selftests/kvm/include/kvm_util_base.h
> @@ -838,4 +838,9 @@ static inline int __vm_disable_nx_huge_pages(struct kvm_vm *vm)
>  	return __vm_enable_cap(vm, KVM_CAP_VM_DISABLE_NX_HUGE_PAGES, 0);
>  }
>  
> +/*
> + * API to execute architecture specific setup before executing main().
> + */

I find the "API" blurb to be somewhat confusing.  When I think of APIs, I think
of functions that are provided by a library that are called by users of the
library.

An example might also help readers understand what types of setup can/should be
done with this hook.

Maybe something like this?

/*
 * Arch hook that is invoked via a constructor, i.e. before exeucting main(),
 * to allow for arch-specific setup that is common to all tests, e.g. computing
 * the default guest "mode".
 */

On Wed, Nov 16, 2022 at 9:46 AM Sean Christopherson <seanjc@google.com> wrote:
>
> On Tue, Nov 15, 2022, Vishal Annapurve wrote:
> > Introduce arch specific API: kvm_selftest_arch_init to allow each arch to
> > handle initialization before running any selftest logic.
> >
> > Suggested-by: Sean Christopherson <seanjc@google.com>
> > Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
> > Reviewed-by: Peter Gonda <pgonda@google.com>
> > Signed-off-by: Vishal Annapurve <vannapurve@google.com>
> > ---
> >  .../selftests/kvm/include/kvm_util_base.h      |  5 +++++
> >  .../selftests/kvm/lib/aarch64/processor.c      | 18 +++++++++---------
> >  tools/testing/selftests/kvm/lib/kvm_util.c     |  6 ++++++
> >  3 files changed, 20 insertions(+), 9 deletions(-)
> >
> > diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h b/tools/testing/selftests/kvm/include/kvm_util_base.h
> > index e42a09cd24a0..eec0e4898efe 100644
> > --- a/tools/testing/selftests/kvm/include/kvm_util_base.h
> > +++ b/tools/testing/selftests/kvm/include/kvm_util_base.h
> > @@ -838,4 +838,9 @@ static inline int __vm_disable_nx_huge_pages(struct kvm_vm *vm)
> >       return __vm_enable_cap(vm, KVM_CAP_VM_DISABLE_NX_HUGE_PAGES, 0);
> >  }
> >
> > +/*
> > + * API to execute architecture specific setup before executing main().
> > + */
>
> I find the "API" blurb to be somewhat confusing.  When I think of APIs, I think
> of functions that are provided by a library that are called by users of the
> library.
>
> An example might also help readers understand what types of setup can/should be
> done with this hook.
>
> Maybe something like this?
>
> /*
>  * Arch hook that is invoked via a constructor, i.e. before exeucting main(),
>  * to allow for arch-specific setup that is common to all tests, e.g. computing
>  * the default guest "mode".
>  */

Ack, that looks better.