[PATCH v2] vfio: selftests: only build tests on arm64 and x86_64

[PATCH v2] vfio: selftests: only build tests on arm64 and x86_64

[Ted Logan]

Only build vfio self-tests on arm64 and x86_64; these are the only
architectures where the vfio self-tests are run. Addresses compiler
warnings for format and conversions on i386.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202601211830.aBEjmEFD-lkp@intel.com/
Signed-off-by: Ted Logan <tedlogan@fb.com>
---
Do not build vfio self-tests for 32-bit architectures, where they're
untested and unmaintained. Only build these tests for arm64 and x86_64,
where they're regularly tested.

Compiler warning fixed by patch:

   In file included from tools/testing/selftests/vfio/lib/include/libvfio.h:6:
   tools/testing/selftests/vfio/lib/include/libvfio/iommu.h:49:2: warning: format specifies type 'unsigned long' but the argument has type 'u64' (aka 'unsigned long long') [-Wformat]
      49 |         VFIO_ASSERT_EQ(__iommu_unmap(iommu, region, NULL), 0);
         |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   tools/testing/selftests/vfio/lib/include/libvfio/assert.h:32:37: note: expanded from macro 'VFIO_ASSERT_EQ'
      32 | #define VFIO_ASSERT_EQ(_a, _b, ...) VFIO_ASSERT_OP(_a, _b, ==, ##__VA_ARGS__)
         |                                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   tools/testing/selftests/vfio/lib/include/libvfio/assert.h:27:22: note: expanded from macro 'VFIO_ASSERT_OP'
      26 |         fprintf(stderr, "  Observed: %#lx %s %#lx\n",                           \
         |                                              ~~~~
      27 |                         (u64)__lhs, #_op, (u64)__rhs);                          \
         |                                           ^~~~~~~~~~
---
Changes in v2:
- Add white space around arch checks
- Clean up uname command
- Link to v1: https://lore.kernel.org/r/20260130-vfio-selftest-only-64bit-v1-1-d89ac0944c01@fb.com
---
 tools/testing/selftests/vfio/Makefile | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/tools/testing/selftests/vfio/Makefile b/tools/testing/selftests/vfio/Makefile
index ead27892ab65..8e90e409e91d 100644
--- a/tools/testing/selftests/vfio/Makefile
+++ b/tools/testing/selftests/vfio/Makefile
@@ -1,3 +1,10 @@
+ARCH ?= $(shell uname -m)
+
+ifeq (,$(filter $(ARCH),arm64 x86_64))
+# Do nothing on unsupported architectures
+include ../lib.mk
+else
+
 CFLAGS = $(KHDR_INCLUDES)
 TEST_GEN_PROGS += vfio_dma_mapping_test
 TEST_GEN_PROGS += vfio_dma_mapping_mmio_test
@@ -28,3 +35,5 @@ TEST_DEP_FILES = $(patsubst %.o, %.d, $(TEST_GEN_PROGS_O) $(LIBVFIO_O))
 -include $(TEST_DEP_FILES)
 
 EXTRA_CLEAN += $(TEST_GEN_PROGS_O) $(TEST_DEP_FILES)
+
+endif

---
base-commit: c3cbc276c2a33b04fc78a86cdb2ddce094cb3614
change-id: 20260130-vfio-selftest-only-64bit-422518bdeba7

Best regards,
-- 
Ted Logan <tedlogan@fb.com>

Re: [PATCH v2] vfio: selftests: only build tests on arm64 and x86_64

[David Matlack]

On Mon, Feb 2, 2026 at 5:24 PM Ted Logan <tedlogan@fb.com> wrote:
>
> Only build vfio self-tests on arm64 and x86_64; these are the only
> architectures where the vfio self-tests are run. Addresses compiler
> warnings for format and conversions on i386.
>
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202601211830.aBEjmEFD-lkp@intel.com/
> Signed-off-by: Ted Logan <tedlogan@fb.com>

Reviewed-by: David Matlack <dmatlack@google.com>

Re: [PATCH v2] vfio: selftests: only build tests on arm64 and x86_64

[Alex Williamson]

On Mon, 2 Feb 2026 17:23:53 -0800
Ted Logan <tedlogan@fb.com> wrote:

> Only build vfio self-tests on arm64 and x86_64; these are the only
> architectures where the vfio self-tests are run. Addresses compiler
> warnings for format and conversions on i386.
> 
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202601211830.aBEjmEFD-lkp@intel.com/
> Signed-off-by: Ted Logan <tedlogan@fb.com>
> ---
> Do not build vfio self-tests for 32-bit architectures, where they're
> untested and unmaintained. Only build these tests for arm64 and x86_64,
> where they're regularly tested.
> 
> Compiler warning fixed by patch:
> 
>    In file included from tools/testing/selftests/vfio/lib/include/libvfio.h:6:
>    tools/testing/selftests/vfio/lib/include/libvfio/iommu.h:49:2: warning: format specifies type 'unsigned long' but the argument has type 'u64' (aka 'unsigned long long') [-Wformat]
>       49 |         VFIO_ASSERT_EQ(__iommu_unmap(iommu, region, NULL), 0);
>          |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>    tools/testing/selftests/vfio/lib/include/libvfio/assert.h:32:37: note: expanded from macro 'VFIO_ASSERT_EQ'
>       32 | #define VFIO_ASSERT_EQ(_a, _b, ...) VFIO_ASSERT_OP(_a, _b, ==, ##__VA_ARGS__)
>          |                                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>    tools/testing/selftests/vfio/lib/include/libvfio/assert.h:27:22: note: expanded from macro 'VFIO_ASSERT_OP'
>       26 |         fprintf(stderr, "  Observed: %#lx %s %#lx\n",                           \
>          |                                              ~~~~
>       27 |                         (u64)__lhs, #_op, (u64)__rhs);                          \
>          |                                           ^~~~~~~~~~
> ---
> Changes in v2:
> - Add white space around arch checks
> - Clean up uname command
> - Link to v1: https://lore.kernel.org/r/20260130-vfio-selftest-only-64bit-v1-1-d89ac0944c01@fb.com
> ---
>  tools/testing/selftests/vfio/Makefile | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/tools/testing/selftests/vfio/Makefile b/tools/testing/selftests/vfio/Makefile
> index ead27892ab65..8e90e409e91d 100644
> --- a/tools/testing/selftests/vfio/Makefile
> +++ b/tools/testing/selftests/vfio/Makefile
> @@ -1,3 +1,10 @@
> +ARCH ?= $(shell uname -m)
> +
> +ifeq (,$(filter $(ARCH),arm64 x86_64))
> +# Do nothing on unsupported architectures
> +include ../lib.mk
> +else
> +
>  CFLAGS = $(KHDR_INCLUDES)
>  TEST_GEN_PROGS += vfio_dma_mapping_test
>  TEST_GEN_PROGS += vfio_dma_mapping_mmio_test
> @@ -28,3 +35,5 @@ TEST_DEP_FILES = $(patsubst %.o, %.d, $(TEST_GEN_PROGS_O) $(LIBVFIO_O))
>  -include $(TEST_DEP_FILES)
>  
>  EXTRA_CLEAN += $(TEST_GEN_PROGS_O) $(TEST_DEP_FILES)
> +
> +endif
> 
> ---
> base-commit: c3cbc276c2a33b04fc78a86cdb2ddce094cb3614
> change-id: 20260130-vfio-selftest-only-64bit-422518bdeba7
> 
> Best regards,

Applied to vfio next branch for v7.0/6.20.  Thanks,

Alex

Re: [PATCH v2] vfio: selftests: only build tests on arm64 and x86_64

[Matt Evans]

Hi Ted,

On 03/02/2026 01:23, Ted Logan wrote:
> Only build vfio self-tests on arm64 and x86_64; these are the only
> architectures where the vfio self-tests are run. Addresses compiler
> warnings for format and conversions on i386.
> 
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202601211830.aBEjmEFD-lkp@intel.com/
> Signed-off-by: Ted Logan <tedlogan@fb.com>
> ---
> Do not build vfio self-tests for 32-bit architectures, where they're
> untested and unmaintained. Only build these tests for arm64 and x86_64,
> where they're regularly tested.
> 
> Compiler warning fixed by patch:
> 
>    In file included from tools/testing/selftests/vfio/lib/include/libvfio.h:6:
>    tools/testing/selftests/vfio/lib/include/libvfio/iommu.h:49:2: warning: format specifies type 'unsigned long' but the argument has type 'u64' (aka 'unsigned long long') [-Wformat]
>       49 |         VFIO_ASSERT_EQ(__iommu_unmap(iommu, region, NULL), 0);
>          |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>    tools/testing/selftests/vfio/lib/include/libvfio/assert.h:32:37: note: expanded from macro 'VFIO_ASSERT_EQ'
>       32 | #define VFIO_ASSERT_EQ(_a, _b, ...) VFIO_ASSERT_OP(_a, _b, ==, ##__VA_ARGS__)
>          |                                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>    tools/testing/selftests/vfio/lib/include/libvfio/assert.h:27:22: note: expanded from macro 'VFIO_ASSERT_OP'
>       26 |         fprintf(stderr, "  Observed: %#lx %s %#lx\n",                           \
>          |                                              ~~~~
>       27 |                         (u64)__lhs, #_op, (u64)__rhs);                          \
>          |                                           ^~~~~~~~~~
> ---
> Changes in v2:
> - Add white space around arch checks
> - Clean up uname command
> - Link to v1: https://lore.kernel.org/r/20260130-vfio-selftest-only-64bit-v1-1-d89ac0944c01@fb.com
> ---
>  tools/testing/selftests/vfio/Makefile | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/tools/testing/selftests/vfio/Makefile b/tools/testing/selftests/vfio/Makefile
> index ead27892ab65..8e90e409e91d 100644
> --- a/tools/testing/selftests/vfio/Makefile
> +++ b/tools/testing/selftests/vfio/Makefile
> @@ -1,3 +1,10 @@
> +ARCH ?= $(shell uname -m)
> +
> +ifeq (,$(filter $(ARCH),arm64 x86_64))

This fails to build (i.e. elides the build) on my local arm64 machine,
because uname -m returns 'aarch64', not 'arm64'.

Are you seeing an arm64 (Linux! [1]) machine where uname -m is 'arm64'...?

This patch needs some translation, of the sort in
 tools/testing/selftests/mm/Makefile:15


-Matt

[1] Note on macOS/M-Mac, uname -m is indeed 'arm64', but not so on Linux.

> +# Do nothing on unsupported architectures
> +include ../lib.mk
> +else
> +
>  CFLAGS = $(KHDR_INCLUDES)
>  TEST_GEN_PROGS += vfio_dma_mapping_test
>  TEST_GEN_PROGS += vfio_dma_mapping_mmio_test
> @@ -28,3 +35,5 @@ TEST_DEP_FILES = $(patsubst %.o, %.d, $(TEST_GEN_PROGS_O) $(LIBVFIO_O))
>  -include $(TEST_DEP_FILES)
>  
>  EXTRA_CLEAN += $(TEST_GEN_PROGS_O) $(TEST_DEP_FILES)
> +
> +endif
> 
> ---
> base-commit: c3cbc276c2a33b04fc78a86cdb2ddce094cb3614
> change-id: 20260130-vfio-selftest-only-64bit-422518bdeba7
> 
> Best regards,

Re: [PATCH v2] vfio: selftests: only build tests on arm64 and x86_64

[Ted Logan]

On Tue, Mar 17, 2026 at 01:55:17PM +0000, Matt Evans wrote:
> On 03/02/2026 01:23, Ted Logan wrote:
> > diff --git a/tools/testing/selftests/vfio/Makefile b/tools/testing/selftests/vfio/Makefile
> > index ead27892ab65..8e90e409e91d 100644
> > --- a/tools/testing/selftests/vfio/Makefile
> > +++ b/tools/testing/selftests/vfio/Makefile
> > @@ -1,3 +1,10 @@
> > +ARCH ?= $(shell uname -m)
> > +
> > +ifeq (,$(filter $(ARCH),arm64 x86_64))
> 
> This fails to build (i.e. elides the build) on my local arm64 machine,
> because uname -m returns 'aarch64', not 'arm64'.
> 
> Are you seeing an arm64 (Linux! [1]) machine where uname -m is 'arm64'...?
> 
> This patch needs some translation, of the sort in
>  tools/testing/selftests/mm/Makefile:15
> 
> 
> -Matt
> 
> [1] Note on macOS/M-Mac, uname -m is indeed 'arm64', but not so on Linux.

I didn't have an aarch64 system handy to test when I sent my first
patch, so I went with David's comment in an earlier thread that x86_64
and arm64 are supported. I did just fire up a Linux VM on my Mac and I
see it does indeed report the arch as aarch64, and that it builds the
self-tests without warnings. I'll mail a patch to translate the
architecture as you suggest.

- Ted

Re: [PATCH v2] vfio: selftests: only build tests on arm64 and x86_64

[Jason Gunthorpe]

On Tue, Mar 17, 2026 at 01:55:17PM +0000, Matt Evans wrote:
> Hi Ted,
> 
> On 03/02/2026 01:23, Ted Logan wrote:
> > Only build vfio self-tests on arm64 and x86_64; these are the only
> > architectures where the vfio self-tests are run. Addresses compiler
> > warnings for format and conversions on i386.
> > 
> > Reported-by: kernel test robot <lkp@intel.com>
> > Closes: https://lore.kernel.org/oe-kbuild-all/202601211830.aBEjmEFD-lkp@intel.com/
> > Signed-off-by: Ted Logan <tedlogan@fb.com>
> > ---
> > Do not build vfio self-tests for 32-bit architectures, where they're
> > untested and unmaintained. Only build these tests for arm64 and x86_64,
> > where they're regularly tested.
> > 
> > Compiler warning fixed by patch:
> > 
> >    In file included from tools/testing/selftests/vfio/lib/include/libvfio.h:6:
> >    tools/testing/selftests/vfio/lib/include/libvfio/iommu.h:49:2: warning: format specifies type 'unsigned long' but the argument has type 'u64' (aka 'unsigned long long') [-Wformat]
> >       49 |         VFIO_ASSERT_EQ(__iommu_unmap(iommu, region, NULL), 0);
> >          |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >    tools/testing/selftests/vfio/lib/include/libvfio/assert.h:32:37: note: expanded from macro 'VFIO_ASSERT_EQ'
> >       32 | #define VFIO_ASSERT_EQ(_a, _b, ...) VFIO_ASSERT_OP(_a, _b, ==, ##__VA_ARGS__)
> >          |                                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >    tools/testing/selftests/vfio/lib/include/libvfio/assert.h:27:22: note: expanded from macro 'VFIO_ASSERT_OP'
> >       26 |         fprintf(stderr, "  Observed: %#lx %s %#lx\n",                           \
> >          |                                              ~~~~
> >       27 |                         (u64)__lhs, #_op, (u64)__rhs);                          \
> >          |                                           ^~~~~~~~~~
> > ---
> > Changes in v2:
> > - Add white space around arch checks
> > - Clean up uname command
> > - Link to v1: https://lore.kernel.org/r/20260130-vfio-selftest-only-64bit-v1-1-d89ac0944c01@fb.com
> > ---
> >  tools/testing/selftests/vfio/Makefile | 9 +++++++++
> >  1 file changed, 9 insertions(+)
> > 
> > diff --git a/tools/testing/selftests/vfio/Makefile b/tools/testing/selftests/vfio/Makefile
> > index ead27892ab65..8e90e409e91d 100644
> > --- a/tools/testing/selftests/vfio/Makefile
> > +++ b/tools/testing/selftests/vfio/Makefile
> > @@ -1,3 +1,10 @@
> > +ARCH ?= $(shell uname -m)
> > +
> > +ifeq (,$(filter $(ARCH),arm64 x86_64))
> 
> This fails to build (i.e. elides the build) on my local arm64 machine,
> because uname -m returns 'aarch64', not 'arm64'.

I have the same issue on x86! The kernel uses x86 is the ARCH when you
run it straight from the top level make

make[4]: Entering directory '/home/jgg/oss/wip/mlx5st/tools/testing/selftests/vfio'
Makefile:1: "Saw ARCH=x86"

Even though this is a 64 bit build.

Jason

Re: [PATCH v2] vfio: selftests: only build tests on arm64 and x86_64

[Sean Christopherson]

On Mon, Apr 27, 2026, Jason Gunthorpe wrote:
> On Tue, Mar 17, 2026 at 01:55:17PM +0000, Matt Evans wrote:
> > Hi Ted,
> > 
> > On 03/02/2026 01:23, Ted Logan wrote:
> > > Only build vfio self-tests on arm64 and x86_64; these are the only
> > > architectures where the vfio self-tests are run. Addresses compiler
> > > warnings for format and conversions on i386.
> > > 
> > > Reported-by: kernel test robot <lkp@intel.com>
> > > Closes: https://lore.kernel.org/oe-kbuild-all/202601211830.aBEjmEFD-lkp@intel.com/
> > > Signed-off-by: Ted Logan <tedlogan@fb.com>
> > > ---
> > > Do not build vfio self-tests for 32-bit architectures, where they're
> > > untested and unmaintained. Only build these tests for arm64 and x86_64,
> > > where they're regularly tested.
> > > 
> > > Compiler warning fixed by patch:
> > > 
> > >    In file included from tools/testing/selftests/vfio/lib/include/libvfio.h:6:
> > >    tools/testing/selftests/vfio/lib/include/libvfio/iommu.h:49:2: warning: format specifies type 'unsigned long' but the argument has type 'u64' (aka 'unsigned long long') [-Wformat]
> > >       49 |         VFIO_ASSERT_EQ(__iommu_unmap(iommu, region, NULL), 0);
> > >          |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > >    tools/testing/selftests/vfio/lib/include/libvfio/assert.h:32:37: note: expanded from macro 'VFIO_ASSERT_EQ'
> > >       32 | #define VFIO_ASSERT_EQ(_a, _b, ...) VFIO_ASSERT_OP(_a, _b, ==, ##__VA_ARGS__)
> > >          |                                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > >    tools/testing/selftests/vfio/lib/include/libvfio/assert.h:27:22: note: expanded from macro 'VFIO_ASSERT_OP'
> > >       26 |         fprintf(stderr, "  Observed: %#lx %s %#lx\n",                           \
> > >          |                                              ~~~~
> > >       27 |                         (u64)__lhs, #_op, (u64)__rhs);                          \
> > >          |                                           ^~~~~~~~~~
> > > ---
> > > Changes in v2:
> > > - Add white space around arch checks
> > > - Clean up uname command
> > > - Link to v1: https://lore.kernel.org/r/20260130-vfio-selftest-only-64bit-v1-1-d89ac0944c01@fb.com
> > > ---
> > >  tools/testing/selftests/vfio/Makefile | 9 +++++++++
> > >  1 file changed, 9 insertions(+)
> > > 
> > > diff --git a/tools/testing/selftests/vfio/Makefile b/tools/testing/selftests/vfio/Makefile
> > > index ead27892ab65..8e90e409e91d 100644
> > > --- a/tools/testing/selftests/vfio/Makefile
> > > +++ b/tools/testing/selftests/vfio/Makefile
> > > @@ -1,3 +1,10 @@
> > > +ARCH ?= $(shell uname -m)
> > > +
> > > +ifeq (,$(filter $(ARCH),arm64 x86_64))
> > 
> > This fails to build (i.e. elides the build) on my local arm64 machine,
> > because uname -m returns 'aarch64', not 'arm64'.
> 
> I have the same issue on x86! The kernel uses x86 is the ARCH when you
> run it straight from the top level make
> 
> make[4]: Entering directory '/home/jgg/oss/wip/mlx5st/tools/testing/selftests/vfio'
> Makefile:1: "Saw ARCH=x86"
> 
> Even though this is a 64 bit build.

Heh, it's much funnier when it's happening to someone else.  :-)

KVM selftests went through these exact pains.  I'm pretty sure these are the
relevant commits (the empty targets one may or may not apply to VFIO).

9af04539d474dda4984ff4909d4568e6123c8cba KVM: selftests: Override ARCH for x86_64 instead of using ARCH_DIR
67730e6c53d70fb31618230f81c4acee9f72eaa3 KVM: selftests: Use canonical $(ARCH) paths for KVM selftests directories
43fbd8cd389faa9760c5152b1c58e893c812953b KVM: selftests: Provide empty 'all' and 'clean' targets for unsupported ARCHs

Re: [PATCH v2] vfio: selftests: only build tests on arm64 and x86_64

[David Matlack]

On 2026-04-27 06:55 PM, Sean Christopherson wrote:
> On Mon, Apr 27, 2026, Jason Gunthorpe wrote:
> > On Tue, Mar 17, 2026 at 01:55:17PM +0000, Matt Evans wrote:
> > > Hi Ted,
> > > 
> > > On 03/02/2026 01:23, Ted Logan wrote:
> > > > Only build vfio self-tests on arm64 and x86_64; these are the only
> > > > architectures where the vfio self-tests are run. Addresses compiler
> > > > warnings for format and conversions on i386.
> > > > 
> > > > Reported-by: kernel test robot <lkp@intel.com>
> > > > Closes: https://lore.kernel.org/oe-kbuild-all/202601211830.aBEjmEFD-lkp@intel.com/
> > > > Signed-off-by: Ted Logan <tedlogan@fb.com>
> > > > ---
> > > > Do not build vfio self-tests for 32-bit architectures, where they're
> > > > untested and unmaintained. Only build these tests for arm64 and x86_64,
> > > > where they're regularly tested.
> > > > 
> > > > Compiler warning fixed by patch:
> > > > 
> > > >    In file included from tools/testing/selftests/vfio/lib/include/libvfio.h:6:
> > > >    tools/testing/selftests/vfio/lib/include/libvfio/iommu.h:49:2: warning: format specifies type 'unsigned long' but the argument has type 'u64' (aka 'unsigned long long') [-Wformat]
> > > >       49 |         VFIO_ASSERT_EQ(__iommu_unmap(iommu, region, NULL), 0);
> > > >          |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > > >    tools/testing/selftests/vfio/lib/include/libvfio/assert.h:32:37: note: expanded from macro 'VFIO_ASSERT_EQ'
> > > >       32 | #define VFIO_ASSERT_EQ(_a, _b, ...) VFIO_ASSERT_OP(_a, _b, ==, ##__VA_ARGS__)
> > > >          |                                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > > >    tools/testing/selftests/vfio/lib/include/libvfio/assert.h:27:22: note: expanded from macro 'VFIO_ASSERT_OP'
> > > >       26 |         fprintf(stderr, "  Observed: %#lx %s %#lx\n",                           \
> > > >          |                                              ~~~~
> > > >       27 |                         (u64)__lhs, #_op, (u64)__rhs);                          \
> > > >          |                                           ^~~~~~~~~~
> > > > ---
> > > > Changes in v2:
> > > > - Add white space around arch checks
> > > > - Clean up uname command
> > > > - Link to v1: https://lore.kernel.org/r/20260130-vfio-selftest-only-64bit-v1-1-d89ac0944c01@fb.com
> > > > ---
> > > >  tools/testing/selftests/vfio/Makefile | 9 +++++++++
> > > >  1 file changed, 9 insertions(+)
> > > > 
> > > > diff --git a/tools/testing/selftests/vfio/Makefile b/tools/testing/selftests/vfio/Makefile
> > > > index ead27892ab65..8e90e409e91d 100644
> > > > --- a/tools/testing/selftests/vfio/Makefile
> > > > +++ b/tools/testing/selftests/vfio/Makefile
> > > > @@ -1,3 +1,10 @@
> > > > +ARCH ?= $(shell uname -m)
> > > > +
> > > > +ifeq (,$(filter $(ARCH),arm64 x86_64))
> > > 
> > > This fails to build (i.e. elides the build) on my local arm64 machine,
> > > because uname -m returns 'aarch64', not 'arm64'.
> > 
> > I have the same issue on x86! The kernel uses x86 is the ARCH when you
> > run it straight from the top level make
> > 
> > make[4]: Entering directory '/home/jgg/oss/wip/mlx5st/tools/testing/selftests/vfio'
> > Makefile:1: "Saw ARCH=x86"
> > 
> > Even though this is a 64 bit build.
> 
> Heh, it's much funnier when it's happening to someone else.  :-)
> 
> KVM selftests went through these exact pains.  I'm pretty sure these are the
> relevant commits (the empty targets one may or may not apply to VFIO).
> 
> 9af04539d474dda4984ff4909d4568e6123c8cba KVM: selftests: Override ARCH for x86_64 instead of using ARCH_DIR
> 67730e6c53d70fb31618230f81c4acee9f72eaa3 KVM: selftests: Use canonical $(ARCH) paths for KVM selftests directories
> 43fbd8cd389faa9760c5152b1c58e893c812953b KVM: selftests: Provide empty 'all' and 'clean' targets for unsupported ARCHs

KVM selftests don't prevent 32-bit x86 builds though, which is part of what
we're trying to do here.

For example running...

  $ make -C tools/testing/selftests/kvm ARCH=x86 CC="gcc -m32"

...produces a lot of -Wformat errors that were also seeing in VFIO selftests
from the kernel test robot.

I think something like this would fix your issue Jason. I haven't tested it on
ARM yet:

diff --git a/tools/testing/selftests/vfio/Makefile b/tools/testing/selftests/vfio/Makefile
index 0684932d91bf..db71aef6bfb2 100644
--- a/tools/testing/selftests/vfio/Makefile
+++ b/tools/testing/selftests/vfio/Makefile
@@ -1,6 +1,11 @@
 ARCH ?= $(shell uname -m)

-ifeq (,$(filter $(ARCH),aarch64 arm64 x86_64))
+# VFIO selftests are currently only supported on 64-bit x86 and ARM.
+ifneq (,$(filter $(ARCH),x86 x86_64 aarch64 arm64))
+SUPPORTED_ARCH := $(shell echo __LP64__ | $(CC) $(CFLAGS) -E -x c - | tail -n 1)
+endif
+
+ifneq ($(SUPPORTED_ARCH),1)
 # Do nothing on unsupported architectures
 include ../lib.mk
 else

Re: [PATCH v2] vfio: selftests: only build tests on arm64 and x86_64

[Sean Christopherson]

On Tue, Apr 28, 2026, David Matlack wrote:
> On 2026-04-27 06:55 PM, Sean Christopherson wrote:
> > On Mon, Apr 27, 2026, Jason Gunthorpe wrote:
> > > Even though this is a 64 bit build.
> > 
> > Heh, it's much funnier when it's happening to someone else.  :-)
> > 
> > KVM selftests went through these exact pains.  I'm pretty sure these are the
> > relevant commits (the empty targets one may or may not apply to VFIO).
> > 
> > 9af04539d474dda4984ff4909d4568e6123c8cba KVM: selftests: Override ARCH for x86_64 instead of using ARCH_DIR
> > 67730e6c53d70fb31618230f81c4acee9f72eaa3 KVM: selftests: Use canonical $(ARCH) paths for KVM selftests directories
> > 43fbd8cd389faa9760c5152b1c58e893c812953b KVM: selftests: Provide empty 'all' and 'clean' targets for unsupported ARCHs
> 
> KVM selftests don't prevent 32-bit x86 builds though,

Yes they do?  x86 is an alias for x86_64 (or vice versa), and so the i386 target
gets binned into the empty target provided by tools/testing/selftests/kvm/Makefile.
And KVM selftests most definitely don't play nice with 32-bit.

> which is part of what we're trying to do here.
> 
> For example running...
> 
>   $ make -C tools/testing/selftests/kvm ARCH=x86 CC="gcc -m32"
> 
> ...produces a lot of -Wformat errors that were also seeing in VFIO selftests
> from the kernel test robot.

Uh, don't do that?  KVM selftests can't even get past the preprocessor with -m32.
Either the kernel test robot is trolling y'all, or there's something missing in
the VFIO configuration, because I'm not seeing any magic in KVM to guard against
the above.

Re: [PATCH v2] vfio: selftests: only build tests on arm64 and x86_64

[David Matlack]

On Tue, Apr 28, 2026 at 12:52 PM Sean Christopherson <seanjc@google.com> wrote:
>
> On Tue, Apr 28, 2026, David Matlack wrote:
> > On 2026-04-27 06:55 PM, Sean Christopherson wrote:
> > > On Mon, Apr 27, 2026, Jason Gunthorpe wrote:
> > > > Even though this is a 64 bit build.
> > >
> > > Heh, it's much funnier when it's happening to someone else.  :-)
> > >
> > > KVM selftests went through these exact pains.  I'm pretty sure these are the
> > > relevant commits (the empty targets one may or may not apply to VFIO).
> > >
> > > 9af04539d474dda4984ff4909d4568e6123c8cba KVM: selftests: Override ARCH for x86_64 instead of using ARCH_DIR
> > > 67730e6c53d70fb31618230f81c4acee9f72eaa3 KVM: selftests: Use canonical $(ARCH) paths for KVM selftests directories
> > > 43fbd8cd389faa9760c5152b1c58e893c812953b KVM: selftests: Provide empty 'all' and 'clean' targets for unsupported ARCHs
> >
> > KVM selftests don't prevent 32-bit x86 builds though,
>
> Yes they do?  x86 is an alias for x86_64 (or vice versa), and so the i386 target
> gets binned into the empty target provided by tools/testing/selftests/kvm/Makefile.
> And KVM selftests most definitely don't play nice with 32-bit.

Are you sure that x86 is an alias for x86_64? If it is then we don't
even need the __LP64__ stuff I posted.

But when I look at the top-level Makefile and imagine running make
without setting ARCH on the command line on a 32-bit x86 host, ARCH
will be set to SUBARCH, which will be x86.

Re: [PATCH v2] vfio: selftests: only build tests on arm64 and x86_64

[Sean Christopherson]

On Tue, Apr 28, 2026, David Matlack wrote:
> On Tue, Apr 28, 2026 at 12:52 PM Sean Christopherson <seanjc@google.com> wrote:
> >
> > On Tue, Apr 28, 2026, David Matlack wrote:
> > > On 2026-04-27 06:55 PM, Sean Christopherson wrote:
> > > > On Mon, Apr 27, 2026, Jason Gunthorpe wrote:
> > > > > Even though this is a 64 bit build.
> > > >
> > > > Heh, it's much funnier when it's happening to someone else.  :-)
> > > >
> > > > KVM selftests went through these exact pains.  I'm pretty sure these are the
> > > > relevant commits (the empty targets one may or may not apply to VFIO).
> > > >
> > > > 9af04539d474dda4984ff4909d4568e6123c8cba KVM: selftests: Override ARCH for x86_64 instead of using ARCH_DIR
> > > > 67730e6c53d70fb31618230f81c4acee9f72eaa3 KVM: selftests: Use canonical $(ARCH) paths for KVM selftests directories
> > > > 43fbd8cd389faa9760c5152b1c58e893c812953b KVM: selftests: Provide empty 'all' and 'clean' targets for unsupported ARCHs
> > >
> > > KVM selftests don't prevent 32-bit x86 builds though,
> >
> > Yes they do?  x86 is an alias for x86_64 (or vice versa), and so the i386 target
> > gets binned into the empty target provided by tools/testing/selftests/kvm/Makefile.
> > And KVM selftests most definitely don't play nice with 32-bit.
> 
> Are you sure that x86 is an alias for x86_64?

Well, I was quite sure :-)   But scripts/subarch.include disagrees:

  SUBARCH := $(shell uname -m | sed -e s/i.86/x86/ -e s/x86_64/x86/ \

as does attempting to build KVM selftests on a 32-bit host.

> If it is then we don't even need the __LP64__ stuff I posted.
> 
> But when I look at the top-level Makefile and imagine running make
> without setting ARCH on the command line on a 32-bit x86 host, ARCH
> will be set to SUBARCH, which will be x86.

Yep.  So the big question is, why doesn't anyone complain about KVM selftests not
building on 32-bit?  Because they most definitely don't build.

Re: [PATCH v2] vfio: selftests: only build tests on arm64 and x86_64

[David Matlack]

On Tue, Apr 28, 2026 at 3:03 PM Sean Christopherson <seanjc@google.com> wrote:
>
> On Tue, Apr 28, 2026, David Matlack wrote:
> > On Tue, Apr 28, 2026 at 12:52 PM Sean Christopherson <seanjc@google.com> wrote:
> > >
> > > On Tue, Apr 28, 2026, David Matlack wrote:
> > > > On 2026-04-27 06:55 PM, Sean Christopherson wrote:
> > > > > On Mon, Apr 27, 2026, Jason Gunthorpe wrote:
> > > > > > Even though this is a 64 bit build.
> > > > >
> > > > > Heh, it's much funnier when it's happening to someone else.  :-)
> > > > >
> > > > > KVM selftests went through these exact pains.  I'm pretty sure these are the
> > > > > relevant commits (the empty targets one may or may not apply to VFIO).
> > > > >
> > > > > 9af04539d474dda4984ff4909d4568e6123c8cba KVM: selftests: Override ARCH for x86_64 instead of using ARCH_DIR
> > > > > 67730e6c53d70fb31618230f81c4acee9f72eaa3 KVM: selftests: Use canonical $(ARCH) paths for KVM selftests directories
> > > > > 43fbd8cd389faa9760c5152b1c58e893c812953b KVM: selftests: Provide empty 'all' and 'clean' targets for unsupported ARCHs
> > > >
> > > > KVM selftests don't prevent 32-bit x86 builds though,
> > >
> > > Yes they do?  x86 is an alias for x86_64 (or vice versa), and so the i386 target
> > > gets binned into the empty target provided by tools/testing/selftests/kvm/Makefile.
> > > And KVM selftests most definitely don't play nice with 32-bit.
> >
> > Are you sure that x86 is an alias for x86_64?
>
> Well, I was quite sure :-)   But scripts/subarch.include disagrees:
>
>   SUBARCH := $(shell uname -m | sed -e s/i.86/x86/ -e s/x86_64/x86/ \
>
> as does attempting to build KVM selftests on a 32-bit host.

Yeah that's what I was seeing as well. With that cleared up I'll send
a fix for VFIO selftests to allow ARCH=x86 if __LP64__ is defined,
which will fix Jason's issue.

> > If it is then we don't even need the __LP64__ stuff I posted.
> >
> > But when I look at the top-level Makefile and imagine running make
> > without setting ARCH on the command line on a 32-bit x86 host, ARCH
> > will be set to SUBARCH, which will be x86.
>
> Yep.  So the big question is, why doesn't anyone complain about KVM selftests not
> building on 32-bit?  Because they most definitely don't build.

I guess no one's building on 32-bit hosts anymore? :)

Re: [PATCH v2] vfio: selftests: only build tests on arm64 and x86_64

[Jason Gunthorpe]

On Tue, Apr 28, 2026 at 03:53:01PM -0700, David Matlack wrote:
> > > If it is then we don't even need the __LP64__ stuff I posted.
> > >
> > > But when I look at the top-level Makefile and imagine running make
> > > without setting ARCH on the command line on a 32-bit x86 host, ARCH
> > > will be set to SUBARCH, which will be x86.
> >
> > Yep.  So the big question is, why doesn't anyone complain about KVM selftests not
> > building on 32-bit?  Because they most definitely don't build.
> 
> I guess no one's building on 32-bit hosts anymore? :)

Well, if that's the case and kvm is broken too, then just ignore it
and turn on vfio for x86 like kvm does?

No sense in just fixing it for VFIO..

<sigh wishes to have a better build system for userspace selftests>

Jason

Re: [PATCH v2] vfio: selftests: only build tests on arm64 and x86_64

[David Matlack]

On 2026-04-28 07:55 PM, Jason Gunthorpe wrote:
> On Tue, Apr 28, 2026 at 03:53:01PM -0700, David Matlack wrote:
> > > > If it is then we don't even need the __LP64__ stuff I posted.
> > > >
> > > > But when I look at the top-level Makefile and imagine running make
> > > > without setting ARCH on the command line on a 32-bit x86 host, ARCH
> > > > will be set to SUBARCH, which will be x86.
> > >
> > > Yep.  So the big question is, why doesn't anyone complain about KVM selftests not
> > > building on 32-bit?  Because they most definitely don't build.
> > 
> > I guess no one's building on 32-bit hosts anymore? :)
> 
> Well, if that's the case and kvm is broken too, then just ignore it
> and turn on vfio for x86 like kvm does?
> 
> No sense in just fixing it for VFIO..

That's fair... So something like this?

From: David Matlack <dmatlack@google.com>
Date: Tue, 28 Apr 2026 22:57:48 +0000
Subject: [PATCH] vfio: selftests: Allow builds when ARCH=x86

Allow builds when ARCH=x86 since the top-level Makefile can set ARCH=x86
even for 64-bit x86 builds. ARCH=x86 can also be set if the host is
32-bit x86, but based on the fact that KVM selftests allow ARCH=x86 but
also don't build for 32-bit x86, this isn't an issue in practice.

Reported-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: David Matlack <dmatlack@google.com>

diff --git a/tools/testing/selftests/vfio/Makefile b/tools/testing/selftests/vfio/Makefile
index 0684932d91bf..40165d087a0b 100644
--- a/tools/testing/selftests/vfio/Makefile
+++ b/tools/testing/selftests/vfio/Makefile
@@ -1,6 +1,6 @@
 ARCH ?= $(shell uname -m)

-ifeq (,$(filter $(ARCH),aarch64 arm64 x86_64))
+ifeq (,$(filter $(ARCH),aarch64 arm64 x86 x86_64))
 # Do nothing on unsupported architectures
 include ../lib.mk
 else
/usr/local/google/home/dmatlack/kernel/trees/vfio