[PATCH rc] kvm: Prevent compiling virt/kvm/vfio.c unless VFIO is selected

[Jason Gunthorpe]

There are a bunch of reported randconfig failures now because of this,
something like:

>> arch/powerpc/kvm/../../../virt/kvm/vfio.c:89:7: warning: attribute declaration must precede definition [-Wignored-attributes]
           fn = symbol_get(vfio_file_iommu_group);
                ^
   include/linux/module.h:805:60: note: expanded from macro 'symbol_get'
   #define symbol_get(x) ({ extern typeof(x) x __attribute__((weak,visibility("hidden"))); &(x); })

It happens because the arch forces KVM_VFIO without knowing if VFIO is
even enabled.

Split the kconfig so the arch selects the usual HAVE_KVM_ARCH_VFIO and
then KVM_VFIO is only enabled if the arch wants it and VFIO is turned on.

Reported-by: kernel test robot <lkp at intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202308251949.5IiaV0sz-lkp@intel.com/
Closes: https://lore.kernel.org/oe-kbuild-all/202309030741.82aLACDG-lkp@intel.com/
Closes: https://lore.kernel.org/oe-kbuild-all/202309110914.QLH0LU6L-lkp@intel.com/
Cc: Nick Desaulniers <ndesaulniers at google.com>
Fixes: c1cce6d079b8 ("vfio: Compile vfio_group infrastructure optionally")
Signed-off-by: Jason Gunthorpe <jgg at nvidia.com>
---
 arch/arm64/kvm/Kconfig   | 2 +-
 arch/powerpc/kvm/Kconfig | 2 +-
 arch/s390/kvm/Kconfig    | 2 +-
 arch/x86/kvm/Kconfig     | 2 +-
 virt/kvm/Kconfig         | 7 ++++++-
 5 files changed, 10 insertions(+), 5 deletions(-)

Sean's large series will also address this:

https://lore.kernel.org/kvm/20230916003118.2540661-7-seanjc@google.com/

I don't know if it is sever enough to fix in the rc cycle, but here is the
patch.

diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
index 83c1e09be42e5b..7c43eaea51ce05 100644
--- a/arch/arm64/kvm/Kconfig
+++ b/arch/arm64/kvm/Kconfig
@@ -28,7 +28,7 @@ menuconfig KVM
 	select KVM_MMIO
 	select KVM_GENERIC_DIRTYLOG_READ_PROTECT
 	select KVM_XFER_TO_GUEST_WORK
-	select KVM_VFIO
+	select HAVE_KVM_ARCH_VFIO
 	select HAVE_KVM_EVENTFD
 	select HAVE_KVM_IRQFD
 	select HAVE_KVM_DIRTY_RING_ACQ_REL
diff --git a/arch/powerpc/kvm/Kconfig b/arch/powerpc/kvm/Kconfig
index 902611954200df..b64824e4cbc1eb 100644
--- a/arch/powerpc/kvm/Kconfig
+++ b/arch/powerpc/kvm/Kconfig
@@ -22,7 +22,7 @@ config KVM
 	select PREEMPT_NOTIFIERS
 	select HAVE_KVM_EVENTFD
 	select HAVE_KVM_VCPU_ASYNC_IOCTL
-	select KVM_VFIO
+	select HAVE_KVM_ARCH_VFIO
 	select IRQ_BYPASS_MANAGER
 	select HAVE_KVM_IRQ_BYPASS
 	select INTERVAL_TREE
diff --git a/arch/s390/kvm/Kconfig b/arch/s390/kvm/Kconfig
index 45fdf2a9b2e326..d206ad3a777d5d 100644
--- a/arch/s390/kvm/Kconfig
+++ b/arch/s390/kvm/Kconfig
@@ -31,7 +31,7 @@ config KVM
 	select HAVE_KVM_IRQ_ROUTING
 	select HAVE_KVM_INVALID_WAKEUPS
 	select HAVE_KVM_NO_POLL
-	select KVM_VFIO
+	select HAVE_KVM_ARCH_VFIO
 	select INTERVAL_TREE
 	select MMU_NOTIFIER
 	help
diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
index ed90f148140dfe..8e70e693f90e30 100644
--- a/arch/x86/kvm/Kconfig
+++ b/arch/x86/kvm/Kconfig
@@ -45,7 +45,7 @@ config KVM
 	select HAVE_KVM_NO_POLL
 	select KVM_XFER_TO_GUEST_WORK
 	select KVM_GENERIC_DIRTYLOG_READ_PROTECT
-	select KVM_VFIO
+	select HAVE_KVM_ARCH_VFIO
 	select INTERVAL_TREE
 	select HAVE_KVM_PM_NOTIFIER if PM
 	select KVM_GENERIC_HARDWARE_ENABLING
diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig
index 484d0873061ca5..0bf34809e1bbfe 100644
--- a/virt/kvm/Kconfig
+++ b/virt/kvm/Kconfig
@@ -59,9 +59,14 @@ config HAVE_KVM_MSI
 config HAVE_KVM_CPU_RELAX_INTERCEPT
        bool
 
-config KVM_VFIO
+config HAVE_KVM_ARCH_VFIO
        bool
 
+config KVM_VFIO
+       def_bool y
+       depends on HAVE_KVM_ARCH_VFIO
+       depends on VFIO
+
 config HAVE_KVM_INVALID_WAKEUPS
        bool
 

base-commit: 0bb80ecc33a8fb5a682236443c1e740d5c917d1d
-- 
2.42.0