Re: [PATCH 01/13] HACK: Ensure __NR_userfaultfd is defined

[Paolo Bonzini <pbonzini@xxxxxxxxxx>]

On 14/02/20 15:59, Andrew Jones wrote:
> Without this hack kvm/queue kvm selftests don't compile for x86_64.
> ---
>  tools/testing/selftests/kvm/demand_paging_test.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c
> index df1fc38b4df1..ec8860b70129 100644
> --- a/tools/testing/selftests/kvm/demand_paging_test.c
> +++ b/tools/testing/selftests/kvm/demand_paging_test.c
> @@ -20,6 +20,10 @@
>  #include <linux/bitops.h>
>  #include <linux/userfaultfd.h>
>  
> +#ifndef __NR_userfaultfd
> +#define __NR_userfaultfd 282
> +#endif
> +
>  #include "test_util.h"
>  #include "kvm_util.h"
>  #include "processor.h"
> 

This is because we're getting a limited version of
asm/unistd.h from tools/arch/x86/include/asm/unistd_64.h.
So:

------------ 8< ----------------
From: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Subject: [PATCH] fixup! KVM: selftests: Add demand paging content to the demand paging test

Without this, kvm selftests don't compile for x86_64 on old-enough
userspace.

diff --git a/tools/arch/x86/include/asm/unistd_64.h b/tools/arch/x86/include/asm/unistd_64.h
index cb52a3a8b8fc..4205ed4158bf 100644
--- a/tools/arch/x86/include/asm/unistd_64.h
+++ b/tools/arch/x86/include/asm/unistd_64.h
@@ -1,4 +1,7 @@
 /* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __NR_userfaultfd
+#define __NR_userfaultfd 282
+#endif
 #ifndef __NR_perf_event_open
 # define __NR_perf_event_open 298
 #endif
diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c
index df1fc38b4df1..dd6c5ee56201 100644
--- a/tools/testing/selftests/kvm/demand_paging_test.c
+++ b/tools/testing/selftests/kvm/demand_paging_test.c
@@ -13,6 +13,7 @@
 #include <stdlib.h>
 #include <sys/syscall.h>
 #include <unistd.h>
+#include <asm/unistd.h>
 #include <time.h>
 #include <poll.h>
 #include <pthread.h>
@@ -24,6 +25,8 @@
 #include "kvm_util.h"
 #include "processor.h"
 
+#ifdef __NR_userfaultfd
+
 /* The memory slot index demand page */
 #define TEST_MEM_SLOT_INDEX		1
 
@@ -678,3 +681,15 @@ int main(int argc, char *argv[])
 
 	return 0;
 }
+
+#else /* __NR_userfaultfd */
+
+#warning "missing __NR_userfaultfd definition"
+
+int main(void)
+{
+        printf("skip: Skipping userfaultfd test (missing __NR_userfaultfd)\n");
+        return KSFT_SKIP;
+}
+
+#endif /* __NR_userfaultfd */

Paolo