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Reply-To: Sean Christopherson <seanjc@google.com>
Date:   Mon, 13 Jun 2022 16:19:40 +0000
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Subject: [PATCH 2/4] KVM: selftests: Call a dummy helper in VM/vCPU ioctls()
 to enforce type
From:   Sean Christopherson <seanjc@google.com>
To:     Paolo Bonzini <pbonzini@redhat.com>
Cc:     Andrew Jones <drjones@redhat.com>, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Replace the goofy static_assert on the size of the @vm/@vcpu parameters
with a call to a dummy helper, i.e. let the compiler naturally complain
about an incompatible type instead of homebrewing a poor replacement.

Reported-by: Andrew Jones <drjones@redhat.com>
Fixes: fcba483e8246 ("KVM: selftests: Sanity check input to ioctls() at build time")
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 .../selftests/kvm/include/kvm_util_base.h     | 57 ++++++++++---------
 1 file changed, 31 insertions(+), 26 deletions(-)

diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h b/tools/testing/selftests/kvm/include/kvm_util_base.h
index cdaea2383543..7ebfc8c7de17 100644
--- a/tools/testing/selftests/kvm/include/kvm_util_base.h
+++ b/tools/testing/selftests/kvm/include/kvm_util_base.h
@@ -186,50 +186,55 @@ static inline bool kvm_has_cap(long cap)
 	ioctl(fd, cmd, arg);							\
 })
 
-#define __kvm_ioctl(kvm_fd, cmd, arg)						\
+#define __kvm_ioctl(kvm_fd, cmd, arg)				\
 	kvm_do_ioctl(kvm_fd, cmd, arg)
 
 
-#define _kvm_ioctl(kvm_fd, cmd, name, arg)					\
-({										\
-	int ret = __kvm_ioctl(kvm_fd, cmd, arg);				\
-										\
-	TEST_ASSERT(!ret, __KVM_IOCTL_ERROR(name, ret));			\
+#define _kvm_ioctl(kvm_fd, cmd, name, arg)			\
+({								\
+	int ret = __kvm_ioctl(kvm_fd, cmd, arg);		\
+								\
+	TEST_ASSERT(!ret, __KVM_IOCTL_ERROR(name, ret));	\
 })
 
 #define kvm_ioctl(kvm_fd, cmd, arg) \
 	_kvm_ioctl(kvm_fd, cmd, #cmd, arg)
 
-#define __vm_ioctl(vm, cmd, arg)						\
-({										\
-	static_assert(sizeof(*(vm)) == sizeof(struct kvm_vm), "");		\
-	kvm_do_ioctl((vm)->fd, cmd, arg);					\
+static __always_inline void static_assert_is_vm(struct kvm_vm *vm) { }
+
+#define __vm_ioctl(vm, cmd, arg)				\
+({								\
+	static_assert_is_vm(vm);				\
+	kvm_do_ioctl((vm)->fd, cmd, arg);			\
 })
 
-#define _vm_ioctl(vm, cmd, name, arg)						\
-({										\
-	int ret = __vm_ioctl(vm, cmd, arg);					\
-										\
-	TEST_ASSERT(!ret, __KVM_IOCTL_ERROR(name, ret));			\
+#define _vm_ioctl(vm, cmd, name, arg)				\
+({								\
+	int ret = __vm_ioctl(vm, cmd, arg);			\
+								\
+	TEST_ASSERT(!ret, __KVM_IOCTL_ERROR(name, ret));	\
 })
 
-#define vm_ioctl(vm, cmd, arg)							\
+#define vm_ioctl(vm, cmd, arg)					\
 	_vm_ioctl(vm, cmd, #cmd, arg)
 
-#define __vcpu_ioctl(vcpu, cmd, arg)						\
-({										\
-	static_assert(sizeof(*(vcpu)) == sizeof(struct kvm_vcpu), "");		\
-	kvm_do_ioctl((vcpu)->fd, cmd, arg);					\
+
+static __always_inline void static_assert_is_vcpu(struct kvm_vcpu *vcpu) { }
+
+#define __vcpu_ioctl(vcpu, cmd, arg)				\
+({								\
+	static_assert_is_vcpu(vcpu);				\
+	kvm_do_ioctl((vcpu)->fd, cmd, arg);			\
 })
 
-#define _vcpu_ioctl(vcpu, cmd, name, arg)					\
-({										\
-	int ret = __vcpu_ioctl(vcpu, cmd, arg);					\
-										\
-	TEST_ASSERT(!ret, __KVM_IOCTL_ERROR(name, ret));			\
+#define _vcpu_ioctl(vcpu, cmd, name, arg)			\
+({								\
+	int ret = __vcpu_ioctl(vcpu, cmd, arg);			\
+								\
+	TEST_ASSERT(!ret, __KVM_IOCTL_ERROR(name, ret));	\
 })
 
-#define vcpu_ioctl(vcpu, cmd, arg)						\
+#define vcpu_ioctl(vcpu, cmd, arg)				\
 	_vcpu_ioctl(vcpu, cmd, #cmd, arg)
 
 /*
-- 
2.36.1.476.g0c4daa206d-goog