[RFC PATCH v2 18/37] KVM: selftests: Add helpers for calling ioctls on guest_memfd

[Ackerley Tng <ackerleytng@google.com>]

From: Sean Christopherson <seanjc@google.com>

Add helper functions to kvm_util.h to support calling ioctls, specifically
KVM_SET_MEMORY_ATTRIBUTES2, on a guest_memfd file descriptor.

Introduce gmem_ioctl() and __gmem_ioctl() macros, modeled after the
existing vm_ioctl() helpers, to provide a standard way to call ioctls
on a guest_memfd.

Add gmem_set_memory_attributes() and its derivatives (gmem_set_private(),
gmem_set_shared()) to set memory attributes on a guest_memfd region.
Also provide "__" variants that return the ioctl error code instead of
aborting the test. These helpers will be used by upcoming guest_memfd
tests.

To avoid code duplication, factor out the check for supported memory
attributes into a new macro, TEST_ASSERT_SUPPORTED_ATTRIBUTES, and use
it in both the existing vm_set_memory_attributes() and the new
gmem_set_memory_attributes() helpers.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 .../testing/selftests/kvm/include/kvm_util.h  | 89 +++++++++++++++++--
 1 file changed, 82 insertions(+), 7 deletions(-)

diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
index 872988197a5c..e767f9a99a7b 100644
--- a/tools/testing/selftests/kvm/include/kvm_util.h
+++ b/tools/testing/selftests/kvm/include/kvm_util.h
@@ -310,6 +310,16 @@ static inline bool kvm_has_cap(long cap)
 	TEST_ASSERT(!ret, __KVM_IOCTL_ERROR(#cmd, ret));	\
 })
 
+#define __gmem_ioctl(gmem_fd, cmd, arg)				\
+	kvm_do_ioctl(gmem_fd, cmd, arg)
+
+#define gmem_ioctl(gmem_fd, cmd, arg)				\
+({								\
+	int ret = __gmem_ioctl(gmem_fd, cmd, arg);		\
+								\
+	TEST_ASSERT(!ret, __KVM_IOCTL_ERROR(#cmd, ret));	\
+})
+
 static __always_inline void static_assert_is_vm(struct kvm_vm *vm) { }
 
 #define __vm_ioctl(vm, cmd, arg)				\
@@ -394,6 +404,14 @@ static inline void vm_enable_cap(struct kvm_vm *vm, uint32_t cap, uint64_t arg0)
 	vm_ioctl(vm, KVM_ENABLE_CAP, &enable_cap);
 }
 
+/*
+ * KVM_SET_MEMORY_ATTRIBUTES overwrites _all_ attributes.  These flows need
+ * significant enhancements to support multiple attributes.
+ */
+#define TEST_ASSERT_SUPPORTED_ATTRIBUTES(attributes)				\
+	TEST_ASSERT(!attributes || attributes == KVM_MEMORY_ATTRIBUTE_PRIVATE,	\
+		    "Update me to support multiple attributes!")
+
 static inline void vm_set_memory_attributes(struct kvm_vm *vm, uint64_t gpa,
 					    uint64_t size, uint64_t attributes)
 {
@@ -404,12 +422,7 @@ static inline void vm_set_memory_attributes(struct kvm_vm *vm, uint64_t gpa,
 		.flags = 0,
 	};
 
-	/*
-	 * KVM_SET_MEMORY_ATTRIBUTES2 overwrites _all_ attributes.  These flows
-	 * need significant enhancements to support multiple attributes.
-	 */
-	TEST_ASSERT(!attributes || attributes == KVM_MEMORY_ATTRIBUTE_PRIVATE,
-		    "Update me to support multiple attributes!");
+	TEST_ASSERT_SUPPORTED_ATTRIBUTES(attributes);
 
 	__TEST_REQUIRE(kvm_check_cap(KVM_CAP_MEMORY_ATTRIBUTES2) > 0,
 		       "No valid attributes for VM fd ioctl!");
@@ -417,7 +430,6 @@ static inline void vm_set_memory_attributes(struct kvm_vm *vm, uint64_t gpa,
 	vm_ioctl(vm, KVM_SET_MEMORY_ATTRIBUTES2, &attr);
 }
 
-
 static inline void vm_mem_set_private(struct kvm_vm *vm, uint64_t gpa,
 				      uint64_t size)
 {
@@ -430,6 +442,69 @@ static inline void vm_mem_set_shared(struct kvm_vm *vm, uint64_t gpa,
 	vm_set_memory_attributes(vm, gpa, size, 0);
 }
 
+static inline int __gmem_set_memory_attributes(int fd, loff_t offset,
+					       uint64_t size,
+					       uint64_t attributes,
+					       loff_t *error_offset)
+{
+	struct kvm_memory_attributes2 attr = {
+		.attributes = attributes,
+		.offset = offset,
+		.size = size,
+		.flags = 0,
+	};
+	int r;
+
+	TEST_ASSERT_SUPPORTED_ATTRIBUTES(attributes);
+
+	r = __gmem_ioctl(fd, KVM_SET_MEMORY_ATTRIBUTES2, &attr);
+	if (r)
+		*error_offset = attr.error_offset;
+	return r;
+}
+
+static inline int __gmem_set_private(int fd, loff_t offset, uint64_t size,
+				     loff_t *error_offset)
+{
+	return __gmem_set_memory_attributes(fd, offset, size,
+					    KVM_MEMORY_ATTRIBUTE_PRIVATE,
+					    error_offset);
+}
+
+static inline int __gmem_set_shared(int fd, loff_t offset, uint64_t size,
+				    loff_t *error_offset)
+{
+	return __gmem_set_memory_attributes(fd, offset, size, 0, error_offset);
+}
+
+static inline void gmem_set_memory_attributes(int fd, loff_t offset,
+					      uint64_t size, uint64_t attributes)
+{
+	struct kvm_memory_attributes2 attr = {
+		.attributes = attributes,
+		.offset = offset,
+		.size = size,
+		.flags = 0,
+	};
+
+	TEST_ASSERT_SUPPORTED_ATTRIBUTES(attributes);
+
+	__TEST_REQUIRE(kvm_check_cap(KVM_CAP_GUEST_MEMFD_MEMORY_ATTRIBUTES) > 0,
+		       "No valid attributes for guest_memfd ioctl!");
+
+	gmem_ioctl(fd, KVM_SET_MEMORY_ATTRIBUTES2, &attr);
+}
+
+static inline void gmem_set_private(int fd, loff_t offset, uint64_t size)
+{
+	gmem_set_memory_attributes(fd, offset, size, KVM_MEMORY_ATTRIBUTE_PRIVATE);
+}
+
+static inline void gmem_set_shared(int fd, loff_t offset, uint64_t size)
+{
+	gmem_set_memory_attributes(fd, offset, size, 0);
+}
+
 void vm_guest_mem_fallocate(struct kvm_vm *vm, uint64_t gpa, uint64_t size,
 			    bool punch_hole);
 
-- 
2.53.0.rc1.225.gd81095ad13-goog