[RFC PATCH 2/2] selftests: kvm: Use the KVM API to enable dynamic XSTATE features

["Chang S. Bae" <chang.seok.bae@xxxxxxxxx>]

Use the KVM_X86_XCOMP_GUEST_PERM attribute, instead of the x86-specific prctl()
options.

Signed-off-by: Chang S. Bae <chang.seok.bae@xxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: Yang Zhong <yang.zhong@xxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: kvm@xxxxxxxxxxxxxxx
Cc: linux-kselftest@xxxxxxxxxxxxxxx
---
 tools/arch/x86/include/uapi/asm/kvm.h         |  1 +
 .../selftests/kvm/lib/x86_64/processor.c      | 22 ++++++++++++++-----
 2 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/tools/arch/x86/include/uapi/asm/kvm.h b/tools/arch/x86/include/uapi/asm/kvm.h
index 46de10a809ec..6ab9a2b38061 100644
--- a/tools/arch/x86/include/uapi/asm/kvm.h
+++ b/tools/arch/x86/include/uapi/asm/kvm.h
@@ -461,6 +461,7 @@ struct kvm_sync_regs {
 
 /* attributes for system fd (group 0) */
 #define KVM_X86_XCOMP_GUEST_SUPP	0
+#define KVM_X86_XCOMP_GUEST_PERM	1
 
 struct kvm_vmx_nested_state_data {
 	__u8 vmcs12[KVM_STATE_NESTED_VMX_VMCS_SIZE];
diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
index 2e6e61bbe81b..b67f28676d15 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
@@ -593,8 +593,6 @@ void __vm_xsave_require_permission(int bit, const char *name)
 
 	kvm_fd = open_kvm_dev_path_or_exit();
 	rc = __kvm_ioctl(kvm_fd, KVM_GET_DEVICE_ATTR, &attr);
-	close(kvm_fd);
-
 	if (rc == -1 && (errno == ENXIO || errno == EINVAL))
 		__TEST_REQUIRE(0, "KVM_X86_XCOMP_GUEST_SUPP not supported");
 
@@ -603,13 +601,25 @@ void __vm_xsave_require_permission(int bit, const char *name)
 	__TEST_REQUIRE(bitmask & (1ULL << bit),
 		       "Required XSAVE feature '%s' not supported", name);
 
-	TEST_REQUIRE(!syscall(SYS_arch_prctl, ARCH_REQ_XCOMP_GUEST_PERM, bit));
+	attr.attr = KVM_X86_XCOMP_GUEST_PERM;
+	attr.addr = (unsigned long) bit;
+	rc = __kvm_ioctl(kvm_fd, KVM_SET_DEVICE_ATTR, &attr);
+	if (rc == -1 && (errno == ENXIO || errno == EINVAL))
+		__TEST_REQUIRE(0, "KVM_X86_XCOMP_GUEST_PERM not supported");
 
-	rc = syscall(SYS_arch_prctl, ARCH_GET_XCOMP_GUEST_PERM, &bitmask);
-	TEST_ASSERT(rc == 0, "prctl(ARCH_GET_XCOMP_GUEST_PERM) error: %ld", rc);
+	TEST_ASSERT(rc == 0, "KVM_SET_DEVICE_ATTR(0, KVM_X86_XCOMP_GUEST_PERM) error: %ld", rc);
+
+	attr.addr = (unsigned long) &bitmask;
+	rc = __kvm_ioctl(kvm_fd, KVM_GET_DEVICE_ATTR, &attr);
+	if (rc == -1 && (errno == ENXIO || errno == EINVAL))
+		__TEST_REQUIRE(0, "KVM_X86_XCOMP_GUEST_PERM not supported");
+
+	TEST_ASSERT(rc == 0, "KVM_GET_DEVICE_ATTR(0, KVM_X86_XCOMP_GUEST_PERM) error: %ld", rc);
 	TEST_ASSERT(bitmask & (1ULL << bit),
-		    "prctl(ARCH_REQ_XCOMP_GUEST_PERM) failure bitmask=0x%lx",
+		    "KVM_GET_DEVICE_ATTR(0, KVM_X86_XCOMP_GUEST_PERM) failure bitmask=0x%lx",
 		    bitmask);
+
+	close(kvm_fd);
 }
 
 struct kvm_vcpu *vm_arch_vcpu_add(struct kvm_vm *vm, uint32_t vcpu_id,
-- 
2.17.1