selftests: kvm: move vm_xsave_req_perm call to amx_test

There is no need for tests other than amx_test to enable dynamic xsave
states.  Remove the call to vm_xsave_req_perm from generic code,
and move it inside the test.  While at it, allow customizing the bit
that is requested, so that future tests can use it differently.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

tools/testing/selftests/kvm/include/kvm_util_base.h

@@ -345,7 +345,6 @@ struct kvm_vm *vm_create_with_vcpus(enum vm_guest_mode mode, uint32_t nr_vcpus,
  *   guest_code - The vCPU's entry point
  */
 void vm_vcpu_add_default(struct kvm_vm *vm, uint32_t vcpuid, void *guest_code);
-void vm_xsave_req_perm(void);
 
 bool vm_is_unrestricted_guest(struct kvm_vm *vm);
 

tools/testing/selftests/kvm/include/x86_64/processor.h

@@ -458,6 +458,7 @@ uint64_t kvm_hypercall(uint64_t nr, uint64_t a0, uint64_t a1, uint64_t a2,
 struct kvm_cpuid2 *kvm_get_supported_hv_cpuid(void);
 void vcpu_set_hv_cpuid(struct kvm_vm *vm, uint32_t vcpuid);
 struct kvm_cpuid2 *vcpu_get_supported_hv_cpuid(struct kvm_vm *vm, uint32_t vcpuid);
+void vm_xsave_req_perm(int bit);
 
 enum x86_page_size {
 	X86_PAGE_SIZE_4K = 0,

tools/testing/selftests/kvm/lib/kvm_util.c

@@ -393,13 +393,6 @@ struct kvm_vm *vm_create_with_vcpus(enum vm_guest_mode mode, uint32_t nr_vcpus,
 	struct kvm_vm *vm;
 	int i;
 
-#ifdef __x86_64__
-	/*
-	 * Permission needs to be requested before KVM_SET_CPUID2.
-	 */
-	vm_xsave_req_perm();
-#endif
-
 	/* Force slot0 memory size not small than DEFAULT_GUEST_PHY_PAGES */
 	if (slot0_mem_pages < DEFAULT_GUEST_PHY_PAGES)
 		slot0_mem_pages = DEFAULT_GUEST_PHY_PAGES;

tools/testing/selftests/kvm/lib/x86_64/processor.c

@@ -665,16 +665,16 @@ static bool is_xfd_supported(void)
 	return !!(eax & CPUID_XFD_BIT);
 }
 
-void vm_xsave_req_perm(void)
+void vm_xsave_req_perm(int bit)
 {
-	unsigned long bitmask;
+	u64 bitmask;
 	long rc;
 
 	if (!is_xfd_supported())
-		return;
+		exit(KSFT_SKIP);
+
+	rc = syscall(SYS_arch_prctl, ARCH_REQ_XCOMP_GUEST_PERM, bit);
 
-	rc = syscall(SYS_arch_prctl, ARCH_REQ_XCOMP_GUEST_PERM,
-		     XSTATE_XTILE_DATA_BIT);
 	/*
 	 * The older kernel version(<5.15) can't support
 	 * ARCH_REQ_XCOMP_GUEST_PERM and directly return.
@@ -684,7 +684,7 @@ void vm_xsave_req_perm(void)
 
 	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(bitmask & XFEATURE_XTILE_MASK,
+	TEST_ASSERT(bitmask & (1ULL << bit),
 		    "prctl(ARCH_REQ_XCOMP_GUEST_PERM) failure bitmask=0x%lx",
 		    bitmask);
 }

tools/testing/selftests/kvm/x86_64/amx_test.c

@@ -329,6 +329,8 @@ int main(int argc, char *argv[])
 	u32 amx_offset;
 	int stage, ret;
 
+	vm_xsave_req_perm(XSTATE_XTILE_DATA_BIT);
+
 	/* Create VM */
 	vm = vm_create_default(VCPU_ID, 0, guest_code);