KVM: selftests: Rework dynamic XFeature helper to take mask, not bit

Take the XFeature mask in __vm_xsave_require_permission() instead of the
bit so that there's no need to define macros for both the bit and the
mask.  Asserting that only a single bit is set and retrieving said bit
is easy enough via log2 helpers.

Opportunistically clean up the error message for the
ARCH_REQ_XCOMP_GUEST_PERM sanity check.

Reviewed-by: Aaron Lewis <aaronlewis@google.com>
Tested-by: Aaron Lewis <aaronlewis@google.com>
Link: https://lore.kernel.org/r/20230405004520.421768-5-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Author: sean-jc

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

@@ -1098,10 +1098,10 @@ uint64_t kvm_hypercall(uint64_t nr, uint64_t a0, uint64_t a1, uint64_t a2,
 uint64_t __xen_hypercall(uint64_t nr, uint64_t a0, void *a1);
 void xen_hypercall(uint64_t nr, uint64_t a0, void *a1);
 
-void __vm_xsave_require_permission(int bit, const char *name);
+void __vm_xsave_require_permission(uint64_t xfeature, const char *name);
 
-#define vm_xsave_require_permission(perm)	\
-	__vm_xsave_require_permission(perm, #perm)
+#define vm_xsave_require_permission(xfeature)	\
+	__vm_xsave_require_permission(xfeature, #xfeature)
 
 enum pg_level {
 	PG_LEVEL_NONE,

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

@@ -697,20 +697,23 @@ uint64_t kvm_get_feature_msr(uint64_t msr_index)
 	return buffer.entry.data;
 }
 
-void __vm_xsave_require_permission(int bit, const char *name)
+void __vm_xsave_require_permission(uint64_t xfeature, const char *name)
 {
 	int kvm_fd;
 	u64 bitmask;
 	long rc;
 	struct kvm_device_attr attr = {
 		.group = 0,
 		.attr = KVM_X86_XCOMP_GUEST_SUPP,
-		.addr = (unsigned long) &bitmask
+		.addr = (unsigned long) &bitmask,
 	};
 
 	TEST_ASSERT(!kvm_supported_cpuid,
 		    "kvm_get_supported_cpuid() cannot be used before ARCH_REQ_XCOMP_GUEST_PERM");
 
+	TEST_ASSERT(is_power_of_2(xfeature),
+		    "Dynamic XFeatures must be enabled one at a time");
+
 	kvm_fd = open_kvm_dev_path_or_exit();
 	rc = __kvm_ioctl(kvm_fd, KVM_GET_DEVICE_ATTR, &attr);
 	close(kvm_fd);
@@ -720,16 +723,16 @@ void __vm_xsave_require_permission(int bit, const char *name)
 
 	TEST_ASSERT(rc == 0, "KVM_GET_DEVICE_ATTR(0, KVM_X86_XCOMP_GUEST_SUPP) error: %ld", rc);
 
-	__TEST_REQUIRE(bitmask & (1ULL << bit),
+	__TEST_REQUIRE(bitmask & xfeature,
 		       "Required XSAVE feature '%s' not supported", name);
 
-	TEST_REQUIRE(!syscall(SYS_arch_prctl, ARCH_REQ_XCOMP_GUEST_PERM, bit));
+	TEST_REQUIRE(!syscall(SYS_arch_prctl, ARCH_REQ_XCOMP_GUEST_PERM, ilog2(xfeature)));
 
 	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 & (1ULL << bit),
-		    "prctl(ARCH_REQ_XCOMP_GUEST_PERM) failure bitmask=0x%lx",
-		    bitmask);
+	TEST_ASSERT(bitmask & xfeature,
+		    "'%s' (0x%lx) not permitted after prctl(ARCH_REQ_XCOMP_GUEST_PERM) perrmited=0x%lx",
+		    name, xfeature, bitmask);
 }
 
 void vcpu_init_cpuid(struct kvm_vcpu *vcpu, const struct kvm_cpuid2 *cpuid)

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

@@ -233,7 +233,7 @@ int main(int argc, char *argv[])
 	 * Note, all off-by-default features must be enabled before anything
 	 * caches KVM_GET_SUPPORTED_CPUID, e.g. before using kvm_cpu_has().
 	 */
-	vm_xsave_require_permission(XSTATE_XTILE_DATA_BIT);
+	vm_xsave_require_permission(XFEATURE_MASK_XTILEDATA);
 
 	TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_XFD));
 	TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_XSAVE));