Merge: KVM: Host kernel panics with "unexpected #NM exception" at restore_fpregs_from_fpstate

MR: https://gitlab.com/redhat/rhel/src/kernel/rhel-10/-/merge_requests/797

Until now, fpregs->xfd acted as both the guest value and the value that
the host used when executing XSAVES and XRSTORS.  This is wrong; the
data in the guest's FPU might not be initialized even if a bit is
set in XFD, and when that happens XRSTORing the guest FPU will fail
with a #NM exception.

Instead, store the value of XFD together with XFD_ERR in struct
fpu_guest, and synchronize it in fpregs_ensure_guest_state().

JIRA: https://issues.redhat.com/browse/RHEL-148618

Tested: kvm unit tests and selftests on Intel and AMD machine.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>

Approved-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Approved-by: Steve Best <sbest@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>

Merged-by: CKI GitLab Kmaint Pipeline Bot <26919896-cki-kmaint-pipeline-bot@users.noreply.gitlab.com>

arch/x86/include/uapi/asm/kvm.h

@@ -35,6 +35,11 @@
 #define MC_VECTOR 18
 #define XM_VECTOR 19
 #define VE_VECTOR 20
+#define CP_VECTOR 21
+
+#define HV_VECTOR 28
+#define VC_VECTOR 29
+#define SX_VECTOR 30
 
 /* Select x86 specific features in <linux/kvm.h> */
 #define __KVM_HAVE_PIT

arch/x86/kernel/fpu/core.c

@@ -294,10 +294,29 @@ EXPORT_SYMBOL_GPL(fpu_enable_guest_xfd_features);
 #ifdef CONFIG_X86_64
 void fpu_update_guest_xfd(struct fpu_guest *guest_fpu, u64 xfd)
 {
+	struct fpstate *fpstate = guest_fpu->fpstate;
+
 	fpregs_lock();
-	guest_fpu->fpstate->xfd = xfd;
-	if (guest_fpu->fpstate->in_use)
-		xfd_update_state(guest_fpu->fpstate);
+
+	/*
+	 * KVM's guest ABI is that setting XFD[i]=1 *can* immediately revert the
+	 * save state to its initial configuration.  Likewise, KVM_GET_XSAVE does
+	 * the same as XSAVE and returns XSTATE_BV[i]=0 whenever XFD[i]=1.
+	 *
+	 * If the guest's FPU state is in hardware, just update XFD: the XSAVE
+	 * in fpu_swap_kvm_fpstate will clear XSTATE_BV[i] whenever XFD[i]=1.
+	 *
+	 * If however the guest's FPU state is NOT resident in hardware, clear
+	 * disabled components in XSTATE_BV now, or a subsequent XRSTOR will
+	 * attempt to load disabled components and generate #NM _in the host_.
+	 */
+	if (xfd && test_thread_flag(TIF_NEED_FPU_LOAD))
+		fpstate->regs.xsave.header.xfeatures &= ~xfd;
+
+	fpstate->xfd = xfd;
+	if (fpstate->in_use)
+		xfd_update_state(fpstate);
+
 	fpregs_unlock();
 }
 EXPORT_SYMBOL_GPL(fpu_update_guest_xfd);
@@ -405,6 +424,13 @@ int fpu_copy_uabi_to_guest_fpstate(struct fpu_guest *gfpu, const void *buf,
 	if (ustate->xsave.header.xfeatures & ~xcr0)
 		return -EINVAL;
 
+	/*
+	 * Disabled features must be in their initial state, otherwise XRSTOR
+	 * causes an exception.
+	 */
+	if (WARN_ON_ONCE(ustate->xsave.header.xfeatures & kstate->xfd))
+		return -EINVAL;
+
 	/*
 	 * Nullify @vpkru to preserve its current value if PKRU's bit isn't set
 	 * in the header.  KVM's odd ABI is to leave PKRU untouched in this

arch/x86/kvm/trace.h

@@ -461,8 +461,9 @@ TRACE_EVENT(kvm_inj_virq,
 
 #define kvm_trace_sym_exc						\
 	EXS(DE), EXS(DB), EXS(BP), EXS(OF), EXS(BR), EXS(UD), EXS(NM),	\
-	EXS(DF), EXS(TS), EXS(NP), EXS(SS), EXS(GP), EXS(PF),		\
-	EXS(MF), EXS(AC), EXS(MC)
+	EXS(DF), EXS(TS), EXS(NP), EXS(SS), EXS(GP), EXS(PF), EXS(MF),	\
+	EXS(AC), EXS(MC), EXS(XM), EXS(VE), EXS(CP),			\
+	EXS(HV), EXS(VC), EXS(SX)
 
 /*
  * Tracepoint for kvm interrupt injection:

arch/x86/kvm/x86.c

@@ -5676,9 +5676,18 @@ static int kvm_vcpu_ioctl_x86_get_xsave(struct kvm_vcpu *vcpu,
 static int kvm_vcpu_ioctl_x86_set_xsave(struct kvm_vcpu *vcpu,
 					struct kvm_xsave *guest_xsave)
 {
+	union fpregs_state *xstate = (union fpregs_state *)guest_xsave->region;
+
 	if (fpstate_is_confidential(&vcpu->arch.guest_fpu))
 		return vcpu->kvm->arch.has_protected_state ? -EINVAL : 0;
 
+	/*
+	 * For backwards compatibility, do not expect disabled features to be in
+	 * their initial state.  XSTATE_BV[i] must still be cleared whenever
+	 * XFD[i]=1, or XRSTOR would cause a #NM.
+	 */
+	xstate->xsave.header.xfeatures &= ~vcpu->arch.guest_fpu.fpstate->xfd;
+
 	return fpu_copy_uabi_to_guest_fpstate(&vcpu->arch.guest_fpu,
 					      guest_xsave->region,
 					      kvm_caps.supported_xcr0,

tools/testing/selftests/kvm/include/x86/processor.h

@@ -34,6 +34,8 @@ extern uint64_t guest_tsc_khz;
 
 #define NMI_VECTOR		0x02
 
+const char *ex_str(int vector);
+
 #define X86_EFLAGS_FIXED	 (1u << 1)
 
 #define X86_CR4_VME		(1ul << 0)
@@ -1184,6 +1186,12 @@ struct idt_entry {
 void vm_install_exception_handler(struct kvm_vm *vm, int vector,
 			void (*handler)(struct ex_regs *));
 
+/*
+ * Exception fixup morphs #DE to an arbitrary magic vector so that '0' can be
+ * used to signal "no expcetion".
+ */
+#define KVM_MAGIC_DE_VECTOR 0xff
+
 /* If a toddler were to say "abracadabra". */
 #define KVM_EXCEPTION_MAGIC 0xabacadabaULL
 

tools/testing/selftests/kvm/lib/x86/processor.c

@@ -24,6 +24,39 @@ bool host_cpu_is_intel;
 bool is_forced_emulation_enabled;
 uint64_t guest_tsc_khz;
 
+const char *ex_str(int vector)
+{
+	switch (vector) {
+#define VEC_STR(v) case v##_VECTOR: return "#" #v
+	case DE_VECTOR: return "no exception";
+	case KVM_MAGIC_DE_VECTOR: return "#DE";
+	VEC_STR(DB);
+	VEC_STR(NMI);
+	VEC_STR(BP);
+	VEC_STR(OF);
+	VEC_STR(BR);
+	VEC_STR(UD);
+	VEC_STR(NM);
+	VEC_STR(DF);
+	VEC_STR(TS);
+	VEC_STR(NP);
+	VEC_STR(SS);
+	VEC_STR(GP);
+	VEC_STR(PF);
+	VEC_STR(MF);
+	VEC_STR(AC);
+	VEC_STR(MC);
+	VEC_STR(XM);
+	VEC_STR(VE);
+	VEC_STR(CP);
+	VEC_STR(HV);
+	VEC_STR(VC);
+	VEC_STR(SX);
+	default: return "#??";
+#undef VEC_STR
+	}
+}
+
 static void regs_dump(FILE *stream, struct kvm_regs *regs, uint8_t indent)
 {
 	fprintf(stream, "%*srax: 0x%.16llx rbx: 0x%.16llx "
@@ -558,7 +591,7 @@ static bool kvm_fixup_exception(struct ex_regs *regs)
 		return false;
 
 	if (regs->vector == DE_VECTOR)
-		return false;
+		regs->vector = KVM_MAGIC_DE_VECTOR;
 
 	regs->rip = regs->r11;
 	regs->r9 = regs->vector;

tools/testing/selftests/kvm/x86/amx_test.c

@@ -69,6 +69,12 @@ static inline void __tileloadd(void *tile)
 		     : : "a"(tile), "d"(0));
 }
 
+static inline int tileloadd_safe(void *tile)
+{
+	return kvm_asm_safe(".byte 0xc4,0xe2,0x7b,0x4b,0x04,0x10",
+			    "a"(tile), "d"(0));
+}
+
 static inline void __tilerelease(void)
 {
 	asm volatile(".byte 0xc4, 0xe2, 0x78, 0x49, 0xc0" ::);
@@ -124,27 +130,52 @@ static void set_tilecfg(struct tile_config *cfg)
 	}
 }
 
+enum {
+	/* Retrieve TMM0 from guest, stash it for TEST_RESTORE_TILEDATA */
+	TEST_SAVE_TILEDATA = 1,
+
+	/* Check TMM0 against tiledata */
+	TEST_COMPARE_TILEDATA = 2,
+
+	/* Restore TMM0 from earlier save */
+	TEST_RESTORE_TILEDATA = 4,
+
+	/* Full VM save/restore */
+	TEST_SAVE_RESTORE = 8,
+};
+
 static void __attribute__((__flatten__)) guest_code(struct tile_config *amx_cfg,
 						    struct tile_data *tiledata,
 						    struct xstate *xstate)
 {
+	int vector;
+
 	GUEST_ASSERT(this_cpu_has(X86_FEATURE_XSAVE) &&
 		     this_cpu_has(X86_FEATURE_OSXSAVE));
 	check_xtile_info();
-	GUEST_SYNC(1);
+	GUEST_SYNC(TEST_SAVE_RESTORE);
 
 	/* xfd=0, enable amx */
 	wrmsr(MSR_IA32_XFD, 0);
-	GUEST_SYNC(2);
+	GUEST_SYNC(TEST_SAVE_RESTORE);
 	GUEST_ASSERT(rdmsr(MSR_IA32_XFD) == 0);
 	set_tilecfg(amx_cfg);
 	__ldtilecfg(amx_cfg);
-	GUEST_SYNC(3);
+	GUEST_SYNC(TEST_SAVE_RESTORE);
 	/* Check save/restore when trap to userspace */
 	__tileloadd(tiledata);
-	GUEST_SYNC(4);
+	GUEST_SYNC(TEST_SAVE_TILEDATA | TEST_COMPARE_TILEDATA | TEST_SAVE_RESTORE);
+
+	/* xfd=0x40000, disable amx tiledata */
+	wrmsr(MSR_IA32_XFD, XFEATURE_MASK_XTILE_DATA);
+
+	/* host tries setting tiledata while guest XFD is set */
+	GUEST_SYNC(TEST_RESTORE_TILEDATA);
+	GUEST_SYNC(TEST_SAVE_RESTORE);
+
+	wrmsr(MSR_IA32_XFD, 0);
 	__tilerelease();
-	GUEST_SYNC(5);
+	GUEST_SYNC(TEST_SAVE_RESTORE);
 	/*
 	 * After XSAVEC, XTILEDATA is cleared in the xstate_bv but is set in
 	 * the xcomp_bv.
@@ -154,6 +185,8 @@ static void __attribute__((__flatten__)) guest_code(struct tile_config *amx_cfg,
 	GUEST_ASSERT(!(xstate->header.xstate_bv & XFEATURE_MASK_XTILE_DATA));
 	GUEST_ASSERT(xstate->header.xcomp_bv & XFEATURE_MASK_XTILE_DATA);
 
+	/* #NM test */
+
 	/* xfd=0x40000, disable amx tiledata */
 	wrmsr(MSR_IA32_XFD, XFEATURE_MASK_XTILE_DATA);
 
@@ -166,32 +199,33 @@ static void __attribute__((__flatten__)) guest_code(struct tile_config *amx_cfg,
 	GUEST_ASSERT(!(xstate->header.xstate_bv & XFEATURE_MASK_XTILE_DATA));
 	GUEST_ASSERT((xstate->header.xcomp_bv & XFEATURE_MASK_XTILE_DATA));
 
-	GUEST_SYNC(6);
+	GUEST_SYNC(TEST_SAVE_RESTORE);
 	GUEST_ASSERT(rdmsr(MSR_IA32_XFD) == XFEATURE_MASK_XTILE_DATA);
 	set_tilecfg(amx_cfg);
 	__ldtilecfg(amx_cfg);
+
 	/* Trigger #NM exception */
-	__tileloadd(tiledata);
-	GUEST_SYNC(10);
+	vector = tileloadd_safe(tiledata);
+	__GUEST_ASSERT(vector == NM_VECTOR,
+		       "Wanted #NM on tileloadd with XFD[18]=1, got %s",
+		       ex_str(vector));
 
-	GUEST_DONE();
-}
-
-void guest_nm_handler(struct ex_regs *regs)
-{
-	/* Check if #NM is triggered by XFEATURE_MASK_XTILE_DATA */
-	GUEST_SYNC(7);
 	GUEST_ASSERT(!(get_cr0() & X86_CR0_TS));
 	GUEST_ASSERT(rdmsr(MSR_IA32_XFD_ERR) == XFEATURE_MASK_XTILE_DATA);
 	GUEST_ASSERT(rdmsr(MSR_IA32_XFD) == XFEATURE_MASK_XTILE_DATA);
-	GUEST_SYNC(8);
+	GUEST_SYNC(TEST_SAVE_RESTORE);
 	GUEST_ASSERT(rdmsr(MSR_IA32_XFD_ERR) == XFEATURE_MASK_XTILE_DATA);
 	GUEST_ASSERT(rdmsr(MSR_IA32_XFD) == XFEATURE_MASK_XTILE_DATA);
 	/* Clear xfd_err */
 	wrmsr(MSR_IA32_XFD_ERR, 0);
 	/* xfd=0, enable amx */
 	wrmsr(MSR_IA32_XFD, 0);
-	GUEST_SYNC(9);
+	GUEST_SYNC(TEST_SAVE_RESTORE);
+
+	__tileloadd(tiledata);
+	GUEST_SYNC(TEST_COMPARE_TILEDATA | TEST_SAVE_RESTORE);
+
+	GUEST_DONE();
 }
 
 int main(int argc, char *argv[])
@@ -200,10 +234,10 @@ int main(int argc, char *argv[])
 	struct kvm_vcpu *vcpu;
 	struct kvm_vm *vm;
 	struct kvm_x86_state *state;
+	struct kvm_x86_state *tile_state = NULL;
 	int xsave_restore_size;
 	vm_vaddr_t amx_cfg, tiledata, xstate;
 	struct ucall uc;
-	u32 amx_offset;
 	int ret;
 
 	/*
@@ -228,9 +262,6 @@ int main(int argc, char *argv[])
 
 	vcpu_regs_get(vcpu, &regs1);
 
-	/* Register #NM handler */
-	vm_install_exception_handler(vm, NM_VECTOR, guest_nm_handler);
-
 	/* amx cfg for guest_code */
 	amx_cfg = vm_vaddr_alloc_page(vm);
 	memset(addr_gva2hva(vm, amx_cfg), 0x0, getpagesize());
@@ -244,6 +275,7 @@ int main(int argc, char *argv[])
 	memset(addr_gva2hva(vm, xstate), 0, PAGE_SIZE * DIV_ROUND_UP(XSAVE_SIZE, PAGE_SIZE));
 	vcpu_args_set(vcpu, 3, amx_cfg, tiledata, xstate);
 
+	int iter = 0;
 	for (;;) {
 		vcpu_run(vcpu);
 		TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
@@ -253,37 +285,47 @@ int main(int argc, char *argv[])
 			REPORT_GUEST_ASSERT(uc);
 			/* NOT REACHED */
 		case UCALL_SYNC:
-			switch (uc.args[1]) {
-			case 1:
-			case 2:
-			case 3:
-			case 5:
-			case 6:
-			case 7:
-			case 8:
-				fprintf(stderr, "GUEST_SYNC(%ld)\n", uc.args[1]);
-				break;
-			case 4:
-			case 10:
-				fprintf(stderr,
-				"GUEST_SYNC(%ld), check save/restore status\n", uc.args[1]);
+			++iter;
+			if (uc.args[1] & TEST_SAVE_TILEDATA) {
+				fprintf(stderr, "GUEST_SYNC #%d, save tiledata\n", iter);
+				tile_state = vcpu_save_state(vcpu);
+			}
+			if (uc.args[1] & TEST_COMPARE_TILEDATA) {
+				fprintf(stderr, "GUEST_SYNC #%d, check TMM0 contents\n", iter);
 
 				/* Compacted mode, get amx offset by xsave area
 				 * size subtract 8K amx size.
 				 */
-				amx_offset = xsave_restore_size - NUM_TILES*TILE_SIZE;
-				state = vcpu_save_state(vcpu);
-				void *amx_start = (void *)state->xsave + amx_offset;
+				u32 amx_offset = xsave_restore_size - NUM_TILES*TILE_SIZE;
+				void *amx_start = (void *)tile_state->xsave + amx_offset;
 				void *tiles_data = (void *)addr_gva2hva(vm, tiledata);
 				/* Only check TMM0 register, 1 tile */
 				ret = memcmp(amx_start, tiles_data, TILE_SIZE);
 				TEST_ASSERT(ret == 0, "memcmp failed, ret=%d", ret);
+			}
+			if (uc.args[1] & TEST_RESTORE_TILEDATA) {
+				fprintf(stderr, "GUEST_SYNC #%d, before KVM_SET_XSAVE\n", iter);
+				vcpu_xsave_set(vcpu, tile_state->xsave);
+				fprintf(stderr, "GUEST_SYNC #%d, after KVM_SET_XSAVE\n", iter);
+			}
+			if (uc.args[1] & TEST_SAVE_RESTORE) {
+				fprintf(stderr, "GUEST_SYNC #%d, save/restore VM state\n", iter);
+				state = vcpu_save_state(vcpu);
+				memset(&regs1, 0, sizeof(regs1));
+				vcpu_regs_get(vcpu, &regs1);
+
+				kvm_vm_release(vm);
+
+				/* Restore state in a new VM.  */
+				vcpu = vm_recreate_with_one_vcpu(vm);
+				vcpu_load_state(vcpu, state);
 				kvm_x86_state_cleanup(state);
-				break;
-			case 9:
-				fprintf(stderr,
-				"GUEST_SYNC(%ld), #NM exception and enable amx\n", uc.args[1]);
-				break;
+
+				memset(&regs2, 0, sizeof(regs2));
+				vcpu_regs_get(vcpu, &regs2);
+				TEST_ASSERT(!memcmp(&regs1, &regs2, sizeof(regs2)),
+					    "Unexpected register values after vcpu_load_state; rdi: %lx rsi: %lx",
+					    (ulong) regs2.rdi, (ulong) regs2.rsi);
 			}
 			break;
 		case UCALL_DONE:
@@ -293,22 +335,6 @@ int main(int argc, char *argv[])
 			TEST_FAIL("Unknown ucall %lu", uc.cmd);
 		}
 
-		state = vcpu_save_state(vcpu);
-		memset(&regs1, 0, sizeof(regs1));
-		vcpu_regs_get(vcpu, &regs1);
-
-		kvm_vm_release(vm);
-
-		/* Restore state in a new VM.  */
-		vcpu = vm_recreate_with_one_vcpu(vm);
-		vcpu_load_state(vcpu, state);
-		kvm_x86_state_cleanup(state);
-
-		memset(&regs2, 0, sizeof(regs2));
-		vcpu_regs_get(vcpu, &regs2);
-		TEST_ASSERT(!memcmp(&regs1, &regs2, sizeof(regs2)),
-			    "Unexpected register values after vcpu_load_state; rdi: %lx rsi: %lx",
-			    (ulong) regs2.rdi, (ulong) regs2.rsi);
 	}
 done:
 	kvm_vm_free(vm);

tools/testing/selftests/kvm/x86/hyperv_features.c

@@ -54,12 +54,12 @@ static void guest_msr(struct msr_data *msr)
 
 	if (msr->fault_expected)
 		__GUEST_ASSERT(vector == GP_VECTOR,
-			       "Expected #GP on %sMSR(0x%x), got vector '0x%x'",
-			       msr->write ? "WR" : "RD", msr->idx, vector);
+			       "Expected #GP on %sMSR(0x%x), got %s",
+			       msr->write ? "WR" : "RD", msr->idx, ex_str(vector));
 	else
 		__GUEST_ASSERT(!vector,
-			       "Expected success on %sMSR(0x%x), got vector '0x%x'",
-			       msr->write ? "WR" : "RD", msr->idx, vector);
+			       "Expected success on %sMSR(0x%x), got %s",
+			       msr->write ? "WR" : "RD", msr->idx, ex_str(vector));
 
 	if (vector || is_write_only_msr(msr->idx))
 		goto done;
@@ -102,12 +102,12 @@ static void guest_hcall(vm_vaddr_t pgs_gpa, struct hcall_data *hcall)
 	vector = __hyperv_hypercall(hcall->control, input, output, &res);
 	if (hcall->ud_expected) {
 		__GUEST_ASSERT(vector == UD_VECTOR,
-			       "Expected #UD for control '%lu', got vector '0x%x'",
-			       hcall->control, vector);
+			       "Expected #UD for control '%lu', got %s",
+			       hcall->control, ex_str(vector));
 	} else {
 		__GUEST_ASSERT(!vector,
-			       "Expected no exception for control '%lu', got vector '0x%x'",
-			       hcall->control, vector);
+			       "Expected no exception for control '%lu', got %s",
+			       hcall->control, ex_str(vector));
 		GUEST_ASSERT_EQ(res, hcall->expect);
 	}
 

tools/testing/selftests/kvm/x86/monitor_mwait_test.c

@@ -30,12 +30,12 @@ do {									\
 									\
 	if (fault_wanted)						\
 		__GUEST_ASSERT((vector) == UD_VECTOR,			\
-			       "Expected #UD on " insn " for testcase '0x%x', got '0x%x'", \
-			       testcase, vector);			\
+			       "Expected #UD on " insn " for testcase '0x%x', got %s", \
+			       testcase, ex_str(vector));		\
 	else								\
 		__GUEST_ASSERT(!(vector),				\
-			       "Expected success on " insn " for testcase '0x%x', got '0x%x'", \
-			       testcase, vector);			\
+			       "Expected success on " insn " for testcase '0x%x', got %s", \
+			       testcase, ex_str(vector));		\
 } while (0)
 
 static void guest_monitor_wait(void *arg)

tools/testing/selftests/kvm/x86/pmu_counters_test.c

@@ -365,8 +365,8 @@ static void test_arch_events(uint8_t pmu_version, uint64_t perf_capabilities,
 
 #define GUEST_ASSERT_PMC_MSR_ACCESS(insn, msr, expect_gp, vector)		\
 __GUEST_ASSERT(expect_gp ? vector == GP_VECTOR : !vector,			\
-	       "Expected %s on " #insn "(0x%x), got vector %u",			\
-	       expect_gp ? "#GP" : "no fault", msr, vector)			\
+	       "Expected %s on " #insn "(0x%x), got %s",			\
+	       expect_gp ? "#GP" : "no fault", msr, ex_str(vector))		\
 
 #define GUEST_ASSERT_PMC_VALUE(insn, msr, val, expected)			\
 	__GUEST_ASSERT(val == expected,					\

tools/testing/selftests/kvm/x86/vmx_pmu_caps_test.c

@@ -57,8 +57,8 @@ static void guest_test_perf_capabilities_gp(uint64_t val)
 	uint8_t vector = wrmsr_safe(MSR_IA32_PERF_CAPABILITIES, val);
 
 	__GUEST_ASSERT(vector == GP_VECTOR,
-		       "Expected #GP for value '0x%lx', got vector '0x%x'",
-		       val, vector);
+		       "Expected #GP for value '0x%lx', got %s",
+		       val, ex_str(vector));
 }
 
 static void guest_code(uint64_t current_val)

tools/testing/selftests/kvm/x86/xcr0_cpuid_test.c

@@ -81,13 +81,13 @@ static void guest_code(void)
 
 	vector = xsetbv_safe(0, XFEATURE_MASK_FP);
 	__GUEST_ASSERT(!vector,
-		       "Expected success on XSETBV(FP), got vector '0x%x'",
-		       vector);
+		       "Expected success on XSETBV(FP), got %s",
+		       ex_str(vector));
 
 	vector = xsetbv_safe(0, supported_xcr0);
 	__GUEST_ASSERT(!vector,
-		       "Expected success on XSETBV(0x%lx), got vector '0x%x'",
-		       supported_xcr0, vector);
+		       "Expected success on XSETBV(0x%lx), got %s",
+		       supported_xcr0, ex_str(vector));
 
 	for (i = 0; i < 64; i++) {
 		if (supported_xcr0 & BIT_ULL(i))
@@ -95,8 +95,8 @@ static void guest_code(void)
 
 		vector = xsetbv_safe(0, supported_xcr0 | BIT_ULL(i));
 		__GUEST_ASSERT(vector == GP_VECTOR,
-			       "Expected #GP on XSETBV(0x%llx), supported XCR0 = %lx, got vector '0x%x'",
-			       BIT_ULL(i), supported_xcr0, vector);
+			       "Expected #GP on XSETBV(0x%llx), supported XCR0 = %lx, got %s",
+			       BIT_ULL(i), supported_xcr0, ex_str(vector));
 	}
 
 	GUEST_DONE();