selftests: kvm: replace numbered sync points with actions

Rework the guest=>host syncs in the AMX test to use named actions instead
of arbitrary, incrementing numbers.  The "stage" of the test has no real
meaning, what matters is what action the test wants the host to perform.
The incrementing numbers are somewhat helpful for triaging failures, but
fully debugging failures almost always requires a much deeper dive into
the test (and KVM).

Using named actions not only makes it easier to extend the test without
having to shift all sync point numbers, it makes the code easier to read.

[Commit message by Sean Christopherson]

Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Author: bonzini

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

@@ -124,27 +124,35 @@ static void set_tilecfg(struct tile_config *cfg)
 	}
 }
 
+enum {
+	/* Check TMM0 against tiledata */
+	TEST_COMPARE_TILEDATA = 1,
+
+	/* Full VM save/restore */
+	TEST_SAVE_RESTORE = 2,
+};
+
 static void __attribute__((__flatten__)) guest_code(struct tile_config *amx_cfg,
 						    struct tile_data *tiledata,
 						    struct xstate *xstate)
 {
 	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_COMPARE_TILEDATA | TEST_SAVE_RESTORE);
 	__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 +162,8 @@ 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 +176,32 @@ 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);
+	GUEST_SYNC(TEST_COMPARE_TILEDATA | TEST_SAVE_RESTORE);
 
 	GUEST_DONE();
 }
 
 void guest_nm_handler(struct ex_regs *regs)
 {
 	/* Check if #NM is triggered by XFEATURE_MASK_XTILE_DATA */
-	GUEST_SYNC(7);
+	GUEST_SYNC(TEST_SAVE_RESTORE);
 	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);
 }
 
 int main(int argc, char *argv[])
@@ -244,6 +254,7 @@ 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);
@@ -253,20 +264,9 @@ 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_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.
@@ -279,11 +279,25 @@ int main(int argc, char *argv[])
 				ret = memcmp(amx_start, tiles_data, TILE_SIZE);
 				TEST_ASSERT(ret == 0, "memcmp failed, ret=%d", ret);
 				kvm_x86_state_cleanup(state);
-				break;
-			case 9:
-				fprintf(stderr,
-				"GUEST_SYNC(%ld), #NM exception and enable amx\n", uc.args[1]);
-				break;
+			}
+			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);
+
+				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 +307,6 @@ 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);