[kvm-unit-tests PATCH] x86: nvmx: test max atomic switch MSRs

[Marc Orr <marcorr@google.com>]

Excerise nested VMX's atomic MSR switch code (e.g., VM-entry MSR-load
list) at the maximum number of MSRs supported, as described in the SDM,
in the appendix chapter titled "MISCELLANEOUS DATA".

Suggested-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Marc Orr <marcorr@google.com>
---
 x86/vmx_tests.c | 139 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 139 insertions(+)

diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c
index f035f24a771a..b3b4d5f7cc8f 100644
--- a/x86/vmx_tests.c
+++ b/x86/vmx_tests.c
@@ -2718,6 +2718,11 @@ static void ept_reserved_bit(int bit)
 #define PAGE_2M_ORDER 9
 #define PAGE_1G_ORDER 18
 
+static void *alloc_2m_page(void)
+{
+	return alloc_pages(PAGE_2M_ORDER);
+}
+
 static void *get_1g_page(void)
 {
 	static void *alloc;
@@ -8570,6 +8575,138 @@ static int invalid_msr_entry_failure(struct vmentry_failure *failure)
 	return VMX_TEST_VMEXIT;
 }
 
+enum atomic_switch_msr_scenario {
+	VM_ENTER_LOAD,
+	VM_EXIT_LOAD,
+	VM_EXIT_STORE,
+	ATOMIC_SWITCH_MSR_SCENARIO_END,
+};
+
+static void atomic_switch_msr_limit_test_guest(void)
+{
+	vmcall();
+}
+
+static void populate_msr_list(struct vmx_msr_entry *msr_list, int count)
+{
+	int i;
+
+	for (i = 0; i < count; i++) {
+		msr_list[i].index = MSR_IA32_TSC;
+		msr_list[i].reserved = 0;
+		msr_list[i].value = 0x1234567890abcdef;
+	}
+}
+
+static void configure_atomic_switch_msr_limit_test(
+		struct vmx_msr_entry *test_msr_list, int count)
+{
+	struct vmx_msr_entry *msr_list;
+	const u32 two_mb = 1 << 21;
+	enum atomic_switch_msr_scenario s;
+	enum Encoding addr_field;
+	enum Encoding cnt_field;
+
+	for (s = 0; s < ATOMIC_SWITCH_MSR_SCENARIO_END; s++) {
+		switch (s) {
+		case VM_ENTER_LOAD:
+			addr_field = ENTER_MSR_LD_ADDR;
+			cnt_field = ENT_MSR_LD_CNT;
+			break;
+		case VM_EXIT_LOAD:
+			addr_field = EXIT_MSR_LD_ADDR;
+			cnt_field = EXI_MSR_LD_CNT;
+			break;
+		case VM_EXIT_STORE:
+			addr_field = EXIT_MSR_ST_ADDR;
+			cnt_field = EXI_MSR_ST_CNT;
+			break;
+		default:
+			TEST_ASSERT(false);
+		}
+
+		msr_list = (struct vmx_msr_entry *)vmcs_read(addr_field);
+		memset(msr_list, 0xff, two_mb);
+		if (msr_list == test_msr_list) {
+			populate_msr_list(msr_list, count);
+			vmcs_write(cnt_field, count);
+		} else {
+			vmcs_write(cnt_field, 0);
+		}
+	}
+}
+
+static int max_msr_list_size(void)
+{
+	u32 vmx_misc = rdmsr(MSR_IA32_VMX_MISC);
+	u32 factor = ((vmx_misc & GENMASK(27, 25)) >> 25) + 1;
+
+	return factor * 512;
+}
+
+static void atomic_switch_msr_limit_test(void)
+{
+	struct vmx_msr_entry *msr_list;
+	enum atomic_switch_msr_scenario s;
+
+	/*
+	 * Check for the IA32_TSC MSR,
+	 * available with the "TSC flag" and used to populate the MSR lists.
+	 */
+	if (!(cpuid(1).d & (1 << 4))) {
+		report_skip(__func__);
+		return;
+	}
+
+	/* Set L2 guest. */
+	test_set_guest(atomic_switch_msr_limit_test_guest);
+
+	/* Setup atomic MSR switch lists. */
+	msr_list = alloc_2m_page();
+	vmcs_write(ENTER_MSR_LD_ADDR, virt_to_phys(msr_list));
+	msr_list = alloc_2m_page();
+	vmcs_write(EXIT_MSR_LD_ADDR, virt_to_phys(msr_list));
+	msr_list = alloc_2m_page();
+	vmcs_write(EXIT_MSR_ST_ADDR, virt_to_phys(msr_list));
+
+	/* Execute each test case. */
+	for (s = 0; s < ATOMIC_SWITCH_MSR_SCENARIO_END; s++) {
+		struct vmx_msr_entry *msr_list;
+		int count = max_msr_list_size();
+
+		switch (s) {
+		case VM_ENTER_LOAD:
+			msr_list = (struct vmx_msr_entry *)vmcs_read(
+					ENTER_MSR_LD_ADDR);
+			break;
+		case VM_EXIT_LOAD:
+			msr_list = (struct vmx_msr_entry *)vmcs_read(
+					EXIT_MSR_LD_ADDR);
+			break;
+		case VM_EXIT_STORE:
+			msr_list = (struct vmx_msr_entry *)vmcs_read(
+					EXIT_MSR_ST_ADDR);
+			break;
+		default:
+			report("Bad test scenario, %d.", false, s);
+			continue;
+		}
+
+		configure_atomic_switch_msr_limit_test(msr_list, count);
+		enter_guest();
+		assert_exit_reason(VMX_VMCALL);
+	}
+
+	/* Reset the atomic MSR switch count to 0 for all three lists. */
+	configure_atomic_switch_msr_limit_test(0, 0);
+	/* Proceed past guest's single vmcall instruction. */
+	enter_guest();
+	skip_exit_vmcall();
+	/* Terminate the guest. */
+	enter_guest();
+	skip_exit_vmcall();
+}
+
 
 #define TEST(name) { #name, .v2 = name }
 
@@ -8660,5 +8797,7 @@ struct vmx_test vmx_tests[] = {
 	TEST(ept_access_test_paddr_read_execute_ad_enabled),
 	TEST(ept_access_test_paddr_not_present_page_fault),
 	TEST(ept_access_test_force_2m_page),
+	/* Atomic MSR switch tests. */
+	TEST(atomic_switch_msr_limit_test),
 	{ NULL, NULL, NULL, NULL, NULL, {0} },
 };
-- 
2.23.0.237.gc6a4ce50a0-goog