[PATCH 8/8][KVM nVMX]: Test "load IA32_PERF_GLOBAL_CTRL" controls on vmentry of nested guests

[Krish Sadhukhan <krish.sadhukhan@xxxxxxxxxx>]

 ...to verify KVM performs the appropriate consistency checks for loading
IA32_PERF_GLOBAL_CTRL as part of running a nested guest.

According to section "Checks on Host Control Registers and MSRs" in Intel
SDM vol 3C, the following checks are performed on vmentry of nested guests:

    If the "load IA32_PERF_GLOBAL_CTRL" VM-exit control is 1, bits reserved
    in the IA32_PERF_GLOBAL_CTRL MSR must be 0 in the field for that register.

Signed-off-by: Krish Sadhukhan <krish.sadhukhan@xxxxxxxxxx>
Reviewed-by: Karl Heubaum <karl.heubaum@xxxxxxxxxx>
---
 x86/vmx_tests.c | 59 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 59 insertions(+)

diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c
index 66a87f6..85fa8d5 100644
--- a/x86/vmx_tests.c
+++ b/x86/vmx_tests.c
@@ -4995,6 +4995,63 @@ static void test_sysenter_field(u32 field, const char *name)
 	vmcs_write(field, addr_saved);
 }
 
+#define	PERF_GLOBAL_CTRL_VALID_BITS	0x0000000700000003
+
+static void test_perf_global_ctl(u32 field, const char * field_name,
+				 u32 ctrl_field, u64 ctrl_bit)
+{
+	u32 ctrl_saved = vmcs_read(ctrl_field);
+	u64 perf_global_saved = vmcs_read(field);
+	u64 i, val;
+
+	vmcs_write(ctrl_field, ctrl_saved & ~ctrl_bit);
+	for (i = 0; i < 64; i++) {
+		val = 1ull << i;
+		vmcs_write(field, val);
+		report_prefix_pushf("\"load IA32_PERF_GLOBAL_CTRL\" "
+		    "VM-exit control is off, HOST_PERF_GLOBAL_CTRL %lx", val);
+		test_vmx_vmlaunch(0, false);
+		report_prefix_pop();
+	}
+
+	vmcs_write(ctrl_field, ctrl_saved | ctrl_bit);
+	for (i = 0; i < 64; i++) {
+		val = 1ull << i;
+		vmcs_write(field, val);
+		report_prefix_pushf("\"load IA32_PERF_GLOBAL_CTRL\" "
+		    "VM-exit control is on, HOST_PERF_GLOBAL_CTRL %lx", val);
+		if (PERF_GLOBAL_CTRL_VALID_BITS & (1ull << i)) {
+			test_vmx_vmlaunch(0, false);
+		} else {
+			test_vmx_vmlaunch(VMXERR_ENTRY_INVALID_HOST_STATE_FIELD,
+					  false);
+		}
+		report_prefix_pop();
+	}
+
+	vmcs_write(ctrl_field, ctrl_saved);
+	vmcs_write(field, perf_global_saved);
+}
+
+/*
+ * If the "load IA32_PERF_GLOBAL_CTRL" VM-exit control is 1, bits reserved
+ * in the IA32_PERF_GLOBAL_CTRL MSR must be 0 in the field for that
+ * register.
+ *
+ *  [Intel SDM]
+ */
+static void test_host_perf_global_ctl(void)
+{
+	if (!(ctrl_exit_rev.clr & EXI_LOAD_PERF)) {
+		printf("\"load IA32_PERF_GLOBAL_CTRL\" VM-exit control not "
+		       "supported\n");
+		return;
+	}
+
+	test_perf_global_ctl(HOST_PERF_GLOBAL_CTRL, "HOST_PERF_GLOBAL_CTRL",
+			     EXI_CONTROLS, EXI_LOAD_PERF);
+}
+
 /*
  * Check that the virtual CPU checks the VMX Host State Area as
  * documented in the Intel SDM.
@@ -5010,6 +5067,8 @@ static void vmx_host_state_area_test(void)
 
 	test_sysenter_field(HOST_SYSENTER_ESP, "HOST_SYSENTER_ESP");
 	test_sysenter_field(HOST_SYSENTER_EIP, "HOST_SYSENTER_EIP");
+
+	test_host_perf_global_ctl();
 }
 
 static bool valid_vmcs_for_vmentry(void)
-- 
2.17.2