[PATCH 2/2 v2] kvm-unit-test: nVMX: Test GUEST_DR7 on vmentry of nested guests

[Krish Sadhukhan <krish.sadhukhan@oracle.com>]

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

   If the "load debug controls" VM-entry control is 1,

      - bits 63:32 in the DR7 field must be 0.

Signed-off-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Reviewed-by: Karl Heubaum <karl.heubaum@oracle.com>
Co-developed-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Jim Mattson <jmattson@google.com>
---
 x86/vmx_tests.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c
index fce773c..b773872 100644
--- a/x86/vmx_tests.c
+++ b/x86/vmx_tests.c
@@ -7442,6 +7442,49 @@ static void vmx_host_state_area_test(void)
 	test_load_host_perf_global_ctrl();
 }
 
+/*
+ * If the "load debug controls" VM-entry control is 1, bits 63:32 in
+ * the DR7 field must be 0.
+ *
+ * [Intel SDM]
+ */
+static void test_guest_dr7(void)
+{
+	u32 ent_saved = vmcs_read(ENT_CONTROLS);
+	u64 dr7_saved = vmcs_read(GUEST_DR7);
+	u64 val;
+	int i;
+
+	if (ctrl_enter_rev.set & ENT_LOAD_DBGCTLS) {
+		vmcs_clear_bits(ENT_CONTROLS, ENT_LOAD_DBGCTLS);
+		for (i = 0; i < 64; i++) {
+			val = 1ull << i;
+			vmcs_write(GUEST_DR7, val);
+			enter_guest();
+			report_guest_state_test("ENT_LOAD_DBGCTLS disabled",
+						VMX_VMCALL, val, "GUEST_DR7");
+		}
+	}
+	if (ctrl_enter_rev.clr & ENT_LOAD_DBGCTLS) {
+		vmcs_set_bits(ENT_CONTROLS, ENT_LOAD_DBGCTLS);
+		for (i = 0; i < 64; i++) {
+			val = 1ull << i;
+			vmcs_write(GUEST_DR7, val);
+			if (i < 32)
+				enter_guest();
+			else
+				enter_guest_with_invalid_guest_state();
+			report_guest_state_test("ENT_LOAD_DBGCTLS enabled",
+						i < 32 ? VMX_VMCALL :
+						VMX_ENTRY_FAILURE |
+						VMX_FAIL_STATE,
+						val, "GUEST_DR7");
+		}
+	}
+	vmcs_write(GUEST_DR7, dr7_saved);
+	vmcs_write(ENT_CONTROLS, ent_saved);
+}
+
 /*
  *  If the "load IA32_PAT" VM-entry control is 1, the value of the field
  *  for the IA32_PAT MSR must be one that could be written by WRMSR
@@ -7480,6 +7523,7 @@ static void vmx_guest_state_area_test(void)
 	test_canonical(GUEST_SYSENTER_ESP, "GUEST_SYSENTER_ESP", false);
 	test_canonical(GUEST_SYSENTER_EIP, "GUEST_SYSENTER_EIP", false);
 
+	test_guest_dr7();
 	test_load_guest_pat();
 	test_guest_efer();
 	test_load_guest_perf_global_ctrl();
-- 
2.20.1