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@xxxxxxxxxx>
Reviewed-by: Karl Heubaum <karl.heubaum@xxxxxxxxxx>
Co-developed-by: Jim Mattson <jmattson@xxxxxxxxxx>
Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx>
---
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
