[kvm-unit-tests PATCH 1/2] x86: vmx: Add test for L2 change of CR4.OSXSAVE

[Jim Mattson <jmattson@google.com>]

If L1 allows L2 to modify CR4.OSXSAVE, then L0 kvm recalculates the
guest's CPUID.01H:ECX.OSXSAVE bit when the L2 guest changes
CR4.OSXSAVE via MOV-to-CR4. Verify that kvm also recalculates this
CPUID bit when loading L1's CR4 from the "host CR4" field of the
VMCS12.

Signed-off-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Ricardo Koller <ricarkol@google.com>
Reviewed-by: Peter Shier <pshier@google.com>
---
 lib/x86/processor.h | 52 +++++++++++++++++++++++++--------------------
 x86/vmx_tests.c     | 34 +++++++++++++++++++++++++++++
 2 files changed, 63 insertions(+), 23 deletions(-)

diff --git a/lib/x86/processor.h b/lib/x86/processor.h
index c2c487c..79ebbd1 100644
--- a/lib/x86/processor.h
+++ b/lib/x86/processor.h
@@ -26,30 +26,31 @@
 #define PF_VECTOR 14
 #define AC_VECTOR 17
 
-#define X86_CR0_PE     0x00000001
-#define X86_CR0_MP     0x00000002
-#define X86_CR0_EM     0x00000004
-#define X86_CR0_TS     0x00000008
-#define X86_CR0_WP     0x00010000
-#define X86_CR0_AM     0x00040000
-#define X86_CR0_NW     0x20000000
-#define X86_CR0_CD     0x40000000
-#define X86_CR0_PG     0x80000000
+#define X86_CR0_PE	0x00000001
+#define X86_CR0_MP	0x00000002
+#define X86_CR0_EM	0x00000004
+#define X86_CR0_TS	0x00000008
+#define X86_CR0_WP	0x00010000
+#define X86_CR0_AM	0x00040000
+#define X86_CR0_NW	0x20000000
+#define X86_CR0_CD	0x40000000
+#define X86_CR0_PG	0x80000000
 #define X86_CR3_PCID_MASK 0x00000fff
-#define X86_CR4_TSD    0x00000004
-#define X86_CR4_DE     0x00000008
-#define X86_CR4_PSE    0x00000010
-#define X86_CR4_PAE    0x00000020
-#define X86_CR4_MCE    0x00000040
-#define X86_CR4_PGE    0x00000080
-#define X86_CR4_PCE    0x00000100
-#define X86_CR4_UMIP   0x00000800
-#define X86_CR4_LA57   0x00001000
-#define X86_CR4_VMXE   0x00002000
-#define X86_CR4_PCIDE  0x00020000
-#define X86_CR4_SMEP   0x00100000
-#define X86_CR4_SMAP   0x00200000
-#define X86_CR4_PKE    0x00400000
+#define X86_CR4_TSD	0x00000004
+#define X86_CR4_DE	0x00000008
+#define X86_CR4_PSE	0x00000010
+#define X86_CR4_PAE	0x00000020
+#define X86_CR4_MCE	0x00000040
+#define X86_CR4_PGE	0x00000080
+#define X86_CR4_PCE	0x00000100
+#define X86_CR4_UMIP	0x00000800
+#define X86_CR4_LA57	0x00001000
+#define X86_CR4_VMXE	0x00002000
+#define X86_CR4_PCIDE	0x00020000
+#define X86_CR4_OSXSAVE	0x00040000
+#define X86_CR4_SMEP	0x00100000
+#define X86_CR4_SMAP	0x00200000
+#define X86_CR4_PKE	0x00400000
 
 #define X86_EFLAGS_CF    0x00000001
 #define X86_EFLAGS_FIXED 0x00000002
@@ -609,4 +610,9 @@ static inline int cpu_has_efer_nx(void)
 	return !!(this_cpu_has(X86_FEATURE_NX));
 }
 
+static inline bool cpuid_osxsave(void)
+{
+	return cpuid(1).c & (1 << (X86_FEATURE_OSXSAVE % 32));
+}
+
 #endif
diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c
index d2084ae..301ca85 100644
--- a/x86/vmx_tests.c
+++ b/x86/vmx_tests.c
@@ -8416,6 +8416,39 @@ static void vmx_cr_load_test(void)
 	TEST_ASSERT(!write_cr4_checking(orig_cr4));
 }
 
+static void vmx_cr4_osxsave_test_guest(void)
+{
+	write_cr4(read_cr4() & ~X86_CR4_OSXSAVE);
+}
+
+/*
+ * Ensure that kvm recalculates the L1 guest's CPUID.01H:ECX.OSXSAVE
+ * after VM-exit from an L2 guest that sets CR4.OSXSAVE to a different
+ * value than in L1.
+ */
+static void vmx_cr4_osxsave_test(void)
+{
+	if (!this_cpu_has(X86_FEATURE_XSAVE)) {
+		report_skip("XSAVE not detected");
+		return;
+	}
+
+	if (!(read_cr4() & X86_CR4_OSXSAVE)) {
+		unsigned long cr4 = read_cr4() | X86_CR4_OSXSAVE;
+
+		write_cr4(cr4);
+		vmcs_write(GUEST_CR4, cr4);
+		vmcs_write(HOST_CR4, cr4);
+	}
+
+	TEST_ASSERT(cpuid_osxsave());
+
+	test_set_guest(vmx_cr4_osxsave_test_guest);
+	enter_guest();
+
+	TEST_ASSERT(cpuid_osxsave());
+}
+
 static void vmx_nm_test_guest(void)
 {
 	write_cr0(read_cr0() | X86_CR0_TS);
@@ -10496,6 +10529,7 @@ struct vmx_test vmx_tests[] = {
 	TEST(vmx_vmcs_shadow_test),
 	/* Regression tests */
 	TEST(vmx_cr_load_test),
+	TEST(vmx_cr4_osxsave_test),
 	TEST(vmx_nm_test),
 	TEST(vmx_db_test),
 	TEST(vmx_nmi_window_test),
-- 
2.29.1.341.ge80a0c044ae-goog