CET Shadow Stack(SHSTK) and Indirect Branch Tracking(IBT) are enumerated
via CPUID.(EAX=07H,ECX=0H):ECX[bit 7] and EDX[bit 20] respectively.
Two CET bits (bit 11 and 12) are defined in MSR_IA32_XSS for XSAVES.
They correspond to CET states in user and supervisor mode respectively.
Signed-off-by: Yang Weijiang <weijiang.yang@xxxxxxxxx>
---
target/i386/cpu.c | 42 +++++++++++++++++++++++++++++++++++++++++-
target/i386/cpu.h | 21 +++++++++++++++++++++
2 files changed, 62 insertions(+), 1 deletion(-)
diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index d74d68e319..bae827c8d5 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -1064,6 +1064,16 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
},
[FEAT_XSAVE_XSS_LO] = {
.type = CPUID_FEATURE_WORD,
+ .feat_names = {
+ NULL, NULL, NULL, NULL,
+ NULL, NULL, NULL, NULL,
+ NULL, NULL, NULL, "cet-u",
+ "cet-s", NULL, NULL, NULL,
+ NULL, NULL, NULL, NULL,
+ NULL, NULL, NULL, NULL,
+ NULL, NULL, NULL, NULL,
+ NULL, NULL, NULL, NULL,
+ },
.cpuid = {
.eax = 0xD,
.needs_ecx = true,
@@ -1472,7 +1482,7 @@ typedef struct ExtSaveArea {
} ExtSaveArea;
/* CPUID feature bits available in XSS */
-#define CPUID_XSTATE_XSS_MASK 0
+#define CPUID_XSTATE_XSS_MASK (XSTATE_CET_U_MASK)
static const ExtSaveArea x86_ext_save_areas[] = {
[XSTATE_FP_BIT] = {
@@ -1517,6 +1527,19 @@ static const ExtSaveArea x86_ext_save_areas[] = {
{ .feature = FEAT_7_0_ECX, .bits = CPUID_7_0_ECX_PKU,
.offset = offsetof(X86XSaveArea, pkru_state),
.size = sizeof(XSavePKRU) },
+ [XSTATE_CET_U_BIT] = {
+ .feature = FEAT_7_0_ECX, .bits = CPUID_7_0_ECX_CET_SHSTK,
+ /*
+ * The features enabled in XSS MSR always use compacted format
+ * to store the data, in this case .offset == 0. And CET bits
+ * fall into this category.
+ */
+ .offset = 0,
+ .size = sizeof(XSavesCETU) },
+ [XSTATE_CET_S_BIT] = {
+ .feature = FEAT_7_0_ECX, .bits = CPUID_7_0_ECX_CET_SHSTK,
+ .offset = 0,
+ .size = sizeof(XSavesCETS) },
};
static uint32_t xsave_area_size(uint64_t mask, bool compacted)
@@ -6486,6 +6509,23 @@ static void x86_cpu_enable_xsave_components(X86CPU *cpu)
if (env->features[esa->feature] & esa->bits) {
mask |= (1ULL << i);
}
+
+ /*
+ * Both CET SHSTK and IBT feature requires XSAVES support, but two
+ * features can be controlled independently by kernel, and we only
+ * have one correlated bit set in x86_ext_save_areas, so if either
+ * of two features is enabled, we set the XSAVES support bit to make
+ * the enabled feature work.
+ */
+ if (i == XSTATE_CET_U_BIT || i == XSTATE_CET_S_BIT) {
+ uint64_t ecx = env->features[FEAT_7_0_ECX];
+ uint64_t edx = env->features[FEAT_7_0_EDX];
+
+ if ((ecx & CPUID_7_0_ECX_CET_SHSTK) ||
+ (edx & CPUID_7_0_EDX_CET_IBT)) {
+ mask |= (1ULL << i);
+ }
+ }
}
env->features[FEAT_XSAVE_XCR0_LO] = mask & CPUID_XSTATE_XCR0_MASK;
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index 42f835d455..593a2d6823 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -492,6 +492,8 @@ typedef enum X86Seg {
#define XSTATE_ZMM_Hi256_BIT 6
#define XSTATE_Hi16_ZMM_BIT 7
#define XSTATE_PKRU_BIT 9
+#define XSTATE_CET_U_BIT 11
+#define XSTATE_CET_S_BIT 12
#define XSTATE_FP_MASK (1ULL << XSTATE_FP_BIT)
#define XSTATE_SSE_MASK (1ULL << XSTATE_SSE_BIT)
@@ -502,6 +504,8 @@ typedef enum X86Seg {
#define XSTATE_ZMM_Hi256_MASK (1ULL << XSTATE_ZMM_Hi256_BIT)
#define XSTATE_Hi16_ZMM_MASK (1ULL << XSTATE_Hi16_ZMM_BIT)
#define XSTATE_PKRU_MASK (1ULL << XSTATE_PKRU_BIT)
+#define XSTATE_CET_U_MASK (1ULL << XSTATE_CET_U_BIT)
+#define XSTATE_CET_S_MASK (1ULL << XSTATE_CET_S_BIT)
/* CPUID feature bits available in XCR0 */
#define CPUID_XSTATE_XCR0_MASK (XSTATE_FP_MASK | XSTATE_SSE_MASK | \
@@ -761,6 +765,8 @@ typedef uint64_t FeatureWordArray[FEATURE_WORDS];
#define CPUID_7_0_ECX_WAITPKG (1U << 5)
/* Additional AVX-512 Vector Byte Manipulation Instruction */
#define CPUID_7_0_ECX_AVX512_VBMI2 (1U << 6)
+/* CET SHSTK feature */
+#define CPUID_7_0_ECX_CET_SHSTK (1U << 7)
/* Galois Field New Instructions */
#define CPUID_7_0_ECX_GFNI (1U << 8)
/* Vector AES Instructions */
@@ -800,6 +806,8 @@ typedef uint64_t FeatureWordArray[FEATURE_WORDS];
#define CPUID_7_0_EDX_SERIALIZE (1U << 14)
/* TSX Suspend Load Address Tracking instruction */
#define CPUID_7_0_EDX_TSX_LDTRK (1U << 16)
+/* CET IBT feature */
+#define CPUID_7_0_EDX_CET_IBT (1U << 20)
/* AVX512_FP16 instruction */
#define CPUID_7_0_EDX_AVX512_FP16 (1U << 23)
/* Speculation Control */
@@ -1301,6 +1309,19 @@ typedef struct XSavePKRU {
uint32_t padding;
} XSavePKRU;
+/* Ext. save area 11: User mode CET state */
+typedef struct XSavesCETU {
+ uint64_t u_cet;
+ uint64_t user_ssp;
+} XSavesCETU;
+
+/* Ext. save area 12: Supervisor mode CET state */
+typedef struct XSavesCETS {
+ uint64_t kernel_ssp;
+ uint64_t pl1_ssp;
+ uint64_t pl2_ssp;
+} XSavesCETS;
+
typedef struct X86XSaveArea {
X86LegacyXSaveArea legacy;
X86XSaveHeader header;
--
2.26.2
