[Qemu-devel][PATCH v5 0/4] Enable CET support for guest

[Qemu-devel][PATCH v5 0/4] Enable CET support for guest

[Yang Weijiang]

Control-flow Enforcement Technology (CET) provides protection against 
return/jump-oriented programming (ROP/JOP). It includes two
sub-features: Shadow Stack(SHSTK) and Indirect Branch Tracking(IBT).
This patchset is to enable CET related CPUID report, XSAVES/XRSTORS
support and MSR access etc. for guest.

CET KVM patches:
https://lkml.kernel.org/r/20200506082110.25441-1-weijiang.yang@intel.com

CET kernel patches:
https://lkml.kernel.org/r/20200429220732.31602-1-yu-cheng.yu@intel.com

v5:
  - Checked CET states before access related MSRs.
  - Added new MSR MSR_KVM_GUEST_SSP for live-migration.
  - Refactored patches to make them more structured.

v4:
  - Added MSR read/write interface for PL1_SSP/PL2_SSP.
  - Removed CET structures from X86XSaveArea.
  - Cleared ebx in return of CPUID.(EAX=d, ECX=1).
 
v3:
  - Add CET MSR save/restore support for live-migration.
 
v2:
  - In CPUID.(EAX=d, ECX=1), set return ECX[n] = 0 if bit n corresponds
    to a bit in MSR_IA32_XSS.
  - In CPUID.(EAX=d, ECX=n), set return ECX = 1 if bit n corresponds
    to a bit in MSR_IA32_XSS.
  - Skip Supervisor mode xsave component when calculate User mode
    xave component size in xsave_area_size() and x86_cpu_reset().

Yang Weijiang (4):
  x86/cpu: Add CET CPUID/XSAVES flags and data structures
  x86/cpuid: Add XSAVES feature words and CET related state bits
  x86/cpuid: Add support for XSAVES dependent feature enumeration
  x86/cpu: Add user space access interface for CET MSRs

 target/i386/cpu.c     |  57 ++++++++++++++-
 target/i386/cpu.h     |  53 ++++++++++++++
 target/i386/kvm.c     |  73 +++++++++++++++++++
 target/i386/machine.c | 161 ++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 341 insertions(+), 3 deletions(-)

-- 
2.17.2

[Qemu-devel][PATCH v5 1/4] x86/cpu: Add CET CPUID/XSAVES flags and data structures

[Yang Weijiang]

CET feature SHSTK and IBT are enumerated via CPUID(EAX=0x7,0):ECX[bit 7]
and EDX[bit 20] respectively. Two CET bits (bit 11 and 12) are defined in
MSR_IA32_XSS to support XSAVES/XRSTORS. CPUID(EAX=0xd, 1):ECX[bit 11] and
ECX[bit 12] correspond to CET states in user and supervisor mode respectively.

Signed-off-by: Zhang Yi <yi.z.zhang@linux.intel.com>
Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
---
 target/i386/cpu.h | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index e818fc712a..ed03cd1760 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -489,6 +489,9 @@ typedef enum X86Seg {
 #define XSTATE_ZMM_Hi256_BIT            6
 #define XSTATE_Hi16_ZMM_BIT             7
 #define XSTATE_PKRU_BIT                 9
+#define XSTATE_RESERVED_BIT             10
+#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)
@@ -499,6 +502,19 @@ 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_RESERVED_MASK            (1ULL << XSTATE_RESERVED_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_USER_MASK  (XSTATE_FP_MASK | XSTATE_SSE_MASK | \
+                                 XSTATE_YMM_MASK | XSTATE_BNDREGS_MASK | \
+                                 XSTATE_BNDCSR_MASK | XSTATE_OPMASK_MASK | \
+                                 XSTATE_ZMM_Hi256_MASK | \
+                                 XSTATE_Hi16_ZMM_MASK | XSTATE_PKRU_MASK)
+
+/* CPUID feature bits available in XSS */
+#define CPUID_XSTATE_KERNEL_MASK    (XSTATE_CET_U_MASK)
 
 /* CPUID feature words */
 typedef enum FeatureWord {
@@ -536,6 +552,8 @@ typedef enum FeatureWord {
     FEAT_VMX_EPT_VPID_CAPS,
     FEAT_VMX_BASIC,
     FEAT_VMX_VMFUNC,
+    FEAT_XSAVES_LO,     /* CPUID[EAX=0xd,ECX=1].ECX */
+    FEAT_XSAVES_HI,     /* CPUID[EAX=0xd,ECX=1].EDX */
     FEATURE_WORDS,
 } FeatureWord;
 
@@ -743,6 +761,8 @@ 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 */
@@ -770,6 +790,8 @@ typedef uint64_t FeatureWordArray[FEATURE_WORDS];
 #define CPUID_7_0_EDX_AVX512_4VNNIW     (1U << 2)
 /* AVX512 Multiply Accumulation Single Precision */
 #define CPUID_7_0_EDX_AVX512_4FMAPS     (1U << 3)
+/* CET IBT feature */
+#define CPUID_7_0_EDX_CET_IBT           (1U << 20)
 /* Speculation Control */
 #define CPUID_7_0_EDX_SPEC_CTRL         (1U << 26)
 /* Single Thread Indirect Branch Predictors */
@@ -1260,6 +1282,19 @@ 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;
-- 
2.17.2

[Qemu-devel][PATCH v5 2/4] x86/cpuid: Add XSAVES feature words and CET related state bits

[Yang Weijiang]

CET SHSTK/IBT MSRs can be saved/restored with XSAVES/XRSTORS, but
currently the related feature words are not supported, so add the
new entries. XSAVES/RSTORS always use compacted storage format, which
means the supervisor states' offsets are always 0, ignore them while
calculating stardard format storage size.

Signed-off-by: Zhang Yi <yi.z.zhang@linux.intel.com>
Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
---
 target/i386/cpu.c | 38 ++++++++++++++++++++++++++++++++++++--
 1 file changed, 36 insertions(+), 2 deletions(-)

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 90ffc5f3b1..3174e05482 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -965,7 +965,7 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
         .type = CPUID_FEATURE_WORD,
         .feat_names = {
             NULL, "avx512vbmi", "umip", "pku",
-            NULL /* ospke */, "waitpkg", "avx512vbmi2", NULL,
+            NULL /* ospke */, "waitpkg", "avx512vbmi2", "shstk",
             "gfni", "vaes", "vpclmulqdq", "avx512vnni",
             "avx512bitalg", NULL, "avx512-vpopcntdq", NULL,
             "la57", NULL, NULL, NULL,
@@ -988,7 +988,7 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
             NULL, NULL, "md-clear", NULL,
             NULL, NULL, NULL, NULL,
             NULL, NULL, NULL /* pconfig */, NULL,
-            NULL, NULL, NULL, NULL,
+            "ibt", NULL, NULL, NULL,
             NULL, NULL, "spec-ctrl", "stibp",
             NULL, "arch-capabilities", "core-capability", "ssbd",
         },
@@ -1069,6 +1069,26 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
         },
         .tcg_features = TCG_XSAVE_FEATURES,
     },
+    /* Below are xsaves feature words */
+    [FEAT_XSAVES_LO] = {
+        .type = CPUID_FEATURE_WORD,
+        .cpuid = {
+            .eax = 0xD,
+            .needs_ecx = true,
+            .ecx = 1,
+            .reg = R_ECX,
+        },
+        .migratable_flags = XSTATE_CET_U_MASK,
+    },
+    [FEAT_XSAVES_HI] = {
+        .type = CPUID_FEATURE_WORD,
+        .cpuid = {
+            .eax = 0xD,
+            .needs_ecx = true,
+            .ecx = 1,
+            .reg = R_EDX
+        },
+    },
     [FEAT_6_EAX] = {
         .type = CPUID_FEATURE_WORD,
         .feat_names = {
@@ -1455,6 +1475,14 @@ 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,
+            .offset = 0 /*supervisor mode component, offset = 0 */,
+            .size = sizeof(XSavesCETU) },
+    [XSTATE_CET_S_BIT] = {
+            .feature = FEAT_7_0_ECX, .bits = CPUID_7_0_ECX_CET_SHSTK,
+            .offset = 0 /*supervisor mode component, offset = 0 */,
+            .size = sizeof(XSavesCETS) },
 };
 
 static uint32_t xsave_area_size(uint64_t mask)
@@ -1465,6 +1493,9 @@ static uint32_t xsave_area_size(uint64_t mask)
     for (i = 0; i < ARRAY_SIZE(x86_ext_save_areas); i++) {
         const ExtSaveArea *esa = &x86_ext_save_areas[i];
         if ((mask >> i) & 1) {
+            if (i >= 2 && !esa->offset) {
+                continue;
+            }
             ret = MAX(ret, esa->offset + esa->size);
         }
     }
@@ -6008,6 +6039,9 @@ static void x86_cpu_reset(DeviceState *dev)
     }
     for (i = 2; i < ARRAY_SIZE(x86_ext_save_areas); i++) {
         const ExtSaveArea *esa = &x86_ext_save_areas[i];
+        if (!esa->offset) {
+            continue;
+        }
         if (env->features[esa->feature] & esa->bits) {
             xcr0 |= 1ull << i;
         }
-- 
2.17.2

[Qemu-devel][PATCH v5 3/4] x86/cpuid: Add support for XSAVES dependent feature enumeration

[Yang Weijiang]

Currently XSAVES dependent features are not supported in CPUID enumeration,
update CPUID(0xD,n>=1) to enable it.

CET XSAVES related enumeration includes:
CPUID(0xD,1):ECX[bit 11]: user mode CET state, controls bit 11 in XSS.
CPUID(0xD,1):ECX[bit 12]: supervisor mode CET state, controls bit 12 in XSS.
CPUID(0xD,11): user mode CET state sub-leaf, reports the state size.
CPUID(0xD,12): supervisor mode CE state sub-leaf, reports the state size.

Signed-off-by: Zhang Yi <yi.z.zhang@linux.intel.com>
Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
---
 target/i386/cpu.c | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 3174e05482..881c84a3b3 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -1513,6 +1513,12 @@ static inline uint64_t x86_cpu_xsave_components(X86CPU *cpu)
            cpu->env.features[FEAT_XSAVE_COMP_LO];
 }
 
+static inline uint64_t x86_cpu_xsave_sv_components(X86CPU *cpu)
+{
+    return ((uint64_t)cpu->env.features[FEAT_XSAVES_HI]) << 32 |
+           cpu->env.features[FEAT_XSAVES_LO];
+}
+
 const char *get_register_name_32(unsigned int reg)
 {
     if (reg >= CPU_NB_REGS32) {
@@ -5722,13 +5728,22 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
              */
             *ebx = kvm_enabled() ? *ecx : xsave_area_size(env->xcr0);
         } else if (count == 1) {
+            /* ebx is updated in kvm.*/
             *eax = env->features[FEAT_XSAVE];
+            *ecx = env->features[FEAT_XSAVES_LO];
+            *edx = env->features[FEAT_XSAVES_HI];
         } else if (count < ARRAY_SIZE(x86_ext_save_areas)) {
             if ((x86_cpu_xsave_components(cpu) >> count) & 1) {
                 const ExtSaveArea *esa = &x86_ext_save_areas[count];
                 *eax = esa->size;
                 *ebx = esa->offset;
             }
+            if ((x86_cpu_xsave_sv_components(cpu) >> count) & 1) {
+                const ExtSaveArea *esa_sv = &x86_ext_save_areas[count];
+                *eax = esa_sv->size;
+                *ebx = 0;
+                *ecx = 1;
+            }
         }
         break;
     }
@@ -6280,8 +6295,10 @@ static void x86_cpu_enable_xsave_components(X86CPU *cpu)
         }
     }
 
-    env->features[FEAT_XSAVE_COMP_LO] = mask;
+    env->features[FEAT_XSAVE_COMP_LO] = mask & CPUID_XSTATE_USER_MASK;
     env->features[FEAT_XSAVE_COMP_HI] = mask >> 32;
+    env->features[FEAT_XSAVES_LO] = mask & CPUID_XSTATE_KERNEL_MASK;
+    env->features[FEAT_XSAVES_HI] = mask >> 32;
 }
 
 /***** Steps involved on loading and filtering CPUID data
-- 
2.17.2

[Qemu-devel][PATCH v5 4/4] x86/cpu: Add user space access interface for CET MSRs

[Yang Weijiang]

Added interface for CET MSR_IA32_{U,S}_CET, MSR_IA32_PL{0,1,2,3}_SSP,
MSR_IA32_INTR_SSP_TBL and MSR_KVM_GUEST_SSP save/restore. Check if
corresponding CET features are available before access the MSRs.

Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
---
 target/i386/cpu.h     |  18 +++++
 target/i386/kvm.c     |  73 +++++++++++++++++++
 target/i386/machine.c | 161 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 252 insertions(+)

diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index ed03cd1760..51577a04ca 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -480,6 +480,15 @@ typedef enum X86Seg {
 #define MSR_IA32_VMX_TRUE_ENTRY_CTLS     0x00000490
 #define MSR_IA32_VMX_VMFUNC             0x00000491
 
+#define MSR_IA32_U_CET                  0x6a0
+#define MSR_IA32_S_CET                  0x6a2
+#define MSR_IA32_PL0_SSP                0x6a4
+#define MSR_IA32_PL1_SSP                0x6a5
+#define MSR_IA32_PL2_SSP                0x6a6
+#define MSR_IA32_PL3_SSP                0x6a7
+#define MSR_IA32_SSP_TBL                0x6a8
+#define MSR_KVM_GUEST_SSP               0x4b564d06
+
 #define XSTATE_FP_BIT                   0
 #define XSTATE_SSE_BIT                  1
 #define XSTATE_YMM_BIT                  2
@@ -1567,6 +1576,15 @@ typedef struct CPUX86State {
 
     uintptr_t retaddr;
 
+    uint64_t u_cet;
+    uint64_t s_cet;
+    uint64_t pl0_ssp;
+    uint64_t pl1_ssp;
+    uint64_t pl2_ssp;
+    uint64_t pl3_ssp;
+    uint64_t ssp_tbl;
+    uint64_t guest_ssp;
+
     /* Fields up to this point are cleared by a CPU reset */
     struct {} end_reset_fields;
 
diff --git a/target/i386/kvm.c b/target/i386/kvm.c
index 4901c6dd74..0735981558 100644
--- a/target/i386/kvm.c
+++ b/target/i386/kvm.c
@@ -2979,6 +2979,31 @@ static int kvm_put_msrs(X86CPU *cpu, int level)
         }
     }
 
+    if (((env->features[FEAT_7_0_ECX] & CPUID_7_0_ECX_CET_SHSTK) ||
+        (env->features[FEAT_7_0_EDX] & CPUID_7_0_EDX_CET_IBT)) &&
+        (env->features[FEAT_XSAVES_LO] & XSTATE_CET_U_MASK)) {
+        kvm_msr_entry_add(cpu, MSR_IA32_U_CET, env->u_cet);
+        kvm_msr_entry_add(cpu, MSR_IA32_PL3_SSP, env->pl3_ssp);
+    }
+
+    if (env->features[FEAT_XSAVES_LO] & XSTATE_CET_S_MASK) {
+        if (env->features[FEAT_7_0_ECX] & CPUID_7_0_ECX_CET_SHSTK) {
+            kvm_msr_entry_add(cpu, MSR_IA32_PL0_SSP, env->pl0_ssp);
+            kvm_msr_entry_add(cpu, MSR_IA32_PL1_SSP, env->pl1_ssp);
+            kvm_msr_entry_add(cpu, MSR_IA32_PL2_SSP, env->pl2_ssp);
+            kvm_msr_entry_add(cpu, MSR_IA32_SSP_TBL, env->ssp_tbl);
+        }
+
+        if (env->features[FEAT_7_0_EDX] & CPUID_7_0_EDX_CET_IBT) {
+            kvm_msr_entry_add(cpu, MSR_IA32_S_CET, env->s_cet);
+        }
+    }
+
+    if ((env->features[FEAT_7_0_ECX] & CPUID_7_0_ECX_CET_SHSTK) &&
+        (env->features[FEAT_XSAVES_LO] & (XSTATE_CET_U_MASK |
+        XSTATE_CET_S_MASK)))
+        kvm_msr_entry_add(cpu, MSR_KVM_GUEST_SSP, env->guest_ssp);
+
     return kvm_buf_set_msrs(cpu);
 }
 
@@ -3295,6 +3320,30 @@ static int kvm_get_msrs(X86CPU *cpu)
         }
     }
 
+    if (((env->features[FEAT_7_0_ECX] & CPUID_7_0_ECX_CET_SHSTK) ||
+        (env->features[FEAT_7_0_EDX] & CPUID_7_0_EDX_CET_IBT)) &&
+        (env->features[FEAT_XSAVES_LO] & XSTATE_CET_U_MASK)) {
+        kvm_msr_entry_add(cpu, MSR_IA32_U_CET, 0);
+        kvm_msr_entry_add(cpu, MSR_IA32_PL3_SSP, 0);
+    }
+
+    if (env->features[FEAT_XSAVES_LO] & XSTATE_CET_S_MASK) {
+        if (env->features[FEAT_7_0_ECX] & CPUID_7_0_ECX_CET_SHSTK) {
+            kvm_msr_entry_add(cpu, MSR_IA32_PL0_SSP, 0);
+            kvm_msr_entry_add(cpu, MSR_IA32_PL1_SSP, 0);
+            kvm_msr_entry_add(cpu, MSR_IA32_PL2_SSP, 0);
+            kvm_msr_entry_add(cpu, MSR_IA32_SSP_TBL, 0);
+        }
+
+        if (env->features[FEAT_7_0_EDX] & CPUID_7_0_EDX_CET_IBT) {
+            kvm_msr_entry_add(cpu, MSR_IA32_S_CET, 0);
+        }
+    }
+    if ((env->features[FEAT_7_0_ECX] & CPUID_7_0_ECX_CET_SHSTK) &&
+        (env->features[FEAT_XSAVES_LO] & (XSTATE_CET_U_MASK |
+        XSTATE_CET_S_MASK)))
+        kvm_msr_entry_add(cpu, MSR_KVM_GUEST_SSP, 0);
+
     ret = kvm_vcpu_ioctl(CPU(cpu), KVM_GET_MSRS, cpu->kvm_msr_buf);
     if (ret < 0) {
         return ret;
@@ -3578,6 +3627,30 @@ static int kvm_get_msrs(X86CPU *cpu)
         case MSR_IA32_RTIT_ADDR0_A ... MSR_IA32_RTIT_ADDR3_B:
             env->msr_rtit_addrs[index - MSR_IA32_RTIT_ADDR0_A] = msrs[i].data;
             break;
+        case MSR_IA32_U_CET:
+            env->u_cet = msrs[i].data;
+            break;
+        case MSR_IA32_S_CET:
+            env->s_cet = msrs[i].data;
+            break;
+        case MSR_IA32_PL0_SSP:
+            env->pl0_ssp = msrs[i].data;
+            break;
+        case MSR_IA32_PL1_SSP:
+            env->pl1_ssp = msrs[i].data;
+            break;
+        case MSR_IA32_PL2_SSP:
+            env->pl2_ssp = msrs[i].data;
+            break;
+        case MSR_IA32_PL3_SSP:
+            env->pl3_ssp = msrs[i].data;
+            break;
+        case MSR_IA32_SSP_TBL:
+            env->ssp_tbl = msrs[i].data;
+            break;
+        case MSR_KVM_GUEST_SSP:
+            env->guest_ssp = msrs[i].data;
+            break;
         }
     }
 
diff --git a/target/i386/machine.c b/target/i386/machine.c
index 0c96531a56..3e1d8b6eb9 100644
--- a/target/i386/machine.c
+++ b/target/i386/machine.c
@@ -962,6 +962,159 @@ static const VMStateDescription vmstate_umwait = {
     }
 };
 
+static bool u_cet_needed(void *opaque)
+{
+    X86CPU *cpu = opaque;
+    CPUX86State *env = &cpu->env;
+
+    return env->u_cet != 0;
+}
+
+static const VMStateDescription vmstate_u_cet = {
+    .name = "cpu/u_cet",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = u_cet_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT64(env.u_cet, X86CPU),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static bool s_cet_needed(void *opaque)
+{
+    X86CPU *cpu = opaque;
+    CPUX86State *env = &cpu->env;
+
+    return env->s_cet != 0;
+}
+
+static const VMStateDescription vmstate_s_cet = {
+    .name = "cpu/s_cet",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = s_cet_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT64(env.s_cet, X86CPU),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static bool pl0_ssp_needed(void *opaque)
+{
+    X86CPU *cpu = opaque;
+    CPUX86State *env = &cpu->env;
+
+    return env->pl0_ssp != 0;
+}
+
+static const VMStateDescription vmstate_pl0_ssp = {
+    .name = "cpu/pl0_ssp",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = pl0_ssp_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT64(env.pl0_ssp, X86CPU),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static bool pl1_ssp_needed(void *opaque)
+{
+    X86CPU *cpu = opaque;
+    CPUX86State *env = &cpu->env;
+
+    return env->pl1_ssp != 0;
+}
+
+static const VMStateDescription vmstate_pl1_ssp = {
+    .name = "cpu/pl1_ssp",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = pl1_ssp_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT64(env.pl1_ssp, X86CPU),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static bool pl2_ssp_needed(void *opaque)
+{
+    X86CPU *cpu = opaque;
+    CPUX86State *env = &cpu->env;
+
+    return env->pl2_ssp != 0;
+}
+
+static const VMStateDescription vmstate_pl2_ssp = {
+    .name = "cpu/pl2_ssp",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = pl2_ssp_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT64(env.pl2_ssp, X86CPU),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+
+static bool pl3_ssp_needed(void *opaque)
+{
+    X86CPU *cpu = opaque;
+    CPUX86State *env = &cpu->env;
+
+    return env->pl3_ssp != 0;
+}
+
+static const VMStateDescription vmstate_pl3_ssp = {
+    .name = "cpu/pl3_ssp",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = pl3_ssp_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT64(env.pl3_ssp, X86CPU),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static bool ssp_tbl_needed(void *opaque)
+{
+    X86CPU *cpu = opaque;
+    CPUX86State *env = &cpu->env;
+
+    return env->ssp_tbl != 0;
+}
+
+static const VMStateDescription vmstate_ssp_tbl = {
+    .name = "cpu/ssp_tbl",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = ssp_tbl_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT64(env.ssp_tbl, X86CPU),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static bool guest_ssp_needed(void *opaque)
+{
+    X86CPU *cpu = opaque;
+    CPUX86State *env = &cpu->env;
+
+    return env->guest_ssp != 0;
+}
+
+static const VMStateDescription vmstate_guest_ssp = {
+    .name = "cpu/guest_ssp",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = guest_ssp_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT64(env.guest_ssp, X86CPU),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 #ifdef TARGET_X86_64
 static bool pkru_needed(void *opaque)
 {
@@ -1447,6 +1600,14 @@ VMStateDescription vmstate_x86_cpu = {
         &vmstate_nested_state,
 #endif
         &vmstate_msr_tsx_ctrl,
+        &vmstate_u_cet,
+        &vmstate_s_cet,
+        &vmstate_pl0_ssp,
+        &vmstate_pl1_ssp,
+        &vmstate_pl2_ssp,
+        &vmstate_pl3_ssp,
+        &vmstate_ssp_tbl,
+        &vmstate_guest_ssp,
         NULL
     }
 };
-- 
2.17.2

Re: [Qemu-devel][PATCH v5 1/4] x86/cpu: Add CET CPUID/XSAVES flags and data structures

[Xiaoyao Li]

On 5/10/2020 9:42 AM, Yang Weijiang wrote:
> CET feature SHSTK and IBT are enumerated via CPUID(EAX=0x7,0):ECX[bit 7]
> and EDX[bit 20] respectively. Two CET bits (bit 11 and 12) are defined in
> MSR_IA32_XSS to support XSAVES/XRSTORS. CPUID(EAX=0xd, 1):ECX[bit 11] and
> ECX[bit 12] correspond to CET states in user and supervisor mode respectively.
> 
> Signed-off-by: Zhang Yi <yi.z.zhang@linux.intel.com>
> Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
> ---
>   target/i386/cpu.h | 35 +++++++++++++++++++++++++++++++++++
>   1 file changed, 35 insertions(+)
> 
> diff --git a/target/i386/cpu.h b/target/i386/cpu.h
> index e818fc712a..ed03cd1760 100644
> --- a/target/i386/cpu.h
> +++ b/target/i386/cpu.h
> @@ -489,6 +489,9 @@ typedef enum X86Seg {
>   #define XSTATE_ZMM_Hi256_BIT            6
>   #define XSTATE_Hi16_ZMM_BIT             7
>   #define XSTATE_PKRU_BIT                 9
> +#define XSTATE_RESERVED_BIT             10

I think this is unnecessary. bit 8 and so many other undefined bits are 
reserved too.

> +#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)
> @@ -499,6 +502,19 @@ 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_RESERVED_MASK            (1ULL << XSTATE_RESERVED_BIT)

Ditto.

> +#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_USER_MASK  (XSTATE_FP_MASK | XSTATE_SSE_MASK | \
> +                                 XSTATE_YMM_MASK | XSTATE_BNDREGS_MASK | \
> +                                 XSTATE_BNDCSR_MASK | XSTATE_OPMASK_MASK | \
> +                                 XSTATE_ZMM_Hi256_MASK | \
> +                                 XSTATE_Hi16_ZMM_MASK | XSTATE_PKRU_MASK)
> +
> +/* CPUID feature bits available in XSS */
> +#define CPUID_XSTATE_KERNEL_MASK    (XSTATE_CET_U_MASK)

How about we name it XSTATE_XCR0_MASK and XSTATE_XSS_MASK.

They are not CPUID feature bit, at least the CPUID_ prefix needs to be 
removed.

>   
>   /* CPUID feature words */
>   typedef enum FeatureWord {
> @@ -536,6 +552,8 @@ typedef enum FeatureWord {
>       FEAT_VMX_EPT_VPID_CAPS,
>       FEAT_VMX_BASIC,
>       FEAT_VMX_VMFUNC,
> +    FEAT_XSAVES_LO,     /* CPUID[EAX=0xd,ECX=1].ECX */
> +    FEAT_XSAVES_HI,     /* CPUID[EAX=0xd,ECX=1].EDX */

I don't think *XSAVES* is a good name, because XSAVES and manipulate the 
features masked by XCR0 | MSR_IA32_XSS. But this CPUID leaf only 
enumerated XSTATE features for XSS.

How about name it FEAT_XSS_LO/HI? or FEAT_XSAVES_XSS_HO/HI

>       FEATURE_WORDS,
>   } FeatureWord;
>   
> @@ -743,6 +761,8 @@ 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 */
> @@ -770,6 +790,8 @@ typedef uint64_t FeatureWordArray[FEATURE_WORDS];
>   #define CPUID_7_0_EDX_AVX512_4VNNIW     (1U << 2)
>   /* AVX512 Multiply Accumulation Single Precision */
>   #define CPUID_7_0_EDX_AVX512_4FMAPS     (1U << 3)
> +/* CET IBT feature */
> +#define CPUID_7_0_EDX_CET_IBT           (1U << 20)
>   /* Speculation Control */
>   #define CPUID_7_0_EDX_SPEC_CTRL         (1U << 26)
>   /* Single Thread Indirect Branch Predictors */
> @@ -1260,6 +1282,19 @@ 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;
> 

Re: [Qemu-devel][PATCH v5 2/4] x86/cpuid: Add XSAVES feature words and CET related state bits

[Xiaoyao Li]

On 5/10/2020 9:42 AM, Yang Weijiang wrote:
> CET SHSTK/IBT MSRs can be saved/restored with XSAVES/XRSTORS, but
> currently the related feature words are not supported, so add the
> new entries. XSAVES/RSTORS always use compacted storage format, which
> means the supervisor states' offsets are always 0, ignore them while
> calculating stardard format storage size.
> 
> Signed-off-by: Zhang Yi <yi.z.zhang@linux.intel.com>
> Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
> ---
>   target/i386/cpu.c | 38 ++++++++++++++++++++++++++++++++++++--
>   1 file changed, 36 insertions(+), 2 deletions(-)
> 
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index 90ffc5f3b1..3174e05482 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -965,7 +965,7 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
>           .type = CPUID_FEATURE_WORD,
>           .feat_names = {
>               NULL, "avx512vbmi", "umip", "pku",
> -            NULL /* ospke */, "waitpkg", "avx512vbmi2", NULL,
> +            NULL /* ospke */, "waitpkg", "avx512vbmi2", "shstk",
>               "gfni", "vaes", "vpclmulqdq", "avx512vnni",
>               "avx512bitalg", NULL, "avx512-vpopcntdq", NULL,
>               "la57", NULL, NULL, NULL,
> @@ -988,7 +988,7 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
>               NULL, NULL, "md-clear", NULL,
>               NULL, NULL, NULL, NULL,
>               NULL, NULL, NULL /* pconfig */, NULL,
> -            NULL, NULL, NULL, NULL,
> +            "ibt", NULL, NULL, NULL,
>               NULL, NULL, "spec-ctrl", "stibp",
>               NULL, "arch-capabilities", "core-capability", "ssbd",
>           },
> @@ -1069,6 +1069,26 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
>           },
>           .tcg_features = TCG_XSAVE_FEATURES,
>       },
> +    /* Below are xsaves feature words */
> +    [FEAT_XSAVES_LO] = {
> +        .type = CPUID_FEATURE_WORD,
> +        .cpuid = {
> +            .eax = 0xD,
> +            .needs_ecx = true,
> +            .ecx = 1,
> +            .reg = R_ECX,
> +        },
> +        .migratable_flags = XSTATE_CET_U_MASK,

why exclude XSTATE_CET_S_MASK? Is any reason why it not migratable?

> +    },
> +    [FEAT_XSAVES_HI] = {
> +        .type = CPUID_FEATURE_WORD,
> +        .cpuid = {
> +            .eax = 0xD,
> +            .needs_ecx = true,
> +            .ecx = 1,
> +            .reg = R_EDX
> +        },
> +    },
>       [FEAT_6_EAX] = {
>           .type = CPUID_FEATURE_WORD,
>           .feat_names = {
> @@ -1455,6 +1475,14 @@ 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,
> +            .offset = 0 /*supervisor mode component, offset = 0 */,
> +            .size = sizeof(XSavesCETU) },
> +    [XSTATE_CET_S_BIT] = {
> +            .feature = FEAT_7_0_ECX, .bits = CPUID_7_0_ECX_CET_SHSTK,
> +            .offset = 0 /*supervisor mode component, offset = 0 */,
> +            .size = sizeof(XSavesCETS) },
>   };
>   
>   static uint32_t xsave_area_size(uint64_t mask)
> @@ -1465,6 +1493,9 @@ static uint32_t xsave_area_size(uint64_t mask)
>       for (i = 0; i < ARRAY_SIZE(x86_ext_save_areas); i++) {
>           const ExtSaveArea *esa = &x86_ext_save_areas[i];
>           if ((mask >> i) & 1) {
> +            if (i >= 2 && !esa->offset) {
> +                continue;
> +            }
>               ret = MAX(ret, esa->offset + esa->size);
>           }
>       }
> @@ -6008,6 +6039,9 @@ static void x86_cpu_reset(DeviceState *dev)
>       }
>       for (i = 2; i < ARRAY_SIZE(x86_ext_save_areas); i++) {
>           const ExtSaveArea *esa = &x86_ext_save_areas[i];
> +        if (!esa->offset) {
> +            continue;
> +        }
>           if (env->features[esa->feature] & esa->bits) {
>               xcr0 |= 1ull << i;
>           }
>