i386: Introduce SnowRidge CPU model

SnowRidge CPU supports Accelerator Infrastrcture Architecture (MOVDIRI,
MOVDIR64B), CLDEMOTE and SPLIT_LOCK_DISABLE.

MOVDIRI, MOVDIR64B, and CLDEMOTE are found via CPUID.
The availability of SPLIT_LOCK_DISABLE is check via msr access

References can be found in either:
https://software.intel.com/en-us/articles/intel-sdm
https://software.intel.com/en-us/download/intel-architecture-instruction-set-extensions-and-future-features-programming-reference

Backports commit 0b18874bd216f3237740d5cbd64f39cf1e02addf from qemu

qemu/target/i386/cpu.c

@@ -2801,6 +2801,77 @@ static X86CPUDefinition builtin_x86_defs[] = {
         .xlevel = 0x80000008,
         .model_id = "Intel Xeon Processor (Icelake)",
     },
+    {
+        .name = "SnowRidge-Server",
+        .level = 27,
+        .vendor = CPUID_VENDOR_INTEL,
+        .family = 6,
+        .model = 134,
+        .stepping = 1,
+        .features[FEAT_1_EDX] =
+            /* missing: CPUID_PN CPUID_IA64 */
+            /* missing: CPUID_DTS, CPUID_HT, CPUID_TM, CPUID_PBE */
+            CPUID_FP87 | CPUID_VME | CPUID_DE | CPUID_PSE |
+            CPUID_TSC | CPUID_MSR | CPUID_PAE | CPUID_MCE |
+            CPUID_CX8 | CPUID_APIC | CPUID_SEP |
+            CPUID_MTRR | CPUID_PGE | CPUID_MCA | CPUID_CMOV |
+            CPUID_PAT | CPUID_PSE36 | CPUID_CLFLUSH |
+            CPUID_MMX |
+            CPUID_FXSR | CPUID_SSE | CPUID_SSE2,
+        .features[FEAT_1_ECX] =
+            CPUID_EXT_SSE3 | CPUID_EXT_PCLMULQDQ | CPUID_EXT_MONITOR |
+            CPUID_EXT_VMX |
+            CPUID_EXT_SSSE3 |
+            CPUID_EXT_CX16 |
+            CPUID_EXT_SSE41 |
+            CPUID_EXT_SSE42 | CPUID_EXT_X2APIC | CPUID_EXT_MOVBE |
+            CPUID_EXT_POPCNT |
+            CPUID_EXT_TSC_DEADLINE_TIMER | CPUID_EXT_AES | CPUID_EXT_XSAVE |
+            CPUID_EXT_RDRAND,
+        .features[FEAT_8000_0001_EDX] =
+            CPUID_EXT2_SYSCALL |
+            CPUID_EXT2_NX |
+            CPUID_EXT2_PDPE1GB | CPUID_EXT2_RDTSCP |
+            CPUID_EXT2_LM,
+        .features[FEAT_8000_0001_ECX] =
+            CPUID_EXT3_LAHF_LM |
+            CPUID_EXT3_3DNOWPREFETCH,
+        .features[FEAT_7_0_EBX] =
+            CPUID_7_0_EBX_FSGSBASE |
+            CPUID_7_0_EBX_SMEP |
+            CPUID_7_0_EBX_ERMS |
+            CPUID_7_0_EBX_MPX |  /* missing bits 13, 15 */
+            CPUID_7_0_EBX_RDSEED |
+            CPUID_7_0_EBX_SMAP | CPUID_7_0_EBX_CLFLUSHOPT |
+            CPUID_7_0_EBX_CLWB |
+            CPUID_7_0_EBX_SHA_NI,
+        .features[FEAT_7_0_ECX] =
+            CPUID_7_0_ECX_UMIP |
+            /* missing bit 5 */
+            CPUID_7_0_ECX_GFNI |
+            CPUID_7_0_ECX_MOVDIRI | CPUID_7_0_ECX_CLDEMOTE |
+            CPUID_7_0_ECX_MOVDIR64B,
+        .features[FEAT_7_0_EDX] =
+            CPUID_7_0_EDX_SPEC_CTRL |
+            CPUID_7_0_EDX_ARCH_CAPABILITIES | CPUID_7_0_EDX_SPEC_CTRL_SSBD |
+            CPUID_7_0_EDX_CORE_CAPABILITY,
+        .features[FEAT_CORE_CAPABILITY] =
+            MSR_CORE_CAP_SPLIT_LOCK_DETECT,
+        /*
+         * Missing: XSAVES (not supported by some Linux versions,
+         * including v4.1 to v4.12).
+         * KVM doesn't yet expose any XSAVES state save component,
+         * and the only one defined in Skylake (processor tracing)
+         * probably will block migration anyway.
+         */
+        .features[FEAT_XSAVE] =
+            CPUID_XSAVE_XSAVEOPT | CPUID_XSAVE_XSAVEC |
+            CPUID_XSAVE_XGETBV1,
+        .features[FEAT_6_EAX] =
+            CPUID_6_EAX_ARAT,
+        .xlevel = 0x80000008,
+        .model_id = "Intel Atom Processor (SnowRidge)",
+    },
     {
         .name = "KnightsMill",
         .level = 0xd,