Re: [Qemu-devel] [PATCH] i386: add KNM cpu model

["Daniel P. Berrangé" <berrange@redhat.com>]

On Wed, Mar 14, 2018 at 03:29:59PM +0800, Boqun Feng wrote:
> A new cpu model called "KNM" is added to model Knights Mill processors.

Why the obscure acryonym? Can't we just call it KnightsMill so it is
obvious what it is to everyone, as we've done for all other Intel
CPU model names in the past.

> Compared to "Skylake-Server" cpu model, the following features are
> added:
> 
> 	avx512_4vnniw avx512_4fmaps avx512pf avx512er avx512_vpopcntdq
> 
> and the following features are removed:
> 
> 	pcid invpcid clflushopt avx512dq avx512bw axv512cd clwb smap rtm
> 	mpx xsavec xgetbv1 hle

"pcid" was one of the features critical to mitigate performance
downside of the Meltdown bug fix in guests. Will Knights Mill have
a fix for Meltdown in hardware, to avoid the need for split table
pages and thus avoid the perf hit in guests ?

> 
> Signed-off-by: Boqun Feng <boqun.feng@intel.com>
> ---
>  target/i386/cpu.c | 42 ++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 42 insertions(+)
> 
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index 2c04645ceac9..215a9ee6026a 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -1795,6 +1795,48 @@ static X86CPUDefinition builtin_x86_defs[] = {
>          .xlevel = 0x80000008,
>          .model_id = "Intel Xeon Processor (Skylake, IBRS)",
>      },
> +    {
> +        .name = "KNM",
> +        .level = 0xd,
> +        .vendor = CPUID_VENDOR_INTEL,
> +        .family = 6,
> +        .model = 133,
> +        .stepping = 0,
> +        .features[FEAT_1_EDX] =
> +            CPUID_VME | CPUID_SS | CPUID_SSE2 | CPUID_SSE | CPUID_FXSR |
> +            CPUID_MMX | CPUID_CLFLUSH | CPUID_PSE36 | CPUID_PAT | CPUID_CMOV |
> +            CPUID_MCA | CPUID_PGE | CPUID_MTRR | CPUID_SEP | CPUID_APIC |
> +            CPUID_CX8 | CPUID_MCE | CPUID_PAE | CPUID_MSR | CPUID_TSC |
> +            CPUID_PSE | CPUID_DE | CPUID_FP87,
> +        .features[FEAT_1_ECX] =
> +            CPUID_EXT_AVX | CPUID_EXT_XSAVE | CPUID_EXT_AES |
> +            CPUID_EXT_POPCNT | CPUID_EXT_X2APIC | CPUID_EXT_SSE42 |
> +            CPUID_EXT_SSE41 | CPUID_EXT_CX16 | CPUID_EXT_SSSE3 |
> +            CPUID_EXT_PCLMULQDQ | CPUID_EXT_SSE3 |
> +            CPUID_EXT_TSC_DEADLINE_TIMER | CPUID_EXT_FMA | CPUID_EXT_MOVBE |
> +            CPUID_EXT_F16C | CPUID_EXT_RDRAND,
> +        .features[FEAT_8000_0001_EDX] =
> +            CPUID_EXT2_LM | CPUID_EXT2_PDPE1GB | CPUID_EXT2_RDTSCP |
> +            CPUID_EXT2_NX | CPUID_EXT2_SYSCALL,
> +        .features[FEAT_8000_0001_ECX] =
> +            CPUID_EXT3_ABM | CPUID_EXT3_LAHF_LM | CPUID_EXT3_3DNOWPREFETCH,
> +        .features[FEAT_7_0_EBX] =
> +            CPUID_7_0_EBX_FSGSBASE | CPUID_7_0_EBX_BMI1 | CPUID_7_0_EBX_AVX2 |
> +            CPUID_7_0_EBX_SMEP | CPUID_7_0_EBX_BMI2 | CPUID_7_0_EBX_ERMS |
> +            CPUID_7_0_EBX_RDSEED | CPUID_7_0_EBX_ADX | CPUID_7_0_EBX_AVX512F |
> +            CPUID_7_0_EBX_AVX512CD | CPUID_7_0_EBX_AVX512PF |
> +            CPUID_7_0_EBX_AVX512ER,
> +        .features[FEAT_7_0_ECX] =
> +            CPUID_7_0_ECX_AVX512_VPOPCNTDQ,
> +        .features[FEAT_7_0_EDX] =
> +            CPUID_7_0_EDX_AVX512_4VNNIW | CPUID_7_0_EDX_AVX512_4FMAPS,
> +        .features[FEAT_XSAVE] =
> +            CPUID_XSAVE_XSAVEOPT,
> +        .features[FEAT_6_EAX] =
> +            CPUID_6_EAX_ARAT,
> +        .xlevel = 0x80000008,
> +        .model_id = "Intel Xeon Phi Processor (Knights Mill)",
> +    },
>      {
>          .name = "Opteron_G1",
>          .level = 5,
> -- 
> 2.16.1
> 
> 

Regards,
Daniel
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