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RE: [PATCH 1/2] i386: Add missing cpu feature bits in EPYC model


From: Moger, Babu
Subject: RE: [PATCH 1/2] i386: Add missing cpu feature bits in EPYC model
Date: Wed, 6 Nov 2019 00:16:53 +0000


> -----Original Message-----
> From: Eduardo Habkost <address@hidden>
> Sent: Tuesday, November 5, 2019 3:43 PM
> To: Moger, Babu <address@hidden>
> Cc: address@hidden; address@hidden; address@hidden;
> address@hidden; address@hidden
> Subject: Re: [PATCH 1/2] i386: Add missing cpu feature bits in EPYC model
> 
> On Tue, Nov 05, 2019 at 09:17:30PM +0000, Moger, Babu wrote:
> > Adds the following missing CPUID bits:
> > perfctr-core : core performance counter extensions support. Enables the VM
> >                to use extended performance counter support. It enables six
> >                programmable counters instead of 4 counters.
> > clzero       : instruction zeroes out the 64 byte cache line specified in 
> > RAX.
> > xsaveerptr   : XSAVE, XSAVE, FXSAVEOPT, XSAVEC, XSAVES always save error
> >                pointers and FXRSTOR, XRSTOR, XRSTORS always restore error
> >                pointers.
> > ibpb         : Indirect Branch Prediction Barrie.
> > xsaves       : XSAVES, XRSTORS and IA32_XSS supported.
> >
> > Depends on:
> > 40bc47b08b6e ("kvm: x86: Enumerate support for CLZERO instruction")
> > 504ce1954fba ("KVM: x86: Expose XSAVEERPTR to the guest")
> > 52297436199d ("kvm: svm: Update svm_xsaves_supported")
> >
> > Signed-off-by: Babu Moger <address@hidden>
> > ---
> >  hw/i386/pc.c      |    8 +++++++-
> >  target/i386/cpu.c |   11 +++++------
> >  2 files changed, 12 insertions(+), 7 deletions(-)
> >
> > diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> > index 51b72439b4..a72fe1db31 100644
> > --- a/hw/i386/pc.c
> > +++ b/hw/i386/pc.c
> > @@ -105,7 +105,13 @@ struct hpet_fw_config hpet_cfg = {.count =
> UINT8_MAX};
> >  /* Physical Address of PVH entry point read from kernel ELF NOTE */
> >  static size_t pvh_start_addr;
> >
> > -GlobalProperty pc_compat_4_1[] = {};
> > +GlobalProperty pc_compat_4_1[] = {
> > +    { "EPYC" "-" TYPE_X86_CPU, "perfctr-core", "off" },
> > +    { "EPYC" "-" TYPE_X86_CPU, "clzero", "off" },
> > +    { "EPYC" "-" TYPE_X86_CPU, "xsaveerptr", "off" },
> > +    { "EPYC" "-" TYPE_X86_CPU, "ibpb", "off" },
> > +    { "EPYC" "-" TYPE_X86_CPU, "xsaves", "off" },
> > +};
> 
> machine-type-based CPU compatibility was now replaced by
> versioned CPU models.  Please use the X86CPUDefinition.versions
> field to add a new version of EPYC instead.

Ok. Did  you mean like this commit  below?
fd63c6d1a5f77d68 ("i386: Add Cascadelake-Server-v2 CPU model")

> 
> >  const size_t pc_compat_4_1_len = G_N_ELEMENTS(pc_compat_4_1);
> >
> >  GlobalProperty pc_compat_4_0[] = {};
> > diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> > index 07cf562d89..71233e6310 100644
> > --- a/target/i386/cpu.c
> > +++ b/target/i386/cpu.c
> > @@ -3110,19 +3110,18 @@ static X86CPUDefinition builtin_x86_defs[] = {
> >              CPUID_EXT3_OSVW | CPUID_EXT3_3DNOWPREFETCH |
> >              CPUID_EXT3_MISALIGNSSE | CPUID_EXT3_SSE4A | CPUID_EXT3_ABM
> |
> >              CPUID_EXT3_CR8LEG | CPUID_EXT3_SVM | CPUID_EXT3_LAHF_LM |
> > -            CPUID_EXT3_TOPOEXT,
> > +            CPUID_EXT3_TOPOEXT | CPUID_EXT3_PERFCORE,
> > +        .features[FEAT_8000_0008_EBX] =
> > +            CPUID_8000_0008_EBX_CLZERO |
> CPUID_8000_0008_EBX_XSAVEERPTR |
> > +            CPUID_8000_0008_EBX_IBPB,
> >          .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_RDSEED |
> >              CPUID_7_0_EBX_ADX | CPUID_7_0_EBX_SMAP |
> CPUID_7_0_EBX_CLFLUSHOPT |
> >              CPUID_7_0_EBX_SHA_NI,
> > -        /* Missing: XSAVES (not supported by some Linux versions,
> > -         * including v4.1 to v4.12).
> > -         * KVM doesn't yet expose any XSAVES state save component.
> > -         */
> >          .features[FEAT_XSAVE] =
> >              CPUID_XSAVE_XSAVEOPT | CPUID_XSAVE_XSAVEC |
> > -            CPUID_XSAVE_XGETBV1,
> > +            CPUID_XSAVE_XGETBV1 | CPUID_XSAVE_XSAVES,
> >          .features[FEAT_6_EAX] =
> >              CPUID_6_EAX_ARAT,
> >          .features[FEAT_SVM] =
> >
> 
> --
> Eduardo




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