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RE: [PATCH v1 1/3] i386: Remove the limitation of IP payloads for Intel
From: |
Kang, Luwei |
Subject: |
RE: [PATCH v1 1/3] i386: Remove the limitation of IP payloads for Intel PT |
Date: |
Tue, 29 Sep 2020 02:28:53 +0000 |
> >> No, if a feature cannot be emulated, that means it cannot be enabled
> >> unless it matches the host. That's generally not a problem since
> >> Intel PT is usually used only with "-cpu host".
> >>
> > The limitation of LIP in qemu will mask off the Intel PT in KVM guest
> > even with "-cpu host". e.g. This bit will be set in SnowRidge HW and
> > later.
>
> I agree that QEMU would have to learn about LIP. Unlike this patch, however,
> x86_cpu_filter_features would have to fail if host LIP != guest LIP. That is,
> something like
>
> (ecx_0 & INTEL_PT_IP_LIP)) !=
> (env->features[INTEL_PT_ECX_0] & INTEL_PT_IP_LIP)
>
> where "intel-pt-lip" would be a feature in env->features[INTEL_PT_ECX_0].
Got it. Thanks.
Luwei Kang
>
> > How about "-cpu cpu_model, +intel-pt" use case? The current value of
> > Intel PT CPUID is a constant. Can we make the ICX CPUID as basic
> > inforation(LIP is 0) and using "+intel-pt-lip" to make Intel PT work
> > on the CPU which LIP is 1 on the host? As you mentioned before, Intel
> > PT cannot be enabled in guest unless it matches the host.
>
> Yes, this would work.
>
> Paolo
- Re: [PATCH v1 1/3] i386: Remove the limitation of IP payloads for Intel PT, (continued)
- Re: [PATCH v1 1/3] i386: Remove the limitation of IP payloads for Intel PT, Eduardo Habkost, 2020/09/25
- Re: [PATCH v1 1/3] i386: Remove the limitation of IP payloads for Intel PT, Paolo Bonzini, 2020/09/25
- Re: [PATCH v1 1/3] i386: Remove the limitation of IP payloads for Intel PT, Eduardo Habkost, 2020/09/25
- Re: [PATCH v1 1/3] i386: Remove the limitation of IP payloads for Intel PT, Paolo Bonzini, 2020/09/25
- RE: [PATCH v1 1/3] i386: Remove the limitation of IP payloads for Intel PT, Kang, Luwei, 2020/09/28
- Re: [PATCH v1 1/3] i386: Remove the limitation of IP payloads for Intel PT, Paolo Bonzini, 2020/09/28
- RE: [PATCH v1 1/3] i386: Remove the limitation of IP payloads for Intel PT, Kang, Luwei, 2020/09/28
- Re: [PATCH v1 1/3] i386: Remove the limitation of IP payloads for Intel PT, Eduardo Habkost, 2020/09/28
- RE: [PATCH v1 1/3] i386: Remove the limitation of IP payloads for Intel PT, Kang, Luwei, 2020/09/28
- Re: [PATCH v1 1/3] i386: Remove the limitation of IP payloads for Intel PT, Paolo Bonzini, 2020/09/28
- RE: [PATCH v1 1/3] i386: Remove the limitation of IP payloads for Intel PT,
Kang, Luwei <=