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From: "Kang, Luwei" <luwei.kang@intel.com>
To: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"tglx@linutronix.de" <tglx@linutronix.de>,
	"mingo@redhat.com" <mingo@redhat.com>,
	"hpa@zytor.com" <hpa@zytor.com>,
	"x86@kernel.org" <x86@kernel.org>,
	"chao.p.peng@linux.intel.com" <chao.p.peng@linux.intel.com>,
	"thomas.lendacky@amd.com" <thomas.lendacky@amd.com>,
	"bp@suse.de" <bp@suse.de>, "Liang, Kan" <kan.liang@intel.com>,
	"Janakarajan.Natarajan@amd.com" <Janakarajan.Natarajan@amd.com>,
	"dwmw@amazon.co.uk" <dwmw@amazon.co.uk>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"peterz@infradead.org" <peterz@infradead.org>,
	"mathieu.poirier@linaro.org" <mathieu.poirier@linaro.org>,
	"kstewart@linuxfoundation.org" <kstewart@linuxfoundation.org>,
	"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	"pbonzini@redhat.com" <pbonzini@redhat.com>,
	"rkrcmar@redhat.com" <rkrcmar@redhat.com>,
	"david@redhat.com" <david@redhat.com>,
	"bsd@redhat.com" <bsd@redhat.com>,
	"yu.c.zhang@linux.intel.com" <yu.c.zhang@linux.intel.com>,
	"joro@8bytes.org" <joro@8bytes.org>
Subject: RE: [PATCH v9 06/12] KVM: x86: Add Intel Processor Trace virtualization mode
Date: Fri, 8 Jun 2018 14:19:09 +0000	[thread overview]
Message-ID: <82D7661F83C1A047AF7DC287873BF1E167FEFF92@SHSMSX101.ccr.corp.intel.com> (raw)
In-Reply-To: <20180607132638.snnnt5ecwisfgkmy@um.fi.intel.com>

> > From: Chao Peng <chao.p.peng@linux.intel.com>
> >
> > Intel PT virtualization can be work in one of 2 possible modes:
> > a. system-wide: trace both host and guest and output to host buffer;
> > b. host-guest: trace host/guest simultaneous and output to their
> >    respective buffer.
> 
> I think we discussed this before. That's not the choice that the user needs to
> make. The only choice that I see is what happens if the guest wants to use PT
> while it's already in use by the host. Otherwise, each of them gets to use PT
> as they would.
> 

Hi,
    Thanks for your reply first. If guest want to use PT that we need to expose this feature to guest and guest will save these trace packets to guest buffer. Host will can't get the trace which are made by KVM guest. This is Host_Guest mode.
On the other hand,  host may also want to trace hypervisor and KVM guest execution trace and output these trace in native. This is SYSTEM mode. PT can't be exposed to guest in this mode or KVM guest trace will be lost in native buffer.
These are two different use case and can't coexist.

Thanks,
Luwei Kang

WARNING: multiple messages have this Message-ID (diff)
From: "Kang, Luwei" <luwei.kang@intel.com>
To: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"tglx@linutronix.de" <tglx@linutronix.de>,
	"mingo@redhat.com" <mingo@redhat.com>,
	"hpa@zytor.com" <hpa@zytor.com>,
	"x86@kernel.org" <x86@kernel.org>,
	"chao.p.peng@linux.intel.com" <chao.p.peng@linux.intel.com>,
	"thomas.lendacky@amd.com" <thomas.lendacky@amd.com>,
	"bp@suse.de" <bp@suse.de>, "Liang, Kan" <kan.liang@intel.com>,
	"Janakarajan.Natarajan@amd.com" <Janakarajan.Natarajan@amd.com>,
	"dwmw@amazon.co.uk" <dwmw@amazon.co.uk>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"peterz@infradead.org" <peterz@infradead.org>,
	"mathieu.poirier@linaro.org" <mathieu.poirier@linaro.org>,
	"kstewart@linuxfoundation.org" <kstewart@linuxfoundation.org>,
	"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	"pbonzini@redha
Subject: RE: [PATCH v9 06/12] KVM: x86: Add Intel Processor Trace virtualization mode
Date: Fri, 8 Jun 2018 14:19:09 +0000	[thread overview]
Message-ID: <82D7661F83C1A047AF7DC287873BF1E167FEFF92@SHSMSX101.ccr.corp.intel.com> (raw)
In-Reply-To: <20180607132638.snnnt5ecwisfgkmy@um.fi.intel.com>

> > From: Chao Peng <chao.p.peng@linux.intel.com>
> >
> > Intel PT virtualization can be work in one of 2 possible modes:
> > a. system-wide: trace both host and guest and output to host buffer;
> > b. host-guest: trace host/guest simultaneous and output to their
> >    respective buffer.
> 
> I think we discussed this before. That's not the choice that the user needs to
> make. The only choice that I see is what happens if the guest wants to use PT
> while it's already in use by the host. Otherwise, each of them gets to use PT
> as they would.
> 

Hi,
    Thanks for your reply first. If guest want to use PT that we need to expose this feature to guest and guest will save these trace packets to guest buffer. Host will can't get the trace which are made by KVM guest. This is Host_Guest mode.
On the other hand,  host may also want to trace hypervisor and KVM guest execution trace and output these trace in native. This is SYSTEM mode. PT can't be exposed to guest in this mode or KVM guest trace will be lost in native buffer.
These are two different use case and can't coexist.

Thanks,
Luwei Kang

  reply	other threads:[~2018-06-08 14:19 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-22  4:52 [PATCH v9 00/12] Intel Processor Trace virtualization enabling Luwei Kang
2018-05-22  4:52 ` [PATCH v9 01/12] perf/x86/intel/pt: Move Intel-PT MSRs bit definitions to a public header Luwei Kang
2018-06-07  6:50   ` Kang, Luwei
2018-06-07 11:21     ` Paolo Bonzini
2018-05-22  4:52 ` [PATCH v9 02/12] perf/x86/intel/pt: Change pt_cap_get() to a public function Luwei Kang
2018-05-22  4:52 ` [PATCH v9 03/12] perf/x86/intel/pt: Add new bit definitions for Intel PT MSRs Luwei Kang
2018-06-07 13:33   ` Alexander Shishkin
2018-06-08 14:26     ` Kang, Luwei
2018-06-08 14:26       ` Kang, Luwei
2018-05-22  4:52 ` [PATCH v9 04/12] perf/x86/intel/pt: add new capability for Intel PT Luwei Kang
2018-06-07 13:40   ` Alexander Shishkin
2018-06-07 13:51     ` Peter Zijlstra
2018-06-08 14:37       ` Kang, Luwei
2018-06-08 14:37         ` Kang, Luwei
2018-06-08 14:34     ` Kang, Luwei
2018-06-08 14:34       ` Kang, Luwei
2018-05-22  4:52 ` [PATCH v9 05/12] perf/x86/intel/pt: Introduce a new function to get capability of " Luwei Kang
2018-05-22  4:52 ` [PATCH v9 06/12] KVM: x86: Add Intel Processor Trace virtualization mode Luwei Kang
2018-06-07 13:26   ` Alexander Shishkin
2018-06-08 14:19     ` Kang, Luwei [this message]
2018-06-08 14:19       ` Kang, Luwei
2018-06-11 11:39     ` Paolo Bonzini
2018-05-22  4:52 ` [PATCH v9 07/12] KVM: x86: Add Intel Processor Trace cpuid emulation Luwei Kang
2018-05-22  4:52 ` [PATCH v9 08/12] KVM: x86: Add Intel Processor Trace context switch for each vcpu Luwei Kang
2018-05-22  4:52 ` [PATCH v9 09/12] KVM: x86: Introduce a function to initialize the PT configuration Luwei Kang
2018-06-07 13:56   ` Alexander Shishkin
2018-06-08 14:56     ` Kang, Luwei
2018-06-08 14:56       ` Kang, Luwei
2018-06-11 11:41       ` Paolo Bonzini
2018-06-11 11:41         ` Paolo Bonzini
2018-06-12  1:30         ` Kang, Luwei
2018-06-12  1:30           ` Kang, Luwei
2018-05-22  4:52 ` [PATCH v9 10/12] KVM: x86: Implement Intel Processor Trace MSRs read/write emulation Luwei Kang
2018-06-07 14:12   ` Alexander Shishkin
2018-06-08 15:12     ` Kang, Luwei
2018-06-08 15:12       ` Kang, Luwei
2018-05-22  4:52 ` [PATCH v9 11/12] KVM: x86: Set intercept for Intel PT MSRs read/write Luwei Kang
2018-06-07 14:22   ` Alexander Shishkin
2018-06-08 15:16     ` Kang, Luwei
2018-06-08 15:16       ` Kang, Luwei
2018-05-22  4:52 ` [PATCH v9 12/12] KVM: x86: Disable Intel Processor Trace when VMXON in L1 guest Luwei Kang

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