From: Andrew Cooper <andrew.cooper3@citrix.com>
To: "Julien Grall" <julien@xen.org>,
"Michał Leszczyński" <michal.leszczynski@cert.pl>,
xen-devel@lists.xenproject.org
Cc: "Kevin Tian" <kevin.tian@intel.com>,
"Stefano Stabellini" <sstabellini@kernel.org>,
tamas.lengyel@intel.com, "Jun Nakajima" <jun.nakajima@intel.com>,
"Wei Liu" <wl@xen.org>, "Ian Jackson" <ian.jackson@eu.citrix.com>,
"George Dunlap" <george.dunlap@citrix.com>,
"Jan Beulich" <jbeulich@suse.com>,
luwei.kang@intel.com, "Roger Pau Monné" <roger.pau@citrix.com>
Subject: Re: [PATCH v4 02/10] x86/vmx: add IPT cpu feature
Date: Wed, 1 Jul 2020 18:26:15 +0100 [thread overview]
Message-ID: <a7187837-495f-56a5-a8d0-635a53ac9234@citrix.com> (raw)
In-Reply-To: <a9a33ba1-b121-5e6f-b74c-7d2a60c84b13@xen.org>
On 01/07/2020 17:18, Julien Grall wrote:
>
>
> On 01/07/2020 17:17, Julien Grall wrote:
>>
>>
>> On 01/07/2020 17:06, Andrew Cooper wrote:
>>> On 01/07/2020 16:12, Julien Grall wrote:
>>>> On 30/06/2020 13:33, Michał Leszczyński wrote:
>>>>> @@ -305,7 +311,6 @@ static int vmx_init_vmcs_config(void)
>>>>> SECONDARY_EXEC_ENABLE_VIRT_EXCEPTIONS |
>>>>> SECONDARY_EXEC_XSAVES |
>>>>> SECONDARY_EXEC_TSC_SCALING);
>>>>> - rdmsrl(MSR_IA32_VMX_MISC, _vmx_misc_cap);
>>>>> if ( _vmx_misc_cap & VMX_MISC_VMWRITE_ALL )
>>>>> opt |= SECONDARY_EXEC_ENABLE_VMCS_SHADOWING;
>>>>> if ( opt_vpid_enabled )
>>>>> diff --git a/xen/common/domain.c b/xen/common/domain.c
>>>>> index 7cc9526139..0a33e0dfd6 100644
>>>>> --- a/xen/common/domain.c
>>>>> +++ b/xen/common/domain.c
>>>>> @@ -82,6 +82,8 @@ struct vcpu *idle_vcpu[NR_CPUS] __read_mostly;
>>>>> vcpu_info_t dummy_vcpu_info;
>>>>> +bool_t vmtrace_supported;
>>>>
>>>> All the code looks x86 specific. So may I ask why this was implemented
>>>> in common code?
>>>
>>> There were some questions directed specifically at the ARM maintainers
>>> about CoreSight, which have gone unanswered.
>>
>> I can only find one question related to the size. Is there any other?
>>
>> I don't know how the interface will look like given that AFAICT the
>> buffer may be embedded in the HW. We would need to investigate how to
>> differentiate between two domUs in this case without impacting the
>> performance in the common code.
>
> s/in the common code/during the context switch/
>
>> So I think it is a little premature to implement this in common code
>> and always compiled in for Arm. It would be best if this stay in x86
>> code.
I've just checked with a colleague. CoreSight can dump to a memory
buffer - there's even a decode library for the packet stream
https://github.com/Linaro/OpenCSD, although ultimately it is platform
specific as to whether the feature is supported.
Furthermore, the choice isn't "x86 vs ARM", now that RISCv support is
on-list, and Power9 is floating on the horizon.
For the sake of what is literally just one byte in common code, I stand
my original suggestion of this being a common interface. It is not
something which should be x86 specific.
~Andrew
next prev parent reply other threads:[~2020-07-01 17:27 UTC|newest]
Thread overview: 75+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-30 12:33 [PATCH v4 00/10] Implement support for external IPT monitoring Michał Leszczyński
2020-06-30 12:33 ` [PATCH v4 01/10] x86/vmx: add Intel PT MSR definitions Michał Leszczyński
2020-06-30 16:23 ` Jan Beulich
2020-06-30 17:37 ` Andrew Cooper
2020-06-30 18:03 ` Tamas K Lengyel
2020-06-30 18:27 ` Michał Leszczyński
2020-07-01 17:52 ` Andrew Cooper
2020-06-30 12:33 ` [PATCH v4 02/10] x86/vmx: add IPT cpu feature Michał Leszczyński
2020-07-01 9:49 ` Roger Pau Monné
2020-07-01 15:12 ` Julien Grall
2020-07-01 16:06 ` Andrew Cooper
2020-07-01 16:17 ` Julien Grall
2020-07-01 16:18 ` Julien Grall
2020-07-01 17:26 ` Andrew Cooper [this message]
2020-07-01 18:02 ` Julien Grall
2020-07-01 18:06 ` Andrew Cooper
2020-07-01 18:09 ` Julien Grall
2020-07-02 8:29 ` Jan Beulich
2020-07-02 8:42 ` Julien Grall
2020-07-02 8:50 ` Jan Beulich
2020-07-02 8:54 ` Julien Grall
2020-07-02 9:18 ` Jan Beulich
2020-07-02 9:57 ` Julien Grall
2020-07-02 13:30 ` Jan Beulich
2020-07-02 14:14 ` Julien Grall
2020-07-02 14:17 ` Jan Beulich
2020-07-02 14:31 ` Julien Grall
2020-07-02 20:28 ` Michał Leszczyński
2020-07-03 7:58 ` Julien Grall
2020-07-04 19:16 ` Michał Leszczyński
2020-07-01 21:42 ` Andrew Cooper
2020-07-02 8:10 ` Roger Pau Monné
2020-07-02 8:34 ` Jan Beulich
2020-07-02 20:29 ` Michał Leszczyński
2020-06-30 12:33 ` [PATCH v4 03/10] tools/libxl: add vmtrace_pt_size parameter Michał Leszczyński
2020-07-01 10:05 ` Roger Pau Monné
2020-07-02 9:00 ` Roger Pau Monné
2020-07-02 16:23 ` Michał Leszczyński
2020-07-03 9:44 ` Roger Pau Monné
2020-07-03 9:56 ` Jan Beulich
2020-07-03 10:11 ` Roger Pau Monné
2020-07-04 17:23 ` Julien Grall
2020-07-06 8:46 ` Jan Beulich
2020-07-07 8:44 ` Julien Grall
2020-07-07 9:10 ` Jan Beulich
2020-07-07 9:16 ` Julien Grall
2020-07-07 11:17 ` Michał Leszczyński
2020-07-07 11:21 ` Jan Beulich
2020-07-07 11:35 ` Michał Leszczyński
2020-07-02 10:24 ` Anthony PERARD
2020-07-04 17:48 ` Julien Grall
2020-06-30 12:33 ` [PATCH v4 04/10] x86/vmx: implement processor tracing for VMX Michał Leszczyński
2020-07-01 10:30 ` Roger Pau Monné
2020-06-30 12:33 ` [PATCH v4 05/10] common/domain: allocate vmtrace_pt_buffer Michał Leszczyński
2020-07-01 10:38 ` Roger Pau Monné
2020-07-01 15:35 ` Julien Grall
2020-06-30 12:33 ` [PATCH v4 06/10] memory: batch processing in acquire_resource() Michał Leszczyński
2020-07-01 10:46 ` Roger Pau Monné
2020-07-03 10:35 ` Julien Grall
2020-07-03 10:52 ` Paul Durrant
2020-07-03 11:17 ` Julien Grall
2020-07-03 11:22 ` Jan Beulich
2020-07-03 11:36 ` Julien Grall
2020-07-03 12:50 ` Jan Beulich
2020-07-03 11:40 ` Paul Durrant
2020-06-30 12:33 ` [PATCH v4 07/10] x86/mm: add vmtrace_buf resource type Michał Leszczyński
2020-07-01 10:52 ` Roger Pau Monné
2020-06-30 12:33 ` [PATCH v4 08/10] x86/domctl: add XEN_DOMCTL_vmtrace_op Michał Leszczyński
2020-07-01 11:00 ` Roger Pau Monné
2020-06-30 12:33 ` [PATCH v4 09/10] tools/libxc: add xc_vmtrace_* functions Michał Leszczyński
2020-07-21 10:52 ` Wei Liu
2020-06-30 12:33 ` [PATCH v4 10/10] tools/proctrace: add proctrace tool Michał Leszczyński
2020-07-02 15:10 ` Andrew Cooper
2020-07-21 10:52 ` Wei Liu
2020-06-30 12:48 ` [PATCH v4 00/10] Implement support for external IPT monitoring Hubert Jasudowicz
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