public inbox for linux-kernel@vger.kernel.org
 help / color / mirror / Atom feed
From: Thomas Gleixner <tglx@linutronix.de>
To: Xiaoyao Li <xiaoyao.li@intel.com>, "Luck\,
	Tony" <tony.luck@intel.com>, Paolo Bonzini <pbonzini@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>, Fenghua Yu <fenghua.yu@intel.com>,
	Borislav Petkov <bp@alien8.de>, H Peter Anvin <hpa@zytor.com>,
	Ashok Raj <ashok.raj@intel.com>,
	Ravi V Shankar <ravi.v.shankar@intel.com>,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	Andy Lutomirski <luto@kernel.org>,
	linux-kernel@vger.kernel.org, x86@kernel.org
Subject: Re: [PATCH 2/3] x86/split_lock: Bits in IA32_CORE_CAPABILITIES are not architectural
Date: Sat, 18 Apr 2020 11:27:24 +0200	[thread overview]
Message-ID: <87wo6dxhxf.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <651504d9-f458-1d25-870d-b8c55061be45@intel.com>

Xiaoyao,

can you please trim your replies?

Xiaoyao Li <xiaoyao.li@intel.com> writes:
> On 4/18/2020 5:07 AM, Thomas Gleixner wrote:
>> + * Bits in the IA32_CORE_CAPABILITIES are not architectural, so they should
>> + * only be trusted if it is confirmed that a CPU model implements a
>> + * specific feature at a particular bit position.
>> + *
>> + * The possible driver data field values:
>> + *
>> + * - 0: CPU models that are known to have the per-core split-lock detection
>> + *	feature even though they do not enumerate IA32_CORE_CAPABILITIES.
>> + *
>> + * - 1: CPU models which may enumerate IA32_CORE_CAPABILITIES and if so use
>> + *      bit 5 to enumerate the per-core split-lock detection feature.
>
> So now, it's tightly associated with CPU model, which makes it harder to 
> expose this feature to guest. For guest, the CPU model can be configured 
> to anything.
>
> As suggested by Sean internally, we'd better use a KVM CPUID to expose 
> it to guest, which makes it independent of CPU model.

Works for me.

Thanks,

        tglx

  parent reply	other threads:[~2020-04-18  9:27 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-16 20:57 [PATCH 0/3] Split lock enumeration cleanup and fixes Tony Luck
2020-04-16 20:57 ` [PATCH 1/3] x86/split_lock: Update to use X86_MATCH_INTEL_FAM6_MODEL() Tony Luck
2020-04-17 10:20   ` [tip: x86/urgent] " tip-bot2 for Tony Luck
2020-04-16 20:57 ` [PATCH 2/3] x86/split_lock: Bits in IA32_CORE_CAPABILITIES are not architectural Tony Luck
2020-04-16 22:06   ` Thomas Gleixner
2020-04-16 22:33     ` Luck, Tony
2020-04-17  9:48       ` Thomas Gleixner
2020-04-17 10:04   ` Thomas Gleixner
2020-04-17 17:06     ` Luck, Tony
2020-04-17 19:29       ` Thomas Gleixner
2020-04-17 19:56         ` Luck, Tony
2020-04-17 20:48           ` Thomas Gleixner
2020-04-17 21:07             ` Thomas Gleixner
2020-04-17 21:19               ` Luck, Tony
2020-04-17 22:18                 ` Thomas Gleixner
2020-04-18  4:15               ` Xiaoyao Li
2020-04-18  4:35                 ` Sean Christopherson
2020-04-18  9:27                 ` Thomas Gleixner [this message]
2020-04-18 10:54   ` [tip: x86/urgent] " tip-bot2 for Tony Luck
2020-04-16 20:57 ` [PATCH 3/3] x86/split_lock: Add Tremont family CPU models Tony Luck
2020-04-18 10:54   ` [tip: x86/urgent] " tip-bot2 for Tony Luck
2020-04-16 21:35 ` [PATCH 0/3] Split lock enumeration cleanup and fixes Thomas Gleixner
2020-04-16 21:39   ` Luck, Tony

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=87wo6dxhxf.fsf@nanos.tec.linutronix.de \
    --to=tglx@linutronix.de \
    --cc=ashok.raj@intel.com \
    --cc=bp@alien8.de \
    --cc=fenghua.yu@intel.com \
    --cc=hpa@zytor.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=luto@kernel.org \
    --cc=mingo@kernel.org \
    --cc=pbonzini@redhat.com \
    --cc=ravi.v.shankar@intel.com \
    --cc=sean.j.christopherson@intel.com \
    --cc=tony.luck@intel.com \
    --cc=x86@kernel.org \
    --cc=xiaoyao.li@intel.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox