From: Thomas Gleixner <tglx@linutronix.de>
To: Tony Luck <tony.luck@intel.com>
Cc: Tony Luck <tony.luck@intel.com>, 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: Fri, 17 Apr 2020 00:06:47 +0200 [thread overview]
Message-ID: <87eesnm6fc.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20200416205754.21177-3-tony.luck@intel.com>
Tony Luck <tony.luck@intel.com> writes:
> The Intel Software Developers' Manual erroneously listed bit 5 of the
> IA32_CORE_CAPABILITIES register as an architectural feature. It is
> not.
TBH. I'm really pissed off by that. We ask Intel for the past 20 years
that this non-enumerability and model checking has to stop.
Especially for the split lock festure we got assured that the Icelakes
are the only models which need the cpu match because it was too late to
add the capability bit.
> Features enumerated by IA32_CORE_CAPABILITIES are model specific and
> implementation details may vary in different cpu models. Thus it is only
> safe to trust features after checking the CPU model.
What's the point of the IA32_CORE_CAPABILITIES check if we need a model
match to figure out whether IA32_CORE_CAPABILITIES bit 5 is valid to
enumerate split lock detection?
IOW, are we going to see CPUs which end up in the match list and have
bit 5 cleared in IA32_CORE_CAPABILITIES?
Thanks,
tglx
next prev parent reply other threads:[~2020-04-16 22:06 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 [this message]
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
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
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