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From: David Laight <David.Laight@ACULAB.COM>
To: 'Xiaoyao Li' <xiaoyao.li@intel.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	Ingo Molnar <mingo@redhat.com>, "Borislav Petkov" <bp@alien8.de>,
	Andy Lutomirski <luto@amacapital.net>
Cc: "x86@kernel.org" <x86@kernel.org>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH v2 3/6] kvm: x86: Emulate split-lock access as a write
Date: Tue, 11 Feb 2020 14:34:11 +0000	[thread overview]
Message-ID: <973e772012ce4f0f9a689fe33608236a@AcuMS.aculab.com> (raw)
In-Reply-To: <f6d37da1-ce56-7a11-63d8-32126b76094a@intel.com>

From: Xiaoyao Li
> Sent: 11 February 2020 14:03
...
> Alright, I don't know the history of TEST_CTRL, there is a bit 31 in it
> which means "Disable LOCK# assertion for split locked access" when set.
> Bit 31 exists for a long period, but linux seems not use it so I guess
> it may be a testing purpose bit.

My brain remembers something about some system just ignoring
locked accesses for misaligned transfers.
Trouble is it was probably nearly 30 years ago and there are
no details coming out of 'long term storage'.

It might be that some systems I had either set this bit
or acted as if it was set.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)


  reply	other threads:[~2020-02-11 14:34 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-03 15:16 [PATCH v2 0/6] kvm/split_lock: Add feature split lock detection support in kvm Xiaoyao Li
2020-02-03 15:16 ` [PATCH v2 1/6] x86/split_lock: Add and export get_split_lock_detect_state() Xiaoyao Li
2020-02-03 21:45   ` Sean Christopherson
2020-02-03 15:16 ` [PATCH v2 2/6] x86/split_lock: Add and export split_lock_detect_set() Xiaoyao Li
2020-02-03 15:16 ` [PATCH v2 3/6] kvm: x86: Emulate split-lock access as a write Xiaoyao Li
2020-02-03 20:54   ` Sean Christopherson
2020-02-04  2:55     ` Xiaoyao Li
2020-02-11 12:20   ` Paolo Bonzini
2020-02-11 13:22     ` Thomas Gleixner
2020-02-11 13:34       ` Paolo Bonzini
2020-02-11 14:02         ` Xiaoyao Li
2020-02-11 14:34           ` David Laight [this message]
2020-02-27  0:11         ` Sean Christopherson
2020-03-12 11:42           ` Xiaoyao Li
2020-03-12 15:00             ` Paolo Bonzini
2020-02-03 15:16 ` [PATCH v2 4/6] kvm: vmx: Extend VMX's #AC handding for split lock in guest Xiaoyao Li
2020-02-03 21:14   ` Sean Christopherson
2020-02-04  6:46     ` Xiaoyao Li
2020-02-10 21:30       ` Sean Christopherson
2020-02-03 15:16 ` [PATCH v2 5/6] kvm: x86: Emulate MSR IA32_CORE_CAPABILITIES Xiaoyao Li
2020-02-03 21:43   ` Sean Christopherson
2020-02-04  9:19     ` Xiaoyao Li
2020-02-04  9:37       ` Peter Zijlstra
2020-02-11  3:52         ` Andy Lutomirski
2020-02-11 12:38           ` Peter Zijlstra
2020-02-03 15:16 ` [PATCH v2 6/6] x86: vmx: virtualize split lock detection Xiaoyao Li
2020-02-03 15:58   ` Xiaoyao Li
2020-02-03 18:52   ` Andy Lutomirski
2020-02-03 21:42   ` Sean Christopherson
2020-02-04  2:52     ` Xiaoyao Li
2020-02-04  5:35       ` Sean Christopherson

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