Re: [PATCH v4 0/3] qspinlock: Introducing a 4-byte queue spinlock

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To: Raghavendra K T <raghavendra.kt@xxxxxxxxxxxxxxxxxx>
Subject: Re: [PATCH v4 0/3] qspinlock: Introducing a 4-byte queue spinlock
From: Waiman Long <waiman.long@xxxxxx>
Date: Fri, 21 Feb 2014 12:02:26 -0500
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>, Peter Zijlstra <peterz@xxxxxxxxxxxxx>, "H. Peter Anvin" <hpa@xxxxxxxxx>, Thomas Gleixner <tglx@xxxxxxxxxxxxx>, Ingo Molnar <mingo@xxxxxxxxxx>, Arnd Bergmann <arnd@xxxxxxxx>, "linux-arch@xxxxxxxxxxxxxxx" <linux-arch@xxxxxxxxxxxxxxx>, the arch/x86 maintainers <x86@xxxxxxxxxx>, Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>, Steven Rostedt <rostedt@xxxxxxxxxxx>, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>, Michel Lespinasse <walken@xxxxxxxxxx>, Andi Kleen <andi@xxxxxxxxxxxxxx>, Rik van Riel <riel@xxxxxxxxxx>, "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>, George Spelvin <linux@xxxxxxxxxxx>, Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx>, Daniel J Blueman <daniel@xxxxxxxxxxxxx>, Alexander Fyodorov <halcy@xxxxxxxxx>, Aswin Chandramouleeswaran <aswin@xxxxxx>, Scott J Norton <scott.norton@xxxxxx>, Thavatchai Makphaibulchoke <thavatchai.makpahibulchoke@xxxxxx>
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On 02/20/2014 02:32 PM, Raghavendra K T wrote:

On 02/20/2014 11:24 PM, Waiman Long wrote:

Now the key is how to detect if a kernel is really running in a PV
environment. I need to ask some virtualization experts on that.


For kvm you could just follow,
kvm_spinlock_init_jump() and KVM_FEATURE_* encoding in cpuid
part __do_cpuid_ent().

I saw that in the arch/x86/kernel/kvm.c file. So I think I can use thereturned value of kvm_para_available() to decide if it is running in aKVM guest. However, I am not so sure of what to use in xen.


-Longman
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References:
- [PATCH v4 0/3] qspinlock: Introducing a 4-byte queue spinlock
  - From: Waiman Long
- Re: [PATCH v4 0/3] qspinlock: Introducing a 4-byte queue spinlock
  - From: H. Peter Anvin
- Re: [PATCH v4 0/3] qspinlock: Introducing a 4-byte queue spinlock
  - From: Peter Zijlstra
- Re: [PATCH v4 0/3] qspinlock: Introducing a 4-byte queue spinlock
  - From: Waiman Long
- Re: [PATCH v4 0/3] qspinlock: Introducing a 4-byte queue spinlock
  - From: Peter Zijlstra
- Re: [PATCH v4 0/3] qspinlock: Introducing a 4-byte queue spinlock
  - From: Waiman Long
- Re: [PATCH v4 0/3] qspinlock: Introducing a 4-byte queue spinlock
  - From: Peter Zijlstra
- Re: [PATCH v4 0/3] qspinlock: Introducing a 4-byte queue spinlock
  - From: Waiman Long
- Re: [PATCH v4 0/3] qspinlock: Introducing a 4-byte queue spinlock
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  - From: Waiman Long
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