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Date: Tue, 24 Oct 2017 10:13:45 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Eduardo Valentin <eduval@amazon.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>, rkrcmar@redhat.com,
        Jonathan Corbet <corbet@lwn.net>, Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
        x86@kernel.org, Waiman Long <longman@redhat.com>, kvm@vger.kernel.org,
        linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
        "Jan H . Schoenherr" <jschoenh@amazon.de>,
        Anthony Liguori <aliguori@amazon.com>
Subject: Re: [PATCH 1/1] locking/qspinlock/x86: Avoid test-and-set when
 PV_DEDICATED is set
Message-ID: <20171024081345.GK3165@worktop.lehotels.local>
References: <1508805867-14583-1-git-send-email-eduval@amazon.com>
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On Mon, Oct 23, 2017 at 05:44:27PM -0700, Eduardo Valentin wrote:
> @@ -46,6 +48,8 @@ static inline bool virt_spin_lock(struct qspinlock *lock)
>  	if (!static_cpu_has(X86_FEATURE_HYPERVISOR))
>  		return false;
>  
> +	if (kvm_para_has_feature(KVM_FEATURE_PV_DEDICATED))
> +		return false;
>  	/*
>  	 * On hypervisors without PARAVIRT_SPINLOCKS support we fall
>  	 * back to a Test-and-Set spinlock, because fair locks have

This does not apply. Much has been changed here recently.