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From:   Thomas Gleixner <tglx@linutronix.de>
To:     Boris Ostrovsky <boris.ostrovsky@oracle.com>,
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Cc:     x86@kernel.org, "Paul E. McKenney" <paulmck@kernel.org>,
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        "Peter Zijlstra \(Intel\)" <peterz@infradead.org>
Subject: Re: [patch V5 24/38] x86/entry: Provide IDTENTRY_SYSVEC
In-Reply-To: <78bf7499-b810-4e71-46c0-3d86f6c6d3d7@oracle.com>
References: <20200512210059.056244513@linutronix.de> <20200512213811.844041484@linutronix.de> <78bf7499-b810-4e71-46c0-3d86f6c6d3d7@oracle.com>
Date:   Fri, 15 May 2020 10:52:15 +0200
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Boris Ostrovsky <boris.ostrovsky@oracle.com> writes:

> On 5/12/20 5:01 PM, Thomas Gleixner wrote:
>> +
>> +/**
>> + * DEFINE_IDTENTRY_SYSVEC - Emit code for system vector IDT entry points
>> + * @func:	Function name of the entry point
>> + *
>> + * idtentry_enter/exit() and irq_enter/exit_rcu() are invoked before the
>> + * function body. KVM L1D flush request is set.
>
>
> This is used for entry points for Xen and hyperV as well. Even though
> it's harmless at the moment, do we still want to set this flag for non-KVM?

Right, it's pointless for !KVM, but we have set this unconditionally
since the l1tf mess was introduced. I'm not sure whether it's worth to
optimize the single store out.

Thanks,

        tglx