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Date: Thu, 9 Nov 2017 11:51:08 +0100 (CET)
From: Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 02/30] x86, tlb: make CR4-based TLB flushes more robust
In-Reply-To: <20171109104813.h67cts3mmr5zh4kd@pd.tnic>
Message-ID: <alpine.DEB.2.20.1711091149500.1839@nanos>
References: <20171108194646.907A1942@viggo.jf.intel.com> <20171108194649.61C7A485@viggo.jf.intel.com> <20171109104813.h67cts3mmr5zh4kd@pd.tnic>
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Sender: owner-linux-mm@kvack.org
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To: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>, luto@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, moritz.lipp@iaik.tugraz.at, daniel.gruss@iaik.tugraz.at, michael.schwarz@iaik.tugraz.at, richard.fellner@student.tugraz.at, torvalds@linux-foundation.org, keescook@google.com, hughd@google.com, x86@kernel.org

On Thu, 9 Nov 2017, Borislav Petkov wrote:
> On Wed, Nov 08, 2017 at 11:46:49AM -0800, Dave Hansen wrote:
> > +	/* Put original CR4 value back: */
> >  	native_write_cr4(cr4);
> >  }
> 
> Btw, Andy, we read the CR4 shadow in that function but we don't update
> it. Why?

Because its the same as before.

> > +   /* Put original CR4 value back: */
> >     native_write_cr4(cr4);

Thanks,

	tglx

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