linux-kernel - RE: [PATCH 1/1] x86/hyper-V: Allocate the IDT entry early in boot

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Date:   Sat, 9 Sep 2017 16:00:51 +0000
From:   KY Srinivasan <kys@...rosoft.com>
To:     Dan Carpenter <dan.carpenter@...cle.com>
CC:     "x86@...nel.org" <x86@...nel.org>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devel@...uxdriverproject.org" <devel@...uxdriverproject.org>,
        "olaf@...fle.de" <olaf@...fle.de>,
        "apw@...onical.com" <apw@...onical.com>,
        "jasowang@...hat.com" <jasowang@...hat.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "hpa@...or.com" <hpa@...or.com>,
        "mingo@...nel.org" <mingo@...nel.org>
Subject: RE: [PATCH 1/1] x86/hyper-V: Allocate the IDT entry early in boot



> -----Original Message-----
> From: Dan Carpenter [mailto:dan.carpenter@...cle.com]
> Sent: Saturday, September 9, 2017 4:04 AM
> To: KY Srinivasan <kys@...rosoft.com>
> Cc: x86@...nel.org; gregkh@...uxfoundation.org; linux-
> kernel@...r.kernel.org; devel@...uxdriverproject.org; olaf@...fle.de;
> apw@...onical.com; jasowang@...hat.com; tglx@...utronix.de;
> hpa@...or.com; mingo@...nel.org
> Subject: Re: [PATCH 1/1] x86/hyper-V: Allocate the IDT entry early in boot
> 
> On Fri, Sep 08, 2017 at 04:15:57PM -0700, kys@...hange.microsoft.com
> wrote:
> > From: "K. Y. Srinivasan" <kys@...rosoft.com>
> >
> > Allocate the hypervisor callback IDT entry early in the boot sequence.
> >
> 
> I'm guessing this fixes a NULL dereference or something?  The changelog
> doesn't really say why we are doing this.

The changelog does say what we are doing - allocating the IDT entry early in the boot sequence.
The current code would allocate the entry as part of registering the handler when vmbus driver
loaded and this caused a problem for the cleanup Thomas had implemented.

K. Y
> 
> regards,
> dan carpenter