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

[Ingo Molnar]

* KY Srinivasan <kys@xxxxxxxxxxxxx> wrote:

> 
> 
> > -----Original Message-----
> > From: Dan Carpenter [mailto:dan.carpenter@xxxxxxxxxx]
> > Sent: Saturday, September 9, 2017 4:04 AM
> > To: KY Srinivasan <kys@xxxxxxxxxxxxx>
> > Cc: x86@xxxxxxxxxx; gregkh@xxxxxxxxxxxxxxxxxxx; linux-
> > kernel@xxxxxxxxxxxxxxx; devel@xxxxxxxxxxxxxxxxxxxxxx; olaf@xxxxxxxxx;
> > apw@xxxxxxxxxxxxx; jasowang@xxxxxxxxxx; tglx@xxxxxxxxxxxxx;
> > hpa@xxxxxxxxx; mingo@xxxxxxxxxx
> > 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@xxxxxxxxxxxxxxxxxxxxxx
> > wrote:
> > > From: "K. Y. Srinivasan" <kys@xxxxxxxxxxxxx>
> > >
> > > 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.

But the question was the 'why', not the 'what' - so Dan's question is
fully justified ...

> 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.

I've put this explanation into the changelog.

Thanks,

	Ingo