Message-ID: <1380751642.645.71.camel@pasglop>
Subject: Re: [PATCH 3/3] KVM: PPC: Book3S: Add support for hwrng found on
 some powernv systems
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Gleb Natapov <gleb@redhat.com>
Cc: Alexander Graf <agraf@suse.de>, Paolo Bonzini <pbonzini@redhat.com>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <michael@ellerman.id.au>,
        linux-kernel@vger.kernel.org, mpm@selenic.com,
        herbert@gondor.hengli.com.au, linuxppc-dev@ozlabs.org,
        kvm@vger.kernel.org, kvm-ppc@vger.kernel.org, tytso@mit.edu
Date: Thu, 03 Oct 2013 08:07:22 +1000
In-Reply-To: <20131002100224.GF17294@redhat.com>
References: <5243F933.7000907@redhat.com> <20131001083426.GB27484@concordia>
	 <20131001083908.GA17294@redhat.com> <1380620338.645.22.camel@pasglop>
	 <524AAFAA.3010801@redhat.com> <20131002050940.GA25363@drongo>
	 <524BDD73.3020106@redhat.com> <1380704789.645.57.camel@pasglop>
	 <668E4650-BC22-4CBF-A282-E7875DF29DB6@suse.de>
	 <3CBF5732-E7EE-4C96-8132-6D7B77270DAF@suse.de>
	 <20131002100224.GF17294@redhat.com>
Content-Type: text/plain; charset="UTF-8"
Mime-Version: 1.0
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1660
Lines: 40

On Wed, 2013-10-02 at 13:02 +0300, Gleb Natapov wrote:

> Yes, I alluded to it in my email to Paul and Paolo asked also. How this
> interface is disabled? Also hwrnd is MMIO in a host why guest needs to
> use hypercall instead of emulating the device (in kernel or somewhere
> else?). Another things is that on a host hwrnd is protected from
> direct userspace access by virtue of been a device, but guest code (event
> kernel mode) is userspace as far as hosts security model goes, so by
> implementing this hypercall in a way that directly access hwrnd you
> expose hwrnd to a userspace unconditionally. Why is this a good idea? 

BTW. Is this always going to be like this ?

Every *single* architectural or design decision we make for our
architecture has to be justified 30 times over, every piece of code bike
shedded to oblivion for month, etc... ?

Do we always have to finally get to some kind of agreement on design, go
to the 6 month bike-shedding phase, just to have somebody else come up
and start re-questioning the whole original design (without any
understanding of our specific constraints of course) ?

You guys are the most horrendous community I have ever got to work with.
It's simply impossible to get anything done in any reasonable time
frame .

At this stage, it would have taken us an order of magnitude less time to
simply rewrite an entire hypervisor from scratch.

This is sad.

Ben.


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/