From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Gleb Natapov <gleb@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Alexander Graf <agraf@suse.de>,
Michael Ellerman <michael@ellerman.id.au>,
Paul Mackerras <paulus@samba.org>,
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
Subject: Re: [PATCH 3/3] KVM: PPC: Book3S: Add support for hwrng found on some powernv systems
Date: Wed, 02 Oct 2013 22:21:20 +0000 [thread overview]
Message-ID: <1380752480.645.74.camel@pasglop> (raw)
In-Reply-To: <20131002143720.GK17294@redhat.com>
On Wed, 2013-10-02 at 17:37 +0300, Gleb Natapov wrote:
> On Wed, Oct 02, 2013 at 04:33:18PM +0200, Paolo Bonzini wrote:
> > Il 02/10/2013 16:08, Alexander Graf ha scritto:
> > > > The hwrng is accessible by host userspace via /dev/mem.
> > >
> > > A guest should live on the same permission level as a user space
> > > application. If you run QEMU as UID 1000 without access to /dev/mem, why
> > > should the guest suddenly be able to directly access a memory location
> > > (MMIO) it couldn't access directly through a normal user space interface.
> > >
> > > It's basically a layering violation.
> >
> > With Michael's earlier patch in this series, the hwrng is accessible by
> > host userspace via /dev/hwrng, no?
> >
> Access to which can be controlled by its permission. Permission of
> /dev/kvm may be different. If we route hypercall via userspace and
> configure qemu to get entropy from /dev/hwrng everything will fall
> nicely together (except performance).
Yes, except abysmall performance and a lot more code for something
completely and utterly pointless .... nice.
Ben.
WARNING: multiple messages have this Message-ID (diff)
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Gleb Natapov <gleb@redhat.com>
Cc: tytso@mit.edu, kvm@vger.kernel.org, linuxppc-dev@ozlabs.org,
Alexander Graf <agraf@suse.de>,
kvm-ppc@vger.kernel.org, linux-kernel@vger.kernel.org,
herbert@gondor.hengli.com.au, Paul Mackerras <paulus@samba.org>,
mpm@selenic.com, Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH 3/3] KVM: PPC: Book3S: Add support for hwrng found on some powernv systems
Date: Thu, 03 Oct 2013 08:21:20 +1000 [thread overview]
Message-ID: <1380752480.645.74.camel@pasglop> (raw)
In-Reply-To: <20131002143720.GK17294@redhat.com>
On Wed, 2013-10-02 at 17:37 +0300, Gleb Natapov wrote:
> On Wed, Oct 02, 2013 at 04:33:18PM +0200, Paolo Bonzini wrote:
> > Il 02/10/2013 16:08, Alexander Graf ha scritto:
> > > > The hwrng is accessible by host userspace via /dev/mem.
> > >
> > > A guest should live on the same permission level as a user space
> > > application. If you run QEMU as UID 1000 without access to /dev/mem, why
> > > should the guest suddenly be able to directly access a memory location
> > > (MMIO) it couldn't access directly through a normal user space interface.
> > >
> > > It's basically a layering violation.
> >
> > With Michael's earlier patch in this series, the hwrng is accessible by
> > host userspace via /dev/hwrng, no?
> >
> Access to which can be controlled by its permission. Permission of
> /dev/kvm may be different. If we route hypercall via userspace and
> configure qemu to get entropy from /dev/hwrng everything will fall
> nicely together (except performance).
Yes, except abysmall performance and a lot more code for something
completely and utterly pointless .... nice.
Ben.
WARNING: multiple messages have this Message-ID (diff)
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Gleb Natapov <gleb@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Alexander Graf <agraf@suse.de>,
Michael Ellerman <michael@ellerman.id.au>,
Paul Mackerras <paulus@samba.org>,
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
Subject: Re: [PATCH 3/3] KVM: PPC: Book3S: Add support for hwrng found on some powernv systems
Date: Thu, 03 Oct 2013 08:21:20 +1000 [thread overview]
Message-ID: <1380752480.645.74.camel@pasglop> (raw)
In-Reply-To: <20131002143720.GK17294@redhat.com>
On Wed, 2013-10-02 at 17:37 +0300, Gleb Natapov wrote:
> On Wed, Oct 02, 2013 at 04:33:18PM +0200, Paolo Bonzini wrote:
> > Il 02/10/2013 16:08, Alexander Graf ha scritto:
> > > > The hwrng is accessible by host userspace via /dev/mem.
> > >
> > > A guest should live on the same permission level as a user space
> > > application. If you run QEMU as UID 1000 without access to /dev/mem, why
> > > should the guest suddenly be able to directly access a memory location
> > > (MMIO) it couldn't access directly through a normal user space interface.
> > >
> > > It's basically a layering violation.
> >
> > With Michael's earlier patch in this series, the hwrng is accessible by
> > host userspace via /dev/hwrng, no?
> >
> Access to which can be controlled by its permission. Permission of
> /dev/kvm may be different. If we route hypercall via userspace and
> configure qemu to get entropy from /dev/hwrng everything will fall
> nicely together (except performance).
Yes, except abysmall performance and a lot more code for something
completely and utterly pointless .... nice.
Ben.
next prev parent reply other threads:[~2013-10-02 22:21 UTC|newest]
Thread overview: 146+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-26 6:31 [PATCH 1/3] powerpc: Implement arch_get_random_long/int() for powernv Michael Ellerman
2013-09-26 6:31 ` Michael Ellerman
2013-09-26 6:31 ` Michael Ellerman
2013-09-26 6:31 ` Michael Ellerman
2013-09-26 6:31 ` [PATCH 2/3] hwrng: Add a driver for the hwrng found in power7+ systems Michael Ellerman
2013-09-26 6:31 ` Michael Ellerman
2013-09-26 6:31 ` Michael Ellerman
2013-09-26 6:31 ` Michael Ellerman
2013-09-26 8:01 ` Benjamin Herrenschmidt
2013-09-26 8:01 ` Benjamin Herrenschmidt
2013-09-26 8:01 ` Benjamin Herrenschmidt
2013-10-01 8:25 ` Michael Ellerman
2013-10-01 8:25 ` Michael Ellerman
2013-10-01 8:25 ` Michael Ellerman
2013-09-26 6:31 ` [PATCH 3/3] KVM: PPC: Book3S: Add support for hwrng found on some powernv systems Michael Ellerman
2013-09-26 6:31 ` Michael Ellerman
2013-09-26 6:31 ` Michael Ellerman
2013-09-26 6:31 ` Michael Ellerman
2013-09-26 9:06 ` Paolo Bonzini
2013-09-26 9:06 ` Paolo Bonzini
2013-09-26 9:06 ` Paolo Bonzini
2013-09-26 9:06 ` Paolo Bonzini
2013-10-01 8:34 ` Michael Ellerman
2013-10-01 8:34 ` Michael Ellerman
2013-10-01 8:34 ` Michael Ellerman
2013-10-01 8:34 ` Michael Ellerman
2013-10-01 8:39 ` Gleb Natapov
2013-10-01 8:39 ` Gleb Natapov
2013-10-01 8:39 ` Gleb Natapov
2013-10-01 9:23 ` Paul Mackerras
2013-10-01 9:23 ` Paul Mackerras
2013-10-01 9:23 ` Paul Mackerras
2013-10-01 9:57 ` Gleb Natapov
2013-10-01 9:57 ` Gleb Natapov
2013-10-01 9:57 ` Gleb Natapov
2013-10-01 10:00 ` Alexander Graf
2013-10-01 10:00 ` Alexander Graf
2013-10-01 10:00 ` Alexander Graf
2013-10-01 9:38 ` Benjamin Herrenschmidt
2013-10-01 9:38 ` Benjamin Herrenschmidt
2013-10-01 9:38 ` Benjamin Herrenschmidt
2013-10-01 11:19 ` Paolo Bonzini
2013-10-01 11:19 ` Paolo Bonzini
2013-10-01 11:19 ` Paolo Bonzini
2013-10-01 21:44 ` Benjamin Herrenschmidt
2013-10-01 21:44 ` Benjamin Herrenschmidt
2013-10-01 21:44 ` Benjamin Herrenschmidt
2013-10-02 8:38 ` Paolo Bonzini
2013-10-02 8:38 ` Paolo Bonzini
2013-10-02 8:38 ` Paolo Bonzini
2013-10-02 5:09 ` Paul Mackerras
2013-10-02 5:09 ` Paul Mackerras
2013-10-02 5:09 ` Paul Mackerras
2013-10-02 8:46 ` Paolo Bonzini
2013-10-02 8:46 ` Paolo Bonzini
2013-10-02 8:46 ` Paolo Bonzini
2013-10-02 9:06 ` Benjamin Herrenschmidt
2013-10-02 9:06 ` Benjamin Herrenschmidt
2013-10-02 9:06 ` Benjamin Herrenschmidt
2013-10-02 9:11 ` Alexander Graf
2013-10-02 9:11 ` Alexander Graf
2013-10-02 9:11 ` Alexander Graf
2013-10-02 9:50 ` Alexander Graf
2013-10-02 9:50 ` Alexander Graf
2013-10-02 9:50 ` Alexander Graf
2013-10-02 10:02 ` Gleb Natapov
2013-10-02 10:02 ` Gleb Natapov
2013-10-02 10:02 ` Gleb Natapov
2013-10-02 13:57 ` Michael Ellerman
2013-10-02 13:57 ` Michael Ellerman
2013-10-02 13:57 ` Michael Ellerman
2013-10-02 14:08 ` Alexander Graf
2013-10-02 14:08 ` Alexander Graf
2013-10-02 14:08 ` Alexander Graf
2013-10-02 14:33 ` Paolo Bonzini
2013-10-02 14:33 ` Paolo Bonzini
2013-10-02 14:33 ` Paolo Bonzini
2013-10-02 14:36 ` Alexander Graf
2013-10-02 14:36 ` Alexander Graf
2013-10-02 14:36 ` Alexander Graf
2013-10-02 14:38 ` Paolo Bonzini
2013-10-02 14:38 ` Paolo Bonzini
2013-10-02 14:38 ` Paolo Bonzini
2013-10-02 22:45 ` Paul Mackerras
2013-10-02 22:45 ` Paul Mackerras
2013-10-02 22:45 ` Paul Mackerras
2013-10-03 5:48 ` Gleb Natapov
2013-10-03 5:48 ` Gleb Natapov
2013-10-03 5:48 ` Gleb Natapov
2013-10-03 10:06 ` Paul Mackerras
2013-10-03 10:06 ` Paul Mackerras
2013-10-03 10:06 ` Paul Mackerras
2013-10-03 12:08 ` Gleb Natapov
2013-10-03 12:08 ` Gleb Natapov
2013-10-03 12:08 ` Gleb Natapov
2013-10-02 14:37 ` Gleb Natapov
2013-10-02 14:37 ` Gleb Natapov
2013-10-02 14:37 ` Gleb Natapov
2013-10-02 22:21 ` Benjamin Herrenschmidt [this message]
2013-10-02 22:21 ` Benjamin Herrenschmidt
2013-10-02 22:21 ` Benjamin Herrenschmidt
2013-10-03 6:08 ` Gleb Natapov
2013-10-03 6:08 ` Gleb Natapov
2013-10-03 6:08 ` Gleb Natapov
2013-10-02 22:13 ` Benjamin Herrenschmidt
2013-10-02 22:13 ` Benjamin Herrenschmidt
2013-10-02 22:13 ` Benjamin Herrenschmidt
2013-10-02 14:10 ` Gleb Natapov
2013-10-02 14:10 ` Gleb Natapov
2013-10-02 14:10 ` Gleb Natapov
2013-10-02 22:15 ` Benjamin Herrenschmidt
2013-10-02 22:15 ` Benjamin Herrenschmidt
2013-10-02 22:15 ` Benjamin Herrenschmidt
2013-10-02 22:02 ` Benjamin Herrenschmidt
2013-10-02 22:02 ` Benjamin Herrenschmidt
2013-10-02 22:02 ` Benjamin Herrenschmidt
2013-10-03 5:43 ` Gleb Natapov
2013-10-03 5:43 ` Gleb Natapov
2013-10-03 5:43 ` Gleb Natapov
2013-10-03 7:22 ` Benjamin Herrenschmidt
2013-10-03 7:22 ` Benjamin Herrenschmidt
2013-10-03 7:22 ` Benjamin Herrenschmidt
2013-10-02 22:07 ` Benjamin Herrenschmidt
2013-10-02 22:07 ` Benjamin Herrenschmidt
2013-10-02 22:07 ` Benjamin Herrenschmidt
2013-10-03 6:28 ` Gleb Natapov
2013-10-03 6:28 ` Gleb Natapov
2013-10-03 6:28 ` Gleb Natapov
2013-10-02 21:58 ` Benjamin Herrenschmidt
2013-10-02 21:58 ` Benjamin Herrenschmidt
2013-10-02 21:58 ` Benjamin Herrenschmidt
2013-10-01 9:58 ` Paolo Bonzini
2013-10-01 9:58 ` Paolo Bonzini
2013-10-01 9:58 ` Paolo Bonzini
2013-10-01 9:58 ` Paolo Bonzini
2013-09-27 14:15 ` Anshuman Khandual
2013-09-27 14:27 ` Anshuman Khandual
2013-09-27 14:15 ` Anshuman Khandual
2013-09-27 14:15 ` Anshuman Khandual
2013-10-01 8:36 ` Michael Ellerman
2013-10-01 8:36 ` Michael Ellerman
2013-10-01 8:36 ` Michael Ellerman
2013-10-01 8:36 ` Michael Ellerman
2013-09-26 7:58 ` [PATCH 1/3] powerpc: Implement arch_get_random_long/int() for powernv Benjamin Herrenschmidt
2013-09-26 7:58 ` Benjamin Herrenschmidt
2013-09-26 7:58 ` Benjamin Herrenschmidt
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