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From: Paolo Bonzini <pbonzini@redhat.com>
To: Alexander Graf <agraf@suse.de>
Cc: Michael Ellerman <michael@ellerman.id.au>,
	Gleb Natapov <gleb@redhat.com>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	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 14:33:18 +0000	[thread overview]
Message-ID: <524C2EAE.7090209@redhat.com> (raw)
In-Reply-To: <029A8D6C-C23C-42B2-8C26-D76B59E2C9DD@suse.de>

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?

Paolo

WARNING: multiple messages have this Message-ID (diff)
From: Paolo Bonzini <pbonzini@redhat.com>
To: Alexander Graf <agraf@suse.de>
Cc: tytso@mit.edu, kvm@vger.kernel.org,
	Gleb Natapov <gleb@redhat.com>,
	linuxppc-dev@ozlabs.org, linux-kernel@vger.kernel.org,
	kvm-ppc@vger.kernel.org, herbert@gondor.hengli.com.au,
	Paul Mackerras <paulus@samba.org>,
	mpm@selenic.com
Subject: Re: [PATCH 3/3] KVM: PPC: Book3S: Add support for hwrng found on some powernv systems
Date: Wed, 02 Oct 2013 16:33:18 +0200	[thread overview]
Message-ID: <524C2EAE.7090209@redhat.com> (raw)
In-Reply-To: <029A8D6C-C23C-42B2-8C26-D76B59E2C9DD@suse.de>

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?

Paolo

WARNING: multiple messages have this Message-ID (diff)
From: Paolo Bonzini <pbonzini@redhat.com>
To: Alexander Graf <agraf@suse.de>
Cc: Michael Ellerman <michael@ellerman.id.au>,
	Gleb Natapov <gleb@redhat.com>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	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 16:33:18 +0200	[thread overview]
Message-ID: <524C2EAE.7090209@redhat.com> (raw)
In-Reply-To: <029A8D6C-C23C-42B2-8C26-D76B59E2C9DD@suse.de>

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?

Paolo

  reply	other threads:[~2013-10-02 14:33 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 [this message]
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
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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