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
Subject: Re: [PATCH 3/3] KVM: PPC: Book3S: Add support for hwrng found on some powernv systems
Date: Wed, 02 Oct 2013 22:02:20 +0000 [thread overview]
Message-ID: <1380751340.645.68.camel@pasglop> (raw)
In-Reply-To: <20131002100224.GF17294@redhat.com>
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?).
Migration will have to be dealt with one way or another, I suppose we
will indeed need a qemu fallback.
As for why hypercall instead of MMIO, well, you'd have to ask the folks
who wrote the PAPR spec :-) It's specified as a hypercall and
implemented as such in pHyp (PowerVM). The existing guests expect it
that way.
It might have to do with the required whitening done by the hypervisor
(H_RANDOM output is supposed to be clean). It also abstracts us from the
underlying HW implementation which could in theory change.
> 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?
Why would this be a bad idea ?
Ben.
> --
> Gleb.
> --
> To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
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 08:02:20 +1000 [thread overview]
Message-ID: <1380751340.645.68.camel@pasglop> (raw)
In-Reply-To: <20131002100224.GF17294@redhat.com>
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?).
Migration will have to be dealt with one way or another, I suppose we
will indeed need a qemu fallback.
As for why hypercall instead of MMIO, well, you'd have to ask the folks
who wrote the PAPR spec :-) It's specified as a hypercall and
implemented as such in pHyp (PowerVM). The existing guests expect it
that way.
It might have to do with the required whitening done by the hypervisor
(H_RANDOM output is supposed to be clean). It also abstracts us from the
underlying HW implementation which could in theory change.
> 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?
Why would this be a bad idea ?
Ben.
> --
> Gleb.
> --
> To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
WARNING: multiple messages have this Message-ID (diff)
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
Subject: Re: [PATCH 3/3] KVM: PPC: Book3S: Add support for hwrng found on some powernv systems
Date: Thu, 03 Oct 2013 08:02:20 +1000 [thread overview]
Message-ID: <1380751340.645.68.camel@pasglop> (raw)
In-Reply-To: <20131002100224.GF17294@redhat.com>
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?).
Migration will have to be dealt with one way or another, I suppose we
will indeed need a qemu fallback.
As for why hypercall instead of MMIO, well, you'd have to ask the folks
who wrote the PAPR spec :-) It's specified as a hypercall and
implemented as such in pHyp (PowerVM). The existing guests expect it
that way.
It might have to do with the required whitening done by the hypervisor
(H_RANDOM output is supposed to be clean). It also abstracts us from the
underlying HW implementation which could in theory change.
> 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?
Why would this be a bad idea ?
Ben.
> --
> Gleb.
> --
> To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
next prev parent reply other threads:[~2013-10-02 22:02 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
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 [this message]
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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