From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Paolo Bonzini <pbonzini@redhat.com>
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, agraf@suse.de,
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 19:06:29 +1000 [thread overview]
Message-ID: <1380704789.645.57.camel@pasglop> (raw)
In-Reply-To: <524BDD73.3020106@redhat.com>
On Wed, 2013-10-02 at 10:46 +0200, Paolo Bonzini wrote:
>
> Thanks. Any chance you can give some numbers of a kernel hypercall and
> a userspace hypercall on Power, so we have actual data? For example a
> hypercall that returns H_PARAMETER as soon as possible.
I don't have (yet) numbers at hand but we have basically 3 places where
we can handle hypercalls:
- Kernel real mode. This is where most of our MMU stuff goes for
example unless it needs to trigger a page fault in Linux. This is
executed with translation disabled and the MMU still in guest context.
This is the fastest path since we don't take out the other threads nor
perform any expensive context change. This is where we put the
"accelerated" H_RANDOM as well.
- Kernel virtual mode. That's a full exit, so all threads are out and
MMU switched back to host Linux. Things like vhost MMIO emulation goes
there, page faults, etc...
- Qemu. This adds the round trip to userspace on top of the above.
Cheers,
Ben.
next prev parent reply other threads:[~2013-10-02 9:06 UTC|newest]
Thread overview: 46+ 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 ` [PATCH 2/3] hwrng: Add a driver for the hwrng found in power7+ systems Michael Ellerman
2013-09-26 8:01 ` Benjamin Herrenschmidt
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 9:06 ` Paolo Bonzini
2013-10-01 8:34 ` Michael Ellerman
2013-10-01 8:39 ` Gleb Natapov
2013-10-01 9:23 ` Paul Mackerras
2013-10-01 9:57 ` Gleb Natapov
2013-10-01 10:00 ` Alexander Graf
2013-10-01 9:38 ` Benjamin Herrenschmidt
2013-10-01 11:19 ` Paolo Bonzini
2013-10-01 21:44 ` Benjamin Herrenschmidt
2013-10-02 8:38 ` Paolo Bonzini
2013-10-02 5:09 ` Paul Mackerras
2013-10-02 8:46 ` Paolo Bonzini
2013-10-02 9:06 ` Benjamin Herrenschmidt [this message]
2013-10-02 9:11 ` Alexander Graf
2013-10-02 9:50 ` Alexander Graf
2013-10-02 10:02 ` Gleb Natapov
2013-10-02 13:57 ` Michael Ellerman
2013-10-02 14:08 ` Alexander Graf
2013-10-02 14:33 ` Paolo Bonzini
2013-10-02 14:36 ` Alexander Graf
2013-10-02 14:38 ` Paolo Bonzini
2013-10-02 22:45 ` Paul Mackerras
2013-10-03 5:48 ` Gleb Natapov
2013-10-03 10:06 ` Paul Mackerras
2013-10-03 12:08 ` Gleb Natapov
2013-10-02 14:37 ` Gleb Natapov
2013-10-02 22:21 ` Benjamin Herrenschmidt
2013-10-03 6:08 ` Gleb Natapov
2013-10-02 22:13 ` Benjamin Herrenschmidt
2013-10-02 14:10 ` Gleb Natapov
2013-10-02 22:15 ` Benjamin Herrenschmidt
2013-10-02 22:02 ` Benjamin Herrenschmidt
2013-10-03 5:43 ` Gleb Natapov
2013-10-03 7:22 ` Benjamin Herrenschmidt
2013-10-02 22:07 ` Benjamin Herrenschmidt
2013-10-03 6:28 ` Gleb Natapov
2013-10-02 21:58 ` Benjamin Herrenschmidt
2013-10-01 9:58 ` Paolo Bonzini
2013-09-27 14:15 ` Anshuman Khandual
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
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