On Thu, Oct 03, 2013 at 08:21:20AM +1000, Benjamin Herrenschmidt wrote:
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
On Thu, Oct 03, 2013 at 08:07:22AM +1000, Benjamin Herrenschmidt wrote:
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
On Thu, 2013-10-03 at 08:43 +0300, Gleb Natapov wrote:
Why it can be a bad idea? User can drain hwrng continuously making other
users of it much slower, or even worse, making them fall back to another
much less reliable, source of entropy.
Not in a very significant way, we generate entropy at
On Thu, Oct 03, 2013 at 08:48:03AM +0300, Gleb Natapov wrote:
On Thu, Oct 03, 2013 at 08:45:42AM +1000, Paul Mackerras wrote:
On Wed, Oct 02, 2013 at 04:36:05PM +0200, Alexander Graf wrote:
On 02.10.2013, at 16:33, Paolo Bonzini wrote:
Il 02/10/2013 16:08, Alexander Graf ha
On Thu, Oct 03, 2013 at 08:06:30PM +1000, Paul Mackerras wrote:
On Thu, Oct 03, 2013 at 08:48:03AM +0300, Gleb Natapov wrote:
On Thu, Oct 03, 2013 at 08:45:42AM +1000, Paul Mackerras wrote:
On Wed, Oct 02, 2013 at 04:36:05PM +0200, Alexander Graf wrote:
On 02.10.2013, at 16:33,
Il 01/10/2013 23:44, Benjamin Herrenschmidt ha scritto:
On Tue, 2013-10-01 at 13:19 +0200, Paolo Bonzini wrote:
Il 01/10/2013 11:38, Benjamin Herrenschmidt ha scritto:
So for the sake of that dogma you are going to make us do something that
is about 100 times slower ? (and possibly involves
Il 02/10/2013 07:09, Paul Mackerras ha scritto:
On Tue, Oct 01, 2013 at 01:19:06PM +0200, Paolo Bonzini wrote:
Anyhow, I would like to know more about this hwrng and hypercall.
Does the hwrng return random numbers (like rdrand) or real entropy (like
rdseed that Intel will add in Broadwell)?
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
On 02.10.2013, at 11:06, Benjamin Herrenschmidt wrote:
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
On 02.10.2013, at 11:11, Alexander Graf wrote:
On 02.10.2013, at 11:06, Benjamin Herrenschmidt wrote:
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
On Wed, Oct 02, 2013 at 11:50:50AM +0200, Alexander Graf wrote:
On 02.10.2013, at 11:11, Alexander Graf wrote:
On 02.10.2013, at 11:06, Benjamin Herrenschmidt wrote:
On Wed, 2013-10-02 at 10:46 +0200, Paolo Bonzini wrote:
Thanks. Any chance you can give some numbers of a
On Wed, 2013-10-02 at 13:02 +0300, Gleb Natapov wrote:
On Wed, Oct 02, 2013 at 11:50:50AM +0200, Alexander Graf wrote:
On 02.10.2013, at 11:11, Alexander Graf wrote:
So how do you solve live migration between a kernel that has this patch and
one that doesn't?
Yes, I alluded to it
On 02.10.2013, at 15:57, Michael Ellerman wrote:
On Wed, 2013-10-02 at 13:02 +0300, Gleb Natapov wrote:
On Wed, Oct 02, 2013 at 11:50:50AM +0200, Alexander Graf wrote:
On 02.10.2013, at 11:11, Alexander Graf wrote:
So how do you solve live migration between a kernel that has this patch
On Wed, Oct 02, 2013 at 11:57:55PM +1000, Michael Ellerman wrote:
On Wed, 2013-10-02 at 13:02 +0300, Gleb Natapov wrote:
On Wed, Oct 02, 2013 at 11:50:50AM +0200, Alexander Graf wrote:
On 02.10.2013, at 11:11, Alexander Graf wrote:
So how do you solve live migration between a
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
Il 02/10/2013 16:36, Alexander Graf ha scritto:
With Michael's earlier patch in this series, the hwrng is accessible by
host userspace via /dev/hwrng, no?
Yes, but there's not token from user space that gets passed into the
kernel to check whether access is ok or not. So while QEMU may
On 02.10.2013, at 16:33, 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
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
On Wed, 2013-10-02 at 11:11 +0200, Alexander Graf wrote:
Right, and the difference for the patch in question is really whether
we handle in in kernel virtual mode or in QEMU, so the bulk of the
overhead (kicking threads out of guest context, switching MMU
context, etc) happens either way.
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
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
On Wed, 2013-10-02 at 16:08 +0200, Alexander Graf wrote:
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
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
On Wed, Oct 02, 2013 at 04:36:05PM +0200, Alexander Graf wrote:
On 02.10.2013, at 16:33, 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
On Thu, Oct 03, 2013 at 08:02:20AM +1000, Benjamin Herrenschmidt wrote:
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
On Thu, Oct 03, 2013 at 08:45:42AM +1000, Paul Mackerras wrote:
On Wed, Oct 02, 2013 at 04:36:05PM +0200, Alexander Graf wrote:
On 02.10.2013, at 16:33, Paolo Bonzini wrote:
Il 02/10/2013 16:08, Alexander Graf ha scritto:
The hwrng is accessible by host userspace via /dev/mem.
On Thu, Sep 26, 2013 at 11:06:59AM +0200, Paolo Bonzini wrote:
Il 26/09/2013 08:31, Michael Ellerman ha scritto:
Some powernv systems include a hwrng. Guests can access it via the
H_RANDOM hcall.
Is there any reason to do this in the kernel?
It's less code, and it's faster :)
It does
On Fri, Sep 27, 2013 at 07:45:45PM +0530, Anshuman Khandual wrote:
On 09/26/2013 12:01 PM, Michael Ellerman wrote:
+int powernv_hwrng_present(void)
+{
+ return __raw_get_cpu_var(powernv_rng) != NULL;
+}
+
static unsigned long rng_whiten(struct powernv_rng *rng, unsigned long val)
On Tue, Oct 01, 2013 at 06:34:26PM +1000, Michael Ellerman wrote:
On Thu, Sep 26, 2013 at 11:06:59AM +0200, Paolo Bonzini wrote:
Il 26/09/2013 08:31, Michael Ellerman ha scritto:
Some powernv systems include a hwrng. Guests can access it via the
H_RANDOM hcall.
Is there any reason to
On Tue, Oct 01, 2013 at 11:39:08AM +0300, Gleb Natapov wrote:
On Tue, Oct 01, 2013 at 06:34:26PM +1000, Michael Ellerman wrote:
On Thu, Sep 26, 2013 at 11:06:59AM +0200, Paolo Bonzini wrote:
Il 26/09/2013 08:31, Michael Ellerman ha scritto:
Some powernv systems include a hwrng. Guests
On Tue, 2013-10-01 at 11:39 +0300, Gleb Natapov wrote:
On Tue, Oct 01, 2013 at 06:34:26PM +1000, Michael Ellerman wrote:
On Thu, Sep 26, 2013 at 11:06:59AM +0200, Paolo Bonzini wrote:
Il 26/09/2013 08:31, Michael Ellerman ha scritto:
Some powernv systems include a hwrng. Guests can
Il 01/10/2013 10:34, Michael Ellerman ha scritto:
If you really want to have the hypercall, implementing it in QEMU means
that you can support it on all systems, in fact even when running
without KVM.
Sure, I can add a fallback to /dev/hwrng for full emulation.
The QEMU command line
On Tue, Oct 01, 2013 at 07:23:20PM +1000, Paul Mackerras wrote:
On Tue, Oct 01, 2013 at 11:39:08AM +0300, Gleb Natapov wrote:
On Tue, Oct 01, 2013 at 06:34:26PM +1000, Michael Ellerman wrote:
On Thu, Sep 26, 2013 at 11:06:59AM +0200, Paolo Bonzini wrote:
Il 26/09/2013 08:31, Michael
On 10/01/2013 11:23 AM, Paul Mackerras wrote:
On Tue, Oct 01, 2013 at 11:39:08AM +0300, Gleb Natapov wrote:
On Tue, Oct 01, 2013 at 06:34:26PM +1000, Michael Ellerman wrote:
On Thu, Sep 26, 2013 at 11:06:59AM +0200, Paolo Bonzini wrote:
Il 26/09/2013 08:31, Michael Ellerman ha scritto:
Some
Il 01/10/2013 11:38, Benjamin Herrenschmidt ha scritto:
So for the sake of that dogma you are going to make us do something that
is about 100 times slower ? (and possibly involves more lines of code)
If it's 100 times slower there is something else that's wrong. It's
most likely not 100 times
On Tue, 2013-10-01 at 13:19 +0200, Paolo Bonzini wrote:
Il 01/10/2013 11:38, Benjamin Herrenschmidt ha scritto:
So for the sake of that dogma you are going to make us do something that
is about 100 times slower ? (and possibly involves more lines of code)
If it's 100 times slower there is
On Tue, Oct 01, 2013 at 01:19:06PM +0200, Paolo Bonzini wrote:
Anyhow, I would like to know more about this hwrng and hypercall.
Does the hwrng return random numbers (like rdrand) or real entropy (like
rdseed that Intel will add in Broadwell)? What about the hypercall?
Well, firstly, your
On 09/26/2013 12:01 PM, Michael Ellerman wrote:
+int powernv_hwrng_present(void)
+{
+ return __raw_get_cpu_var(powernv_rng) != NULL;
+}
+
static unsigned long rng_whiten(struct powernv_rng *rng, unsigned long val)
{
unsigned long parity;
@@ -42,6 +48,17 @@ static unsigned long
Il 26/09/2013 08:31, Michael Ellerman ha scritto:
Some powernv systems include a hwrng. Guests can access it via the
H_RANDOM hcall.
We add a real mode implementation of H_RANDOM when a hwrng is found.
Userspace can detect the presence of the hwrng by quering the
KVM_CAP_PPC_HWRNG
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