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Date: Wed, 15 Aug 2012 12:39:55 +0000
From: KY Srinivasan <kys@...rosoft.com>
To: KY Srinivasan <kys@...rosoft.com>,
Greg KH <gregkh@...uxfoundation.org>
CC: "olaf@...fle.de" <olaf@...fle.de>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"virtualization@...ts.osdl.org" <virtualization@...ts.osdl.org>,
"apw@...onical.com" <apw@...onical.com>,
"devel@...uxdriverproject.org" <devel@...uxdriverproject.org>,
"ben@...adent.org.uk" <ben@...adent.org.uk>
Subject: RE: [PATCH V2 02/18] Drivers: hv: Add KVP definitions for IP
address injection
> -----Original Message-----
> From: devel-bounces@...uxdriverproject.org [mailto:devel-
> bounces@...uxdriverproject.org] On Behalf Of KY Srinivasan
> Sent: Monday, August 13, 2012 10:57 PM
> To: Greg KH
> Cc: olaf@...fle.de; linux-kernel@...r.kernel.org; virtualization@...ts.osdl.org;
> apw@...onical.com; devel@...uxdriverproject.org; ben@...adent.org.uk
> Subject: RE: [PATCH V2 02/18] Drivers: hv: Add KVP definitions for IP address
> injection
>
>
>
> > -----Original Message-----
> > From: Greg KH [mailto:gregkh@...uxfoundation.org]
> > Sent: Monday, August 13, 2012 9:38 PM
> > To: KY Srinivasan
> > Cc: linux-kernel@...r.kernel.org; devel@...uxdriverproject.org;
> > virtualization@...ts.osdl.org; olaf@...fle.de; apw@...onical.com;
> > ben@...adent.org.uk
> > Subject: Re: [PATCH V2 02/18] Drivers: hv: Add KVP definitions for IP address
> > injection
> >
> > On Mon, Aug 13, 2012 at 10:06:51AM -0700, K. Y. Srinivasan wrote:
> > > Add the necessary definitions for supporting the IP injection functionality.
> > >
> > > Signed-off-by: K. Y. Srinivasan <kys@...rosoft.com>
> > > Reviewed-by: Haiyang Zhang <haiyangz@...rosoft.com>
> > > Reviewed-by: Olaf Hering <olaf@...fle.de>
> > > Reviewed-by: Ben Hutchings <ben@...adent.org.uk>
> > > ---
> > > drivers/hv/hv_util.c | 4 +-
> > > include/linux/hyperv.h | 76
> > ++++++++++++++++++++++++++++++++++++++++++++-
> > > tools/hv/hv_kvp_daemon.c | 2 +-
> > > 3 files changed, 77 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/drivers/hv/hv_util.c b/drivers/hv/hv_util.c
> > > index d3ac6a4..a0667de 100644
> > > --- a/drivers/hv/hv_util.c
> > > +++ b/drivers/hv/hv_util.c
> > > @@ -263,7 +263,7 @@ static int util_probe(struct hv_device *dev,
> > > (struct hv_util_service *)dev_id->driver_data;
> > > int ret;
> > >
> > > - srv->recv_buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
> > > + srv->recv_buffer = kmalloc(PAGE_SIZE * 2, GFP_KERNEL);
> > > if (!srv->recv_buffer)
> > > return -ENOMEM;
> > > if (srv->util_init) {
> > > @@ -274,7 +274,7 @@ static int util_probe(struct hv_device *dev,
> > > }
> > > }
> > >
> > > - ret = vmbus_open(dev->channel, 2 * PAGE_SIZE, 2 * PAGE_SIZE, NULL,
> > 0,
> > > + ret = vmbus_open(dev->channel, 4 * PAGE_SIZE, 4 * PAGE_SIZE, NULL,
> > 0,
> > > srv->util_cb, dev->channel);
> > > if (ret)
> > > goto error;
> > > diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
> > > index 68ed7f7..11afc4e 100644
> > > --- a/include/linux/hyperv.h
> > > +++ b/include/linux/hyperv.h
> > > @@ -122,12 +122,53 @@
> > > #define REG_U32 4
> > > #define REG_U64 8
> > >
> > > +/*
> > > + * As we look at expanding the KVP functionality to include
> > > + * IP injection functionality, we need to maintain binary
> > > + * compatibility with older daemons.
> > > + *
> > > + * The KVP opcodes are defined by the host and it was unfortunate
> > > + * that I chose to treat the registration operation as part of the
> > > + * KVP operations defined by the host.
> > > + * Here is the level of compatibility
> > > + * (between the user level daemon and the kernel KVP driver) that we
> > > + * will implement:
> > > + *
> > > + * An older daemon will always be supported on a newer driver.
> > > + * A given user level daemon will require a minimal version of the
> > > + * kernel driver.
> > > + * If we cannot handle the version differences, we will fail gracefully
> > > + * (this can happen when we have a user level daemon that is more
> > > + * advanced than the KVP driver.
> > > + *
> > > + * We will use values used in this handshake for determining if we have
> > > + * workable user level daemon and the kernel driver. We begin by taking the
> > > + * registration opcode out of the KVP opcode namespace. We will however,
> > > + * maintain compatibility with the existing user-level daemon code.
> > > + */
> > > +
> > > +/*
> > > + * Daemon code not supporting IP injection (legacy daemon).
> > > + */
> > > +
> > > +#define KVP_OP_REGISTER 4
> >
> > Huh?
> >
> > > +/*
> > > + * Daemon code supporting IP injection.
> > > + * The KVP opcode field is used to communicate the
> > > + * registration information; so define a namespace that
> > > + * will be distinct from the host defined KVP opcode.
> > > + */
> > > +
> > > +#define KVP_OP_REGISTER1 100
> > > +
> > > enum hv_kvp_exchg_op {
> > > KVP_OP_GET = 0,
> > > KVP_OP_SET,
> > > KVP_OP_DELETE,
> > > KVP_OP_ENUMERATE,
> > > - KVP_OP_REGISTER,
> > > + KVP_OP_GET_IP_INFO,
> > > + KVP_OP_SET_IP_INFO,
> >
> > So you overloaded the command and somehow think that is ok? How is that
> > supposed to work? Why not just always keep it there, but fail if it is
> > called as you know you have a mismatch?
> >
> > Otherwise, again, you just broke older tools on a newer kernel.
> >
> > Or am I missing something here?
>
> Greg,
>
> The registration operation occurs when the daemon first starts up. I should have
> established
> a distinct namespace for the daemon versions that would not overlap with the
> host
> defined KVP operations initially. Unfortunately when I first implemented KVP, I
> did not know
> about the new KVP verbs and so selected a value that ended up colliding with the
> new KVP
> operations. To maintain compatibility with older daemons, I have to support this
> old registration
> value, which is what you are seeing here. Since the initial driver/daemon
> handshake phase does
> not overlap with the normal functioning of the KVP stack, we can use the old
> daemon
> registration value to distinguish that the daemon does not support IP injection.
> The current
> implementation does support a compatible environment for older daemons.
>
Greg,
I hope this explanation is satisfactory. If there are other issues that you would
want me to address before this patch set can be accepted, let me know and I will
address them right away.
Regards,
K. Y
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