Re: [Xen-devel] [v3 2/5] Qemu-Xen-vTPM: Xen frontend driver infrastructure

["Xu, Quan" <quan.xu@xxxxxxxxx>]

> -----Original Message-----
> From: Stefano Stabellini [mailto:stefano.stabellini@xxxxxxxxxxxxx]
> Sent: Tuesday, January 20, 2015 1:15 AM
> To: Xu, Quan
> Cc: qemu-devel@xxxxxxxxxx; xen-devel@xxxxxxxxxxxxx;
> stefano.stabellini@xxxxxxxxxxxxx
> Subject: Re: [v3 2/5] Qemu-Xen-vTPM: Xen frontend driver infrastructure
> 
> On Tue, 30 Dec 2014, Quan Xu wrote:
> > This patch adds infrastructure for xen front drivers living in qemu,
> > so drivers don't need to implement common stuff on their own.  It's
> > mostly xenbus management stuff: some functions to access XenStore,
> > setting up XenStore watches, callbacks on device discovery and state
> > changes, and handle event channel between the virtual machines.
> >
> > Call xen_fe_register() function to register XenDevOps, and make sure,
> > XenDevOps's flags is DEVOPS_FLAG_FE, which is flag bit to point out
> > the XenDevOps is Xen frontend.
> >
> > --Changes in v3:
> > -New xen_frontend.c file
> > -Move xenbus_switch_state() to xen_frontend.c -Move xen_stubdom_be()
> > to xenstore_fe_read_be_str() -Move *_stubdom_*() to *_fe_*()
> >
> > Signed-off-by: Quan Xu <quan.xu@xxxxxxxxx>
> > ---
> >  hw/xen/Makefile.objs         |   2 +-
> >  hw/xen/xen_backend.c         |  11 +-
> >  hw/xen/xen_frontend.c        | 323
> +++++++++++++++++++++++++++++++++++++++++++
> >  include/hw/xen/xen_backend.h |  14 ++
> >  4 files changed, 348 insertions(+), 2 deletions(-)  create mode
> > 100644 hw/xen/xen_frontend.c
> >
> > diff --git a/hw/xen/Makefile.objs b/hw/xen/Makefile.objs index
> > a0ca0aa..b0bb065 100644
> > --- a/hw/xen/Makefile.objs
> > +++ b/hw/xen/Makefile.objs
> > @@ -1,5 +1,5 @@
> >  # xen backend driver support
> > -common-obj-$(CONFIG_XEN_BACKEND) += xen_backend.o xen_devconfig.o
> > +common-obj-$(CONFIG_XEN_BACKEND) += xen_backend.o xen_devconfig.o
> > +xen_frontend.o
> >
> >  obj-$(CONFIG_XEN_PCI_PASSTHROUGH) += xen-host-pci-device.o
> >  obj-$(CONFIG_XEN_PCI_PASSTHROUGH) += xen_pt.o xen_pt_config_init.o
> > xen_pt_msi.o diff --git a/hw/xen/xen_backend.c b/hw/xen/xen_backend.c
> > index b2cb22b..ad6e324 100644
> > --- a/hw/xen/xen_backend.c
> > +++ b/hw/xen/xen_backend.c
> > @@ -275,7 +275,7 @@ static struct XenDevice *xen_be_get_xendev(const
> > char *type, int dom, int dev,
> >  /*
> >   * release xen backend device.
> >   */
> > -static struct XenDevice *xen_be_del_xendev(int dom, int dev)
> > +struct XenDevice *xen_be_del_xendev(int dom, int dev)
> >  {
> >      struct XenDevice *xendev, *xnext;
> >
> > @@ -681,6 +681,10 @@ static void xenstore_update(void *unused)
> >      if (sscanf(vec[XS_WATCH_TOKEN], "fe:%" PRIxPTR, &ptr) == 1) {
> >          xenstore_update_fe(vec[XS_WATCH_PATH], (void*)ptr);
> >      }
> > +    if (sscanf(vec[XS_WATCH_TOKEN], "stub:%" PRIxPTR ":%d:%" PRIxPTR,
> > +               &type, &dom, &ops) == 3) {
> > +        xenstore_fe_update(vec[XS_WATCH_PATH], (void *)type, dom,
> (void *)ops);
> > +    }
> 
> Why "stub:"? Where is it coming from?
> 
> I think that the xenstore_update function should be moved to a new file:
> we don't want xen_backend.c to be handling any frontend updates.
> Maybe you could create a new file, hw/xen/xen_pvdev.c?
> 

Stefano,
        I'd like to create hw/xen/xen_pvdev.c , include/hw/xen/ xen_pvdev.h and 
include/hw/xen/xen_frontend.h

include/hw/xen/ xen_pvdev.h is for 
struct XenDevOps{} and struct XenDevice {} definition and some other macro.

include/hw/xen/xen_frontend.h is for 
xen frontend interface, such as xen_fe_register() .etc

hw/xen/xen_pvdev.c is for 
some general parts of xen_backend/xen_frontend.
It includes xenstore_update function xendevs management, such as 
xen_qtail_insert_xendev(..),
xenstore_update(...) .etc.

do you agree with it?


Quan

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