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Re: [Xen-devel] [PATCH 2/4] Qemu-Xen-vTPM: Register Xen stubdom vTPM frontend driver



On Tue, 4 Nov 2014, Xu, Quan wrote:
> > -----Original Message-----
> > From: Stefano Stabellini [mailto:stefano.stabellini@xxxxxxxxxxxxx]
> > Sent: Monday, November 03, 2014 7:54 PM
> > To: Xu, Quan
> > Cc: qemu-devel@xxxxxxxxxx; xen-devel@xxxxxxxxxxxxx;
> > stefano.stabellini@xxxxxxxxxxxxx
> > Subject: Re: [PATCH 2/4] Qemu-Xen-vTPM: Register Xen stubdom vTPM
> > frontend driver
> > 
> > On Sun, 2 Nov 2014, Quan Xu wrote:
> > > This drvier transfers any request/repond between TPM xenstubdoms
> > > driver and Xen vTPM stubdom, and facilitates communications between
> > > Xen vTPM stubdom domain and vTPM xenstubdoms driver
> > >
> > > Signed-off-by: Quan Xu <quan.xu@xxxxxxxxx>
> > 
> > Please describe what changes did make to xen_backend.c and why.
> > The commit message should contains info on all the changes made by the
> > patch below.
> > 
>       
> Thanks Stefano. 
> one more day, I will explain in detail what changes did make to xen_backend.c 
> and why. 
> The following 2 sections are introduction and architecture. 
> 
> > Please also describe what is the "Xen vTPM stubdom", what is the
> > "vTPM xenstubdoms driver" and how the communicate with each others.
> > 
> 
> 
> Add 2 parts for detailed descriptions, introduction and architecture.  
> 
> *INTRODUCTION*
> 
> The goal of virtual Trusted Platform Module (vTPM) is to provide a TPM 
> functionality
> to virtual machines (Fedora, Ubuntu, Redhat, Windows .etc). This allows 
> programs to
> interact with a TPM in a virtual machine the same way they interact with a 
> TPM on the
> physical system. Each virtual machine gets its own unique, emulated, software 
> TPM.
> Each major component of vTPM is implemented as a stubdom, providing secure 
> separation
> guaranteed by the hypervisor.
> The vTPM stubdom is a Xen mini-OS domain that emulates a TPM for the virtual 
> machine
> to use. It is a small wrapper around the Berlios TPM emulator. TPM commands 
> are passed
> from mini-os TPM backend driver.
> This patch series are only the Qemu part to enable Xen stubdom vTPM for HVM 
> virtual
> machine.
> ===========
> 
> *ARCHITECTURE*
> 
> The architecture of stubdom vTPM for HVM virtual machine:
> 
>             +--------------------+
>             | Windows/Linux DomU | ...
>             |        |  ^        |
>             |        v  |        |
>             |  Qemu tpm1.2 Tis   |
>             |        |  ^        |
>             |        v  |        |
>             |        vTPM        |
>             | XenStubdoms driver |  (new ..)
>             +--------------------+
>                      |  ^
>                      v  |
>             +--------------------+
>             |  xen_vtpmdev_ops   |  (new ..)
>             +--------------------+
>                      |  ^
>                      v  |
>             +--------------------+
>             |  mini-os/tpmback   |
>             |        |  ^        |
>             |        v  |        |
>             |   vTPM stubdom     | ...
>             |        |  ^        |
>             |        v  |        |
>             |  mini-os/tpmfront  |
>             +--------------------+
>                      |  ^
>                      v  |
>             +--------------------+
>             |  mini-os/tpmback   |
>             |        |  ^        |
>             |        v  |        |
>             |  vtpmmgr stubdom   |
>             |        |  ^        |
>             |        v  |        |
>             |  mini-os/tpm_tis   |
>             +--------------------+
>                      |  ^
>                      v  |
>             +--------------------+
>             |    Hardware TPM    |
>             +--------------------+
> 
> 
> * Windows/Linux DomU:
>     The HVM based guest that wants to use a vTPM. There may be
>     more than one of these.
> 
>  * Qemu tpm1.2 Tis:
>     Implementation of the tpm1.2 Tis interface for HVM virtual
>     machines. It is Qemu emulation device.

It looks like you are running upstream QEMU within a Mini-OS stubdom?
If so, where are the patches to do that? As far as I know upstream QEMU
doesn't run on Mini-OS. Or maybe it is a Linux stubdom? Either way, it
is not clear.


>  * vTPM xenstubdoms driver:
>     Similar to a TPM passthrough backend driver, it is a new TPM
>     backend for emulated TPM TIS interface. This driver provides
>     vTPM initialization and sending data and commends to a Xen
>     vTPM stubdom.

This is patch #3, right? It is basically the internal QEMU "glue" to
connect the tpm emulator to xen_vtpmdev_ops, correct?


>  * xen_vtpmdev_ops:
>     Register Xen stubdom vTPM backend, and transfer any request/
>     repond between TPM xenstubdoms driver and Xen vTPM stubdom.
>     Facilitate communications between Xen vTPM stubdom and vTPM
>     xenstubdoms driver.
 
It looks like this correspond to patch #2? If so, this is a regular Xen
PV frontend, living in QEMU? It requires the gntalloc device so I guess
it is supposed to run on Linux. In that case is it just a tpmfront
implementation in QEMU?

If you are running it on Linux, we might need to introduce Linux based
stundoms to the Xen build system.


>  * mini-os/tpmback:
>     Mini-os TPM backend driver. The Linux frontend driver connects
>     to this backend driver to facilitate communications between the
>     Linux DomU and its vTPM. This driver is also used by vtpmmgr
>     stubdom to communicate with vTPM stubdom.
> 
>  * vTPM stubdom:
>     A mini-os stub domain that implements a vTPM. There is a
>     one to one mapping between running vTPM stubdom instances and
>     logical vTPMs on the system. The vTPM Platform Configuration
>     Registers (PCRs) are all initialized to zero.
>
>  * mini-os/tpmfront:
>     Mini-os TPM frontend driver. The vTPM mini-os domain vTPM
>     stubdom uses this driver to communicate with vtpmmgr-stubdom.
>     This driver could also be used separately to implement a mini-os
>     domain that wishes to use a vTPM of its own.
>
>  * vtpmmgr stubdom:
>     A mini-os domain that implements the vTPM manager. There is only
>     one vTPM manager and it should be running during the entire lifetime
>     of the machine. vtpmmgr domain securely stores encryption keys for
>     each of the vTPMs and accesses to the hardware TPM to get the root of
>     trust for the entire system.
> 
>  * mini-os/tpm_tis:
>     Mini-os TPM version 1.2 TPM Interface Specification (TIS) driver.
>     This driver used by vtpmmgr-stubdom to talk directly to the hardware
>     TPM. Communication is facilitated by mapping hardware memory pages
>     into vtpmmgr stubdom.
 
Are all the Mini-OS component upstream, or do we need patches?


>  * Hardware TPM:
>     The physical TPM 1.2 that is soldered onto the motherboard.
> 
> ===========
> 
> 
> 
> > Where does the vTPM backend lives?
> The vTPM backend lives in Xen vTPM stubdom (Xen Mini-os)

Thanks for the explanation, it is a bit clearer now.


> > 
> > 
> > >  hw/xen/Makefile.objs         |   1 +
> > >  hw/xen/xen_backend.c         | 182 ++++++++++++++++++++++-
> > >  hw/xen/xen_stubdom_vtpm.c    | 333
> > +++++++++++++++++++++++++++++++++++++++++++
> > >  include/hw/xen/xen_backend.h |  11 ++
> > >  include/hw/xen/xen_common.h  |   6 +
> > >  xen-hvm.c                    |  13 ++
> > >  6 files changed, 544 insertions(+), 2 deletions(-)
> > >  create mode 100644 hw/xen/xen_stubdom_vtpm.c
> > >
> > > diff --git a/hw/xen/Makefile.objs b/hw/xen/Makefile.objs
> > > index a0ca0aa..724df8d 100644
> > > --- a/hw/xen/Makefile.objs
> > > +++ b/hw/xen/Makefile.objs
> > > @@ -1,5 +1,6 @@
> > >  # xen backend driver support
> > >  common-obj-$(CONFIG_XEN_BACKEND) += xen_backend.o
> > xen_devconfig.o
> > > +common-obj-$(CONFIG_TPM_XENSTUBDOMS) += xen_stubdom_vtpm.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..45a5778 100644
> > > --- a/hw/xen/xen_backend.c
> > > +++ b/hw/xen/xen_backend.c
> > > @@ -194,6 +194,32 @@ int xen_be_set_state(struct XenDevice *xendev,
> > enum xenbus_state state)
> > >      return 0;
> > >  }
> > >
> > > +/*get stubdom backend*/
> > > +static char *xen_stubdom_be(const char *type, int dom, int dev)
> > > +{
> > > +    char *val, *domu;
> > > +    char path[XEN_BUFSIZE];
> > > +    unsigned int len, ival;
> > > +
> > > +    /*front domu*/
> > > +    domu = xs_get_domain_path(xenstore, dom);
> > > +    snprintf(path, sizeof(path), "%s/device/%s/%d/backend-id",
> > > +             domu, type, dev);
> > > +    g_free(domu);
> > > +
> > > +    val = xs_read(xenstore, 0, path, &len);
> > > +    if (!val || 1 != sscanf(val, "%d", &ival)) {
> > > +        g_free(val);
> > > +        return NULL;
> > > +    }
> > > +    g_free(val);
> > > +
> > > +    /*backend domu*/
> > > +    domu = xs_get_domain_path(xenstore, ival);
> > > +
> > > +    return domu;
> > > +}
> > > +
> > >  /* ------------------------------------------------------------- */
> > >
> > >  struct XenDevice *xen_be_find_xendev(const char *type, int dom, int
> > dev)
> > > @@ -222,6 +248,7 @@ static struct XenDevice *xen_be_get_xendev(const
> > char *type, int dom, int dev,
> > >                                             struct XenDevOps *ops)
> > >  {
> > >      struct XenDevice *xendev;
> > > +    char *stub;
> > >
> > >      xendev = xen_be_find_xendev(type, dom, dev);
> > >      if (xendev) {
> > > @@ -235,8 +262,15 @@ static struct XenDevice
> > *xen_be_get_xendev(const char *type, int dom, int dev,
> > >      xendev->dev   = dev;
> > >      xendev->ops   = ops;
> > >
> > > -    snprintf(xendev->be, sizeof(xendev->be), "backend/%s/%d/%d",
> > > -             xendev->type, xendev->dom, xendev->dev);
> > > +    if (ops->flags & DEVOPS_FLAG_STUBDOM_BE) {
> > > +        stub = xen_stubdom_be(xendev->type, xendev->dom,
> > xendev->dev);
> > > +        snprintf(xendev->be, sizeof(xendev->be),
> > "%s/backend/%s/%d/%d",
> > > +                 stub, xendev->type, xendev->dom, xendev->dev);
> > > +        g_free(stub);
> > > +    } else {
> > > +        snprintf(xendev->be, sizeof(xendev->be), "backend/%s/%d/%d",
> > > +                 xendev->type, xendev->dom, xendev->dev);
> > > +    }
> > >      snprintf(xendev->name, sizeof(xendev->name), "%s-%d",
> > >               xendev->type, xendev->dev);
> > >
> > > @@ -611,6 +645,47 @@ static int xenstore_scan(const char *type, int
> > dom, struct XenDevOps *ops)
> > >      return 0;
> > >  }
> > >
> > > +static void stubdom_update_be(char *watch, char *type, int dom,
> > > +                              struct XenDevOps *ops)
> > > +{
> > > +    struct XenDevice *xendev;
> > > +    char path[XEN_BUFSIZE];
> > > +    char *ptr, *bepath;
> > > +    unsigned int len, dev;
> > > +
> > > +    if (!(ops->flags & DEVOPS_FLAG_STUBDOM_BE)) {
> > > +        return;
> > > +    }
> > > +
> > > +    len = snprintf(path, sizeof(path), "backend/%s/%d", type, dom);
> > > +    ptr = strstr(watch, path);
> > > +    if (ptr == NULL) {
> > > +        return;
> > > +    }
> > > +
> > > +    if (sscanf(ptr+len, "/%u/%255s", &dev, path) != 2) {
> > > +        strcpy(path, "");
> > > +        if (sscanf(ptr+len, "/%u", &dev) != 1) {
> > > +            dev = -1;
> > > +        }
> > > +    }
> > > +
> > > +    if (dev == -1) {
> > > +        return;
> > > +    }
> > > +
> > > +    xendev = xen_be_get_xendev(type, dom, dev, ops);
> > > +    if (xendev != NULL) {
> > > +        bepath = xs_read(xenstore, 0, xendev->be, &len);
> > > +        if (bepath == NULL) {
> > > +            xen_be_del_xendev(dom, dev);
> > > +        } else {
> > > +            free(bepath);
> > > +            xen_be_backend_changed(xendev, path);
> > > +        }
> > > +    }
> > > +}
> > > +
> > >  static void xenstore_update_be(char *watch, char *type, int dom,
> > >                                 struct XenDevOps *ops)
> > >  {
> > > @@ -681,6 +756,10 @@ 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) {
> > > +        stubdom_update_be(vec[XS_WATCH_PATH], (void *)type, dom,
> > (void *)ops);
> > > +    }
> > >
> > >  cleanup:
> > >      free(vec);
> > > @@ -732,11 +811,74 @@ err:
> > >      return -1;
> > >  }
> > >
> > > +int xen_vtpm_register(struct XenDevOps *ops)
> > > +{
> > > +    struct XenDevice *xendev;
> > > +    char path[XEN_BUFSIZE], token[XEN_BUFSIZE];
> > > +    char *domu;
> > > +    unsigned int cdev, j, rc;
> > > +    const char *type = "vtpm";
> > > +    char **dev = NULL;
> > > +
> > > +    /*front domu*/
> > > +    domu = xs_get_domain_path(xenstore, xen_domid);
> > > +    snprintf(path, sizeof(path), "%s/device/%s",
> > > +             domu, type);
> > > +    free(domu);
> > > +    dev = xs_directory(xenstore, 0, path, &cdev);
> > > +    if (dev == NULL) {
> > > +        return 0;
> > > +    }
> > > +
> > > +    for (j = 0; j < cdev; j++) {
> > > +        xendev = xen_be_get_xendev(type, xen_domid, atoi(dev[j]),
> > ops);
> > > +        if (xendev == NULL) {
> > > +            xen_be_printf(xendev, 0, "xen_vtpm_register xendev is
> > NULL.\n");
> > > +            continue;
> > > +        }
> > > +
> > > +        if (xendev->ops->initialise) {
> > > +            rc = xendev->ops->initialise(xendev);
> > > +
> > > +            /*if initialise failed, delete it*/
> > > +            if (rc != 0) {
> > > +                xen_be_del_xendev(xen_domid, atoi(dev[j]));
> > > +                continue;
> > > +            }
> > > +        }
> > > +
> > > +        /*setup watch*/
> > > +        snprintf(token, sizeof(token), "stub:%p:%d:%p",
> > > +                 type, xen_domid, xendev->ops);
> > > +        if (!xs_watch(xenstore, xendev->be, token)) {
> > > +            xen_be_printf(xendev, 0, "xen_vtpm_register xs_watch
> > failed.\n");
> > > +            return -1;
> > > +        }
> > > +    }
> > > +
> > > +    free(dev);
> > > +    return 0;
> > > +}
> > 
> > What does this function do? I sholdn't need  to guess from the code, I
> > should be able to tell from the patch description.
> > 
> > 
> > >  int xen_be_register(const char *type, struct XenDevOps *ops)
> > >  {
> > >      return xenstore_scan(type, xen_domid, ops);
> > >  }
> > >
> > > +int xen_be_alloc_unbound(struct XenDevice *xendev, int dom, int
> > remote_dom)
> > > +{
> > > +    xendev->local_port =
> > xc_evtchn_bind_unbound_port(xendev->evtchndev,
> > > +
> > remote_dom);
> > > +    if (xendev->local_port == -1) {
> > > +        xen_be_printf(xendev, 0, "xc_evtchn_alloc_unbound failed\n");
> > > +        return -1;
> > > +    }
> > > +    xen_be_printf(xendev, 2, "bind evtchn port %d\n",
> > xendev->local_port);
> > > +    qemu_set_fd_handler(xc_evtchn_fd(xendev->evtchndev),
> > > +                        xen_be_evtchn_event, NULL, xendev);
> > > +    return 0;
> > > +}
> > > +
> > >  int xen_be_bind_evtchn(struct XenDevice *xendev)
> > >  {
> > >      if (xendev->local_port != -1) {
> > > @@ -770,6 +912,42 @@ int xen_be_send_notify(struct XenDevice
> > *xendev)
> > >      return xc_evtchn_notify(xendev->evtchndev, xendev->local_port);
> > >  }
> > >
> > > +int xen_vtpm_send(unsigned char *buf, size_t count)
> > > +{
> > > +    struct XenDevice *xendev;
> > > +    int rc = -1;
> > > +
> > > +    xendev = xen_be_find_xendev("vtpm", xen_domid, 0);
> > > +    if (xendev == NULL) {
> > > +        xen_be_printf(xendev, 0, "Con not find vtpm device\n");
> > > +        return -1;
> > > +    }
> > > +
> > > +    if (xendev->ops->send) {
> > > +        rc = xendev->ops->send(xendev, buf, count);
> > > +    }
> > > +
> > > +    return rc;
> > > +}
> > > +
> > > +int xen_vtpm_recv(unsigned char *buf, size_t *count)
> > > +{
> > > +    struct XenDevice *xendev;
> > > +    int rc = -1;
> > > +
> > > +    xendev = xen_be_find_xendev("vtpm", xen_domid, 0);
> > > +    if (xendev == NULL) {
> > > +        xen_be_printf(xendev, 0, "Con not find vtpm device\n");
> > > +        return -1;
> > > +    }
> > > +
> > > +    if (xendev->ops->recv) {
> > > +        xendev->ops->recv(xendev, buf, count);
> > > +    }
> > > +
> > > +    return rc;
> > > +}
> > 
> > xen_backend.c is supposed to be generic, so stubdom functions might be
> > OK but vtpm specific functions should not be here.
> > 
> > 
> > >  /*
> > >   * msg_level:
> > >   *  0 == errors (stderr + logfile).
> > > diff --git a/hw/xen/xen_stubdom_vtpm.c b/hw/xen/xen_stubdom_vtpm.c
> > > new file mode 100644
> > > index 0000000..0d740c1
> > > --- /dev/null
> > > +++ b/hw/xen/xen_stubdom_vtpm.c
> > > @@ -0,0 +1,333 @@
> > > +/*
> > > + * Connect to Xen vTPM stubdom domain
> > > + *
> > > + *  Copyright (c) 2014 Intel Corporation
> > > + *  Authors:
> > > + *    Quan Xu <quan.xu@xxxxxxxxx>
> > > + *
> > > + * This library is free software; you can redistribute it and/or
> > > + * modify it under the terms of the GNU Lesser General Public
> > > + * License as published by the Free Software Foundation; either
> > > + * version 2 of the License, or (at your option) any later version.
> > > + *
> > > + * This library is distributed in the hope that it will be useful,
> > > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> > GNU
> > > + * Lesser General Public License for more details.
> > > + *
> > > + * You should have received a copy of the GNU Lesser General Public
> > > + * License along with this library; if not, see
> > <http://www.gnu.org/licenses/>
> > > + */
> > > +
> > > +#include <stdio.h>
> > > +#include <stdlib.h>
> > > +#include <stdarg.h>
> > > +#include <string.h>
> > > +#include <unistd.h>
> > > +#include <signal.h>
> > > +#include <inttypes.h>
> > > +#include <time.h>
> > > +#include <fcntl.h>
> > > +#include <errno.h>
> > > +#include <sys/ioctl.h>
> > > +#include <sys/types.h>
> > > +#include <sys/stat.h>
> > > +#include <sys/mman.h>
> > > +#include <sys/uio.h>
> > > +
> > > +#include "hw/hw.h"
> > > +#include "block/aio.h"
> > > +#include "hw/xen/xen_backend.h"
> > > +
> > > +enum tpmif_state {
> > > +    TPMIF_STATE_IDLE,        /* no contents / vTPM idle / cancel
> > complete */
> > > +    TPMIF_STATE_SUBMIT,      /* request ready / vTPM working */
> > > +    TPMIF_STATE_FINISH,      /* response ready / vTPM idle */
> > > +    TPMIF_STATE_CANCEL,      /* cancel requested / vTPM working */
> > > +};
> > > +
> > > +static AioContext *vtpm_aio_ctx;
> > > +
> > > +enum status_bits {
> > > +    VTPM_STATUS_RUNNING  = 0x1,
> > > +    VTPM_STATUS_IDLE     = 0x2,
> > > +    VTPM_STATUS_RESULT   = 0x4,
> > > +    VTPM_STATUS_CANCELED = 0x8,
> > > +};
> > > +
> > > +struct tpmif_shared_page {
> > > +    uint32_t length;         /* request/response length in bytes */
> > > +
> > > +    uint8_t  state;           /* enum tpmif_state */
> > > +    uint8_t  locality;        /* for the current request */
> > > +    uint8_t  pad;             /* should be zero */
> > > +
> > > +    uint8_t  nr_extra_pages;  /* extra pages for long packets; may be
> > zero */
> > > +    uint32_t extra_pages[0]; /* grant IDs; length is actually
> > nr_extra_pages */
> > > +};
> > > +
> > > +struct QEMUBH {
> > > +    AioContext *ctx;
> > > +    QEMUBHFunc *cb;
> > > +    void *opaque;
> > > +    QEMUBH *next;
> > > +    bool scheduled;
> > > +    bool idle;
> > > +    bool deleted;
> > > +};
> > > +
> > > +struct XenVtpmDev {
> > > +    struct XenDevice xendev;  /* must be first */
> > > +    struct           tpmif_shared_page *shr;
> > > +    xc_gntshr        *xen_xcs;
> > > +    int              ring_ref;
> > > +    int              bedomid;
> > > +    QEMUBH           *sr_bh;
> > > +};
> > > +
> > > +static uint8_t vtpm_status(struct XenVtpmDev *vtpmdev)
> > > +{
> > > +    switch (vtpmdev->shr->state) {
> > > +    case TPMIF_STATE_IDLE:
> > > +    case TPMIF_STATE_FINISH:
> > > +        return VTPM_STATUS_IDLE;
> > > +    case TPMIF_STATE_SUBMIT:
> > > +    case TPMIF_STATE_CANCEL:
> > > +        return VTPM_STATUS_RUNNING;
> > > +    default:
> > > +        return 0;
> > > +    }
> > > +}
> > > +
> > > +static int xenbus_switch_state(struct XenDevice *xendev, enum
> > xenbus_state xbus)
> > > +{
> > > +    xs_transaction_t xbt = XBT_NULL;
> > > +
> > > +    if (xendev->fe_state == xbus) {
> > > +        return 0;
> > > +    }
> > > +
> > > +    xendev->fe_state = xbus;
> > > +
> > > +retry_transaction:
> > > +    xbt = xs_transaction_start(xenstore);
> > > +    if (xbt == XBT_NULL) {
> > > +        goto abort_transaction;
> > > +    }
> > > +
> > > +    if (xenstore_write_int(xendev->fe, "state", xbus)) {
> > > +        goto abort_transaction;
> > > +    }
> > > +
> > > +    if (!xs_transaction_end(xenstore, xbt, 0)) {
> > > +        if (errno == EAGAIN) {
> > > +            goto retry_transaction;
> > > +        }
> > > +    }
> > > +
> > > +    return 0;
> > > +
> > > +abort_transaction:
> > > +    xs_transaction_end(xenstore, xbt, 1);
> > > +    return -1;
> > > +}
> > > +
> > > +static int vtpm_aio_wait(QEMUBH *qbh)
> > > +{
> > > +    return aio_poll(qbh->ctx, true);
> > > +}
> > > +
> > > +static void sr_bh_handler(void *opaque)
> > > +{
> > > +}
> > > +
> > > +static int vtpm_recv(struct XenDevice *xendev, uint8_t* buf, size_t
> > *count)
> > > +{
> > > +    struct XenVtpmDev *vtpmdev = container_of(xendev, struct
> > XenVtpmDev,
> > > +                                              xendev);
> > > +    struct tpmif_shared_page *shr = vtpmdev->shr;
> > > +    unsigned int offset;
> > > +
> > > +    if (shr->state == TPMIF_STATE_IDLE) {
> > > +        return -ECANCELED;
> > > +    }
> > > +
> > > +    while (vtpm_status(vtpmdev) != VTPM_STATUS_IDLE) {
> > > +        vtpm_aio_wait(vtpmdev->sr_bh);
> > > +    }
> > > +
> > > +    offset = sizeof(*shr) + 4*shr->nr_extra_pages;
> > > +    memcpy(buf, offset + (uint8_t *)shr, shr->length);
> > > +    *count = shr->length;
> > > +
> > > +    return 0;
> > > +}
> > > +
> > > +static int vtpm_send(struct XenDevice *xendev, uint8_t* buf, size_t
> > count)
> > > +{
> > > +    struct XenVtpmDev *vtpmdev = container_of(xendev, struct
> > XenVtpmDev,
> > > +                                              xendev);
> > > +    struct tpmif_shared_page *shr = vtpmdev->shr;
> > > +    unsigned int offset = sizeof(*shr) + 4*shr->nr_extra_pages;
> > > +
> > > +    while (vtpm_status(vtpmdev) != VTPM_STATUS_IDLE) {
> > > +        vtpm_aio_wait(vtpmdev->sr_bh);
> > > +    }
> > > +
> > > +    memcpy(offset + (uint8_t *)shr, buf, count);
> > > +    shr->length = count;
> > > +    barrier();
> > > +    shr->state = TPMIF_STATE_SUBMIT;
> > > +    xen_wmb();
> > > +    xen_be_send_notify(&vtpmdev->xendev);
> > > +
> > > +    while (vtpm_status(vtpmdev) != VTPM_STATUS_IDLE) {
> > > +        vtpm_aio_wait(vtpmdev->sr_bh);
> > > +    }
> > > +
> > > +    return count;
> > > +}
> > > +
> > > +static int vtpm_initialise(struct XenDevice *xendev)
> > > +{
> > > +    struct XenVtpmDev *vtpmdev = container_of(xendev, struct
> > XenVtpmDev,
> > > +                                              xendev);
> > > +    xs_transaction_t xbt = XBT_NULL;
> > > +    unsigned int ring_ref;
> > > +
> > > +    vtpmdev->xendev.fe = xenstore_read_be_str(&vtpmdev->xendev,
> > "frontend");
> > > +    if (vtpmdev->xendev.fe == NULL) {
> > > +        return -1;
> > > +    }
> > > +
> > > +    /* Get backend domid */
> > > +    if (xenstore_read_fe_int(&vtpmdev->xendev, "backend-id",
> > > +                             &vtpmdev->bedomid)) {
> > > +        return -1;
> > > +    }
> > > +
> > > +    /*alloc share page*/
> > > +    vtpmdev->shr = xc_gntshr_share_pages(vtpmdev->xen_xcs,
> > vtpmdev->bedomid, 1,
> > > +                                         &ring_ref,
> > PROT_READ|PROT_WRITE);
> > > +    vtpmdev->ring_ref = ring_ref;
> > > +    if (vtpmdev->shr == NULL) {
> > > +        return -1;
> > > +    }
> > > +
> > > +    /*Create event channel */
> > > +    if (xen_be_alloc_unbound(&vtpmdev->xendev, 0,
> > vtpmdev->bedomid)) {
> > > +        xc_gntshr_munmap(vtpmdev->xen_xcs, vtpmdev->shr, 1);
> > > +        return -1;
> > > +    }
> > > +
> > > +    xc_evtchn_unmask(vtpmdev->xendev.evtchndev,
> > > +                     vtpmdev->xendev.local_port);
> > > +
> > > +again:
> > > +    xbt = xs_transaction_start(xenstore);
> > > +    if (xbt == XBT_NULL) {
> > > +        goto abort_transaction;
> > > +    }
> > > +
> > > +    if (xenstore_write_int(vtpmdev->xendev.fe, "ring-ref",
> > > +                           vtpmdev->ring_ref)) {
> > > +        goto abort_transaction;
> > > +    }
> > > +
> > > +    if (xenstore_write_int(vtpmdev->xendev.fe, "event-channel",
> > > +                           vtpmdev->xendev.local_port)) {
> > > +        goto abort_transaction;
> > > +    }
> > > +
> > > +    /* Publish protocol v2 feature */
> > > +    if (xenstore_write_int(vtpmdev->xendev.fe, "feature-protocol-v2", 1))
> > {
> > > +        goto abort_transaction;
> > > +    }
> > > +
> > > +    if (!xs_transaction_end(xenstore, xbt, 0)) {
> > > +        if (errno == EAGAIN) {
> > > +            goto again;
> > > +        }
> > > +    }
> > > +    /* Tell vtpm backend that we are ready */
> > > +    xenbus_switch_state(&vtpmdev->xendev, XenbusStateInitialised);
> > > +
> > > +    return 0;
> > > +
> > > +abort_transaction:
> > > +    xc_gntshr_munmap(vtpmdev->xen_xcs, vtpmdev->shr, 1);
> > > +    xs_transaction_end(xenstore, xbt, 1);
> > > +    return -1;
> > > +}
> > > +
> > > +static void vtpm_backend_changed(struct XenDevice *xendev, const char
> > *node)
> > > +{
> > > +    struct XenVtpmDev *vtpmdev = container_of(xendev, struct
> > XenVtpmDev,
> > > +                                              xendev);
> > > +    int be_state;
> > > +
> > > +    if (strcmp(node, "state") == 0) {
> > > +        xenstore_read_be_int(&vtpmdev->xendev, node, &be_state);
> > > +        switch (be_state) {
> > > +        case XenbusStateConnected:
> > > +            /*TODO*/
> > > +            break;
> > > +        case XenbusStateClosing:
> > > +        case XenbusStateClosed:
> > > +            xenbus_switch_state(&vtpmdev->xendev,
> > XenbusStateClosing);
> > > +            break;
> > > +        default:
> > > +            break;
> > > +        }
> > > +    }
> > > +}
> > > +
> > > +static int vtpm_free(struct XenDevice *xendev)
> > > +{
> > > +    struct XenVtpmDev *vtpmdev = container_of(xendev, struct
> > XenVtpmDev,
> > > +                                              xendev);
> > > +    QEMUBH *qbh = vtpmdev->sr_bh;
> > > +
> > > +    aio_poll(qbh->ctx, false);
> > > +    qemu_bh_delete(vtpmdev->sr_bh);
> > > +    if (vtpmdev->shr) {
> > > +        xc_gntshr_munmap(vtpmdev->xen_xcs, vtpmdev->shr, 1);
> > > +    }
> > > +    xc_interface_close(vtpmdev->xen_xcs);
> > > +    return 0;
> > > +}
> > > +
> > > +static void vtpm_alloc(struct XenDevice *xendev)
> > > +{
> > > +    struct XenVtpmDev *vtpmdev = container_of(xendev, struct
> > XenVtpmDev,
> > > +                                              xendev);
> > > +
> > > +    vtpm_aio_ctx = aio_context_new(NULL);
> > > +    if (vtpm_aio_ctx == NULL) {
> > > +        return;
> > > +    }
> > > +    vtpmdev->sr_bh = aio_bh_new(vtpm_aio_ctx, sr_bh_handler,
> > vtpmdev);
> > > +    qemu_bh_schedule(vtpmdev->sr_bh);
> > > +    vtpmdev->xen_xcs = xen_xc_gntshr_open(0, 0);
> > > +}
> > > +
> > > +static void vtpm_event(struct XenDevice *xendev)
> > > +{
> > > +    struct XenVtpmDev *vtpmdev = container_of(xendev, struct
> > XenVtpmDev,
> > > +                                              xendev);
> > > +
> > > +    qemu_bh_schedule(vtpmdev->sr_bh);
> > > +}
> > > +
> > > +struct XenDevOps xen_vtpmdev_ops = {
> > > +    .size             = sizeof(struct XenVtpmDev),
> > > +    .flags            = DEVOPS_FLAG_IGNORE_STATE |
> > > +                        DEVOPS_FLAG_STUBDOM_BE,
> > > +    .event            = vtpm_event,
> > > +    .free             = vtpm_free,
> > > +    .alloc            = vtpm_alloc,
> > > +    .initialise       = vtpm_initialise,
> > > +    .backend_changed  = vtpm_backend_changed,
> > > +    .recv             = vtpm_recv,
> > > +    .send             = vtpm_send,
> > > +};
> > 
> > Is this the frontend, like the subject line would seem to imply?
> > If so, XenDevOps are made for backends, while this is a frontend. In
> > fact this is the first PV frontend in QEMU. We need to introduce
> > something generic and similar to struct XenDevOps and xen_backend.c but
> > for frontends.
> > 
> > 
> > > diff --git a/include/hw/xen/xen_backend.h
> > b/include/hw/xen/xen_backend.h
> > > index 3b4125e..45fd6d3 100644
> > > --- a/include/hw/xen/xen_backend.h
> > > +++ b/include/hw/xen/xen_backend.h
> > > @@ -15,6 +15,8 @@ struct XenDevice;
> > >  #define DEVOPS_FLAG_NEED_GNTDEV   1
> > >  /* don't expect frontend doing correct state transitions (aka console
> > quirk) */
> > >  #define DEVOPS_FLAG_IGNORE_STATE  2
> > > +/*dev backend is stubdom*/
> > > +#define DEVOPS_FLAG_STUBDOM_BE    4
> > >
> > >  struct XenDevOps {
> > >      size_t    size;
> > > @@ -26,6 +28,8 @@ struct XenDevOps {
> > >      void      (*event)(struct XenDevice *xendev);
> > >      void      (*disconnect)(struct XenDevice *xendev);
> > >      int       (*free)(struct XenDevice *xendev);
> > > +    int       (*send)(struct XenDevice *xendev, uint8_t* buf, size_t
> > count);
> > > +    int       (*recv)(struct XenDevice *xendev, uint8_t* buf, size_t
> > *count);
> > >      void      (*backend_changed)(struct XenDevice *xendev, const
> > char *node);
> > >      void      (*frontend_changed)(struct XenDevice *xendev, const
> > char *node);
> > >  };
> > > @@ -91,12 +95,19 @@ int xen_be_send_notify(struct XenDevice
> > *xendev);
> > >  void xen_be_printf(struct XenDevice *xendev, int msg_level, const char
> > *fmt, ...)
> > >      GCC_FMT_ATTR(3, 4);
> > >
> > > +/*Xen stubdom vtpm*/
> > > +int xen_vtpm_register(struct XenDevOps *ops);
> > > +int xen_be_alloc_unbound(struct XenDevice *xendev, int dom, int
> > remote_dom);
> > > +int xen_vtpm_send(unsigned char *buf, size_t count);
> > > +int xen_vtpm_recv(unsigned char *buf, size_t *count);
> > > +
> > >  /* actual backend drivers */
> > >  extern struct XenDevOps xen_console_ops;      /* xen_console.c
> > */
> > >  extern struct XenDevOps xen_kbdmouse_ops;     /* xen_framebuffer.c
> > */
> > >  extern struct XenDevOps xen_framebuffer_ops;  /* xen_framebuffer.c */
> > >  extern struct XenDevOps xen_blkdev_ops;       /* xen_disk.c
> > */
> > >  extern struct XenDevOps xen_netdev_ops;       /* xen_nic.c
> > */
> > > +extern struct XenDevOps xen_vtpmdev_ops;      /*
> > xen_stubdom_vtpm.c*/
> > >
> > >  void xen_init_display(int domid);
> > >
> > > diff --git a/include/hw/xen/xen_common.h
> > b/include/hw/xen/xen_common.h
> > > index 95612a4..fb43084 100644
> > > --- a/include/hw/xen/xen_common.h
> > > +++ b/include/hw/xen/xen_common.h
> > > @@ -130,6 +130,12 @@ static inline XenXC xen_xc_interface_open(void
> > *logger, void *dombuild_logger,
> > >      return xc_interface_open(logger, dombuild_logger, open_flags);
> > >  }
> > >
> > > +static inline xc_gntshr *xen_xc_gntshr_open(void *logger,
> > > +                                           unsigned int open_flags)
> > > +{
> > > +    return xc_gntshr_open(logger, open_flags);
> > > +}
> > > +
> > >  /* FIXME There is now way to have the xen fd */
> > >  static inline int xc_fd(xc_interface *xen_xc)
> > >  {
> > > diff --git a/xen-hvm.c b/xen-hvm.c
> > > index 21f1cbb..c99ace8 100644
> > > --- a/xen-hvm.c
> > > +++ b/xen-hvm.c
> > > @@ -1067,6 +1067,11 @@ int xen_hvm_init(ram_addr_t
> > *below_4g_mem_size, ram_addr_t *above_4g_mem_size,
> > >      int i, rc;
> > >      unsigned long ioreq_pfn;
> > >      unsigned long bufioreq_evtchn;
> > > +
> > > +#ifdef CONFIG_TPM_XENSTUBDOMS
> > > +    unsigned long stubdom_vtpm = 0;
> > > +#endif
> > > +
> > >      XenIOState *state;
> > >
> > >      state = g_malloc0(sizeof (XenIOState));
> > > @@ -1169,6 +1174,14 @@ int xen_hvm_init(ram_addr_t
> > *below_4g_mem_size, ram_addr_t *above_4g_mem_size,
> > >          fprintf(stderr, "%s: xen backend core setup failed\n",
> > __FUNCTION__);
> > >          return -1;
> > >      }
> > > +
> > > +#ifdef CONFIG_TPM_XENSTUBDOMS
> > > +    xc_get_hvm_param(xen_xc, xen_domid,
> > HVM_PARAM_STUBDOM_VTPM, &stubdom_vtpm);
> > > +    if (stubdom_vtpm) {
> > > +        xen_vtpm_register(&xen_vtpmdev_ops);
> > > +    }
> > > +#endif
> > 
> > Given that vtpm is just a PV frontend, can't you just detect whether is
> > present on xenstore and initialize it based on that? Like all the
> > backend below?
> 
> Also I will explain in my next email. 
> 
> 
> > 
> > 
> > >      xen_be_register("console", &xen_console_ops);
> > >      xen_be_register("vkbd", &xen_kbdmouse_ops);
> > >      xen_be_register("qdisk", &xen_blkdev_ops);
> > > --
> > > 1.8.3.2
> > >
> 

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