[Qemu-devel] [PATCH v6 3/6] Qemu-Xen-vTPM: Xen frontend driver infrastructure

[Quan Xu]

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,
         [...]
    3 = ""
     [...]
     device = "" (frontend device, the backend is running in QEMU/.etc)
      vkbd = ""
       [...]
      vif = ""
       [...]

 ..

(QEMU) xen_vtpmdev_ops is initialized with the following process:
  xen_hvm_init()
    [...]
    -->xen_fe_register("vtpm", ...)
      -->xenstore_fe_scan()
        -->xen_fe_try_init(ops)
          --> XenDevOps.init()
        -->xen_fe_get_xendev()
          --> XenDevOps.alloc()
        -->xen_fe_check()
          -->xen_fe_try_initialise()
            --> XenDevOps.initialise()
          -->xen_fe_try_connected()
            --> XenDevOps.connected()
        -->xs_watch()
    [...]

Signed-off-by: Quan Xu <address@hidden>

--Changes in v6:
 -Replace buf_size with PAGE_SIZE and use length rather than
  shr->length.
---
 hw/tpm/Makefile.objs         |   1 +
 hw/tpm/xen_vtpm_frontend.c   | 315 +++++++++++++++++++++++++++++++++++++++++++
 hw/xen/xen_frontend.c        |  20 +++
 include/hw/xen/xen_backend.h |   5 +
 include/hw/xen/xen_common.h  |   6 +
 xen-hvm.c                    |   5 +
 6 files changed, 352 insertions(+)
 create mode 100644 hw/tpm/xen_vtpm_frontend.c

diff --git a/hw/tpm/Makefile.objs b/hw/tpm/Makefile.objs
index 99f5983..57919fa 100644
--- a/hw/tpm/Makefile.objs
+++ b/hw/tpm/Makefile.objs
@@ -1,2 +1,3 @@
 common-obj-$(CONFIG_TPM_TIS) += tpm_tis.o
 common-obj-$(CONFIG_TPM_PASSTHROUGH) += tpm_passthrough.o
+common-obj-$(CONFIG_TPM_XENSTUBDOMS) += xen_vtpm_frontend.o
diff --git a/hw/tpm/xen_vtpm_frontend.c b/hw/tpm/xen_vtpm_frontend.c
new file mode 100644
index 0000000..d6e7cc6
--- /dev/null
+++ b/hw/tpm/xen_vtpm_frontend.c
@@ -0,0 +1,315 @@
+/*
+ * Connect to Xen vTPM stubdom domain
+ *
+ *  Copyright (c) 2015 Intel Corporation
+ *  Authors:
+ *    Quan Xu <address@hidden>
+ *
+ * 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"
+
+#ifndef XS_STUBDOM_VTPM_ENABLE
+#define XS_STUBDOM_VTPM_ENABLE    "1"
+#endif
+
+#ifndef PAGE_SIZE
+#define PAGE_SIZE      4096
+#endif
+
+enum tpmif_state {
+    /* No contents, vTPM idle, cancel complete */
+    TPMIF_STATE_IDLE,
+    /* Request ready or vTPM working */
+    TPMIF_STATE_SUBMIT,
+    /* Response ready or vTPM idle */
+    TPMIF_STATE_FINISH,
+    /* Cancel requested or vTPM working */
+    TPMIF_STATE_CANCEL,
+};
+
+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 {
+    /* Request and response length in bytes */
+    uint32_t length;
+    /* Enum tpmif_state */
+    uint8_t  state;
+    /* For the current request */
+    uint8_t  locality;
+    /* Should be zero */
+    uint8_t  pad;
+    /* Extra pages for long packets; may be zero */
+    uint8_t  nr_extra_pages;
+    /*
+     * Grant IDs, the length is actually nr_extra_pages.
+     * beyond the extra_pages entries is the actual request
+     * and response.
+     */
+    uint32_t extra_pages[0];
+};
+
+struct xen_vtpm_dev {
+    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 xen_vtpm_dev *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 bool vtpm_aio_wait(AioContext *ctx)
+{
+    return aio_poll(ctx, true);
+}
+
+static void sr_bh_handler(void *opaque)
+{
+}
+
+int vtpm_recv(struct XenDevice *xendev, uint8_t* buf, size_t *count)
+{
+    struct xen_vtpm_dev *vtpmdev = container_of(xendev, struct xen_vtpm_dev,
+                                                xendev);
+    struct tpmif_shared_page *shr = vtpmdev->shr;
+    unsigned int offset;
+    size_t length = shr->length;
+
+    if (shr->state == TPMIF_STATE_IDLE) {
+        return -ECANCELED;
+    }
+
+    offset = sizeof(*shr) + sizeof(shr->extra_pages[0])*shr->nr_extra_pages;
+    if (offset > PAGE_SIZE) {
+        return -EIO;
+    }
+
+    if (offset + length > PAGE_SIZE) {
+        length = PAGE_SIZE - offset;
+    }
+
+    memcpy(buf, offset + (uint8_t *)shr, length);
+    *count = length;
+
+    return 0;
+}
+
+int vtpm_send(struct XenDevice *xendev, uint8_t* buf, size_t count)
+{
+    struct xen_vtpm_dev *vtpmdev = container_of(xendev, struct xen_vtpm_dev,
+                                                xendev);
+    struct tpmif_shared_page *shr = vtpmdev->shr;
+    unsigned int offset = sizeof(*shr) +
+                          sizeof(shr->extra_pages[0])*shr->nr_extra_pages;
+
+    if (offset > PAGE_SIZE) {
+        return -EIO;
+    }
+
+    if (offset + count > PAGE_SIZE) {
+        return -ECANCELED;
+    }
+
+    while (vtpm_status(vtpmdev) != VTPM_STATUS_IDLE) {
+        vtpm_aio_wait(vtpm_aio_ctx);
+    }
+
+    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(vtpm_aio_ctx);
+    }
+
+    return count;
+}
+
+static int vtpm_initialise(struct XenDevice *xendev)
+{
+    struct xen_vtpm_dev *vtpmdev = container_of(xendev, struct xen_vtpm_dev,
+                                                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 shared 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_fe_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;
+        }
+    }
+
+    return 0;
+
+abort_transaction:
+    xc_gntshr_munmap(vtpmdev->xen_xcs, vtpmdev->shr, 1);
+    xs_transaction_end(xenstore, xbt, 1);
+    return -1;
+}
+
+static int vtpm_free(struct XenDevice *xendev)
+{
+    struct xen_vtpm_dev *vtpmdev = container_of(xendev, struct xen_vtpm_dev,
+                                                xendev);
+
+    aio_poll(vtpm_aio_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 int vtpm_init(struct XenDevice *xendev)
+{
+    char path[XEN_BUFSIZE];
+    char *value;
+    unsigned int stubdom_vtpm = 0;
+
+    snprintf(path, sizeof(path), "/local/domain/%d/platform/acpi_stubdom_vtpm",
+             xen_domid);
+    value = xs_read(xenstore, 0, path, &stubdom_vtpm);
+    if (stubdom_vtpm <= 0 || strcmp(value, XS_STUBDOM_VTPM_ENABLE)) {
+        free(value);
+        return -1;
+    }
+    free(value);
+    return 0;
+}
+
+static void vtpm_alloc(struct XenDevice *xendev)
+{
+    struct xen_vtpm_dev *vtpmdev = container_of(xendev, struct xen_vtpm_dev,
+                                                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 xen_vtpm_dev *vtpmdev = container_of(xendev, struct xen_vtpm_dev,
+                                                xendev);
+
+    qemu_bh_schedule(vtpmdev->sr_bh);
+}
+
+struct XenDevOps xen_vtpmdev_ops = {
+    .size             = sizeof(struct xen_vtpm_dev),
+    .flags            = DEVOPS_FLAG_IGNORE_STATE |
+                        DEVOPS_FLAG_FE,
+    .event            = vtpm_event,
+    .free             = vtpm_free,
+    .init             = vtpm_init,
+    .alloc            = vtpm_alloc,
+    .initialise       = vtpm_initialise,
+    .backend_changed  = vtpm_backend_changed,
+};
diff --git a/hw/xen/xen_frontend.c b/hw/xen/xen_frontend.c
index 55af45a..1ca7342 100644
--- a/hw/xen/xen_frontend.c
+++ b/hw/xen/xen_frontend.c
@@ -60,6 +60,26 @@ static void xen_fe_evtchn_event(void *opaque)
 
 /* ------------------------------------------------------------- */
 
+void vtpm_backend_changed(struct XenDevice *xendev, const char *node)
+{
+    int be_state;
+
+    if (strcmp(node, "state") == 0) {
+        xenstore_read_be_int(xendev, node, &be_state);
+        switch (be_state) {
+        case XenbusStateConnected:
+            /* TODO */
+            break;
+        case XenbusStateClosing:
+        case XenbusStateClosed:
+            xenbus_switch_state(xendev, XenbusStateClosing);
+            break;
+        default:
+            break;
+        }
+    }
+}
+
 int xen_fe_alloc_unbound(struct XenDevice *xendev, int dom, int remote_dom)
 {
     xendev->local_port = xc_evtchn_bind_unbound_port(xendev->evtchndev,
diff --git a/include/hw/xen/xen_backend.h b/include/hw/xen/xen_backend.h
index bb0b303..b959413 100644
--- a/include/hw/xen/xen_backend.h
+++ b/include/hw/xen/xen_backend.h
@@ -110,6 +110,11 @@ int xen_fe_register(const char *type, struct XenDevOps 
*ops);
 int xen_fe_alloc_unbound(struct XenDevice *xendev, int dom, int remote_dom);
 int xenbus_switch_state(struct XenDevice *xendev, enum xenbus_state xbus);
 
+/* Xen vtpm */
+int vtpm_send(struct XenDevice *xendev, uint8_t* buf, size_t count);
+int vtpm_recv(struct XenDevice *xendev, uint8_t* buf, size_t *count);
+void vtpm_backend_changed(struct XenDevice *xendev, const char *node);
+
 /* actual backend drivers */
 extern struct XenDevOps xen_console_ops;      /* xen_console.c     */
 extern struct XenDevOps xen_kbdmouse_ops;     /* xen_framebuffer.c */
diff --git a/include/hw/xen/xen_common.h b/include/hw/xen/xen_common.h
index 38f29fb..7268d0c 100644
--- a/include/hw/xen/xen_common.h
+++ b/include/hw/xen/xen_common.h
@@ -132,6 +132,12 @@ 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 315864c..b2403dc 100644
--- a/xen-hvm.c
+++ b/xen-hvm.c
@@ -1308,6 +1308,11 @@ 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
+    xen_fe_register("vtpm", &xen_vtpmdev_ops);
+#endif
+
     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