[Xen-devel] [PATCH 01/13] mini-os/tpm{back, front}: Change shared page ABI

[Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>]

This changes the vTPM shared page ABI from a copy of the Xen network
interface to a single-page interface that better reflects the expected
behavior of a TPM: only a single request packet can be sent at any given
time, and every packet sent generates a single response packet. This
protocol change should also increase efficiency as it avoids mapping and
unmapping grants when possible. The vtpm xenbus device has been renamed
to "vtpm2" to avoid conflicts with existing (xen-patched) kernels
supporting the old interface.

While the contents of the shared page have been defined to allow packets
larger than a single page (actually 4088 bytes) by allowing the client
to add extra grant references, the mapping of these extra references has
not been implemented; a feature node in xenstore may be used in the
future to indicate full support for the multi-page protocol. Most uses
of the TPM should not require this feature.

Signed-off-by: Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>

---

Changes from v3.0: the change to "vtpm2" in libxl was incomplete,
causing the vtpm-attach command to fail.
---
 extras/mini-os/include/tpmback.h     |   1 +
 extras/mini-os/include/tpmfront.h    |   7 +-
 extras/mini-os/tpmback.c             | 135 +++++++++++++----------------------
 extras/mini-os/tpmfront.c            | 119 ++++++++++++------------------
 tools/libxl/libxl.c                  |  12 ++--
 tools/libxl/libxl_types_internal.idl |   2 +-
 xen/include/public/io/tpmif.h        |  45 +++---------
 7 files changed, 117 insertions(+), 204 deletions(-)

diff --git a/extras/mini-os/include/tpmback.h b/extras/mini-os/include/tpmback.h
index ff86732..ec9eda4 100644
--- a/extras/mini-os/include/tpmback.h
+++ b/extras/mini-os/include/tpmback.h
@@ -43,6 +43,7 @@
 
 struct tpmcmd {
    domid_t domid;              /* Domid of the frontend */
+   uint8_t locality;    /* Locality requested by the frontend */
    unsigned int handle;        /* Handle of the frontend */
    unsigned char uuid[16];                     /* uuid of the tpm interface */
 
diff --git a/extras/mini-os/include/tpmfront.h 
b/extras/mini-os/include/tpmfront.h
index fd2cb17..a0c7c4d 100644
--- a/extras/mini-os/include/tpmfront.h
+++ b/extras/mini-os/include/tpmfront.h
@@ -37,9 +37,7 @@ struct tpmfront_dev {
    grant_ref_t ring_ref;
    evtchn_port_t evtchn;
 
-   tpmif_tx_interface_t* tx;
-
-   void** pages;
+   vtpm_shared_page_t *page;
 
    domid_t bedomid;
    char* nodename;
@@ -77,6 +75,9 @@ void shutdown_tpmfront(struct tpmfront_dev* dev);
  * */
 int tpmfront_cmd(struct tpmfront_dev* dev, uint8_t* req, size_t reqlen, 
uint8_t** resp, size_t* resplen);
 
+/* Set the locality used for communicating with a vTPM */
+int tpmfront_set_locality(struct tpmfront_dev* dev, int locality);
+
 #ifdef HAVE_LIBC
 #include <sys/stat.h>
 /* POSIX IO functions:
diff --git a/extras/mini-os/tpmback.c b/extras/mini-os/tpmback.c
index 658fed1..50f8a5d 100644
--- a/extras/mini-os/tpmback.c
+++ b/extras/mini-os/tpmback.c
@@ -86,10 +86,7 @@ struct tpmif {
    evtchn_port_t evtchn;
 
    /* Shared page */
-   tpmif_tx_interface_t* tx;
-
-   /* pointer to TPMIF_RX_RING_SIZE pages */
-   void** pages;
+   vtpm_shared_page_t *page;
 
    enum xenbus_state state;
    enum { DISCONNECTED, DISCONNECTING, CONNECTED } status;
@@ -312,7 +309,6 @@ int insert_tpmif(tpmif_t* tpmif)
       remove_tpmif(tpmif);
       goto error_post_irq;
    }
-
    return 0;
 error:
    local_irq_restore(flags);
@@ -336,7 +332,7 @@ int tpmif_change_state(tpmif_t* tpmif, enum xenbus_state 
state)
    if (tpmif->state == state)
       return 0;
 
-   snprintf(path, 512, "backend/vtpm/%u/%u/state", (unsigned int) 
tpmif->domid, tpmif->handle);
+   snprintf(path, 512, "backend/vtpm2/%u/%u/state", (unsigned int) 
tpmif->domid, tpmif->handle);
 
    if((err = xenbus_read(XBT_NIL, path, &value))) {
       TPMBACK_ERR("Unable to read backend state %s, error was %s\n", path, 
err);
@@ -362,7 +358,7 @@ int tpmif_change_state(tpmif_t* tpmif, enum xenbus_state 
state)
    }
 
    /*update xenstore*/
-   snprintf(path, 512, "backend/vtpm/%u/%u", (unsigned int) tpmif->domid, 
tpmif->handle);
+   snprintf(path, 512, "backend/vtpm2/%u/%u", (unsigned int) tpmif->domid, 
tpmif->handle);
    if((err = xenbus_printf(XBT_NIL, path, "state", "%u", state))) {
       TPMBACK_ERR("Error writing to xenstore %s, error was %s new state=%d\n", 
path, err, state);
       free(err);
@@ -386,8 +382,7 @@ inline tpmif_t* __init_tpmif(domid_t domid, unsigned int 
handle)
    tpmif->fe_state_path = NULL;
    tpmif->state = XenbusStateInitialising;
    tpmif->status = DISCONNECTED;
-   tpmif->tx = NULL;
-   tpmif->pages = NULL;
+   tpmif->page = NULL;
    tpmif->flags = 0;
    memset(tpmif->uuid, 0, sizeof(tpmif->uuid));
    return tpmif;
@@ -395,9 +390,6 @@ inline tpmif_t* __init_tpmif(domid_t domid, unsigned int 
handle)
 
 void __free_tpmif(tpmif_t* tpmif)
 {
-   if(tpmif->pages) {
-      free(tpmif->pages);
-   }
    if(tpmif->fe_path) {
       free(tpmif->fe_path);
    }
@@ -424,23 +416,17 @@ tpmif_t* new_tpmif(domid_t domid, unsigned int handle)
    tpmif = __init_tpmif(domid, handle);
 
    /* Get the uuid from xenstore */
-   snprintf(path, 512, "backend/vtpm/%u/%u/uuid", (unsigned int) domid, 
handle);
+   snprintf(path, 512, "backend/vtpm2/%u/%u/uuid", (unsigned int) domid, 
handle);
    if((!xenbus_read_uuid(path, tpmif->uuid))) {
       TPMBACK_ERR("Error reading %s\n", path);
       goto error;
    }
 
-   /* allocate pages to be used for shared mapping */
-   if((tpmif->pages = malloc(sizeof(void*) * TPMIF_TX_RING_SIZE)) == NULL) {
-      goto error;
-   }
-   memset(tpmif->pages, 0, sizeof(void*) * TPMIF_TX_RING_SIZE);
-
    if(tpmif_change_state(tpmif, XenbusStateInitWait)) {
       goto error;
    }
 
-   snprintf(path, 512, "backend/vtpm/%u/%u/frontend", (unsigned int) domid, 
handle);
+   snprintf(path, 512, "backend/vtpm2/%u/%u/frontend", (unsigned int) domid, 
handle);
    if((err = xenbus_read(XBT_NIL, path, &tpmif->fe_path))) {
       TPMBACK_ERR("Error creating new tpm instance xenbus_read(%s), Error = 
%s", path, err);
       free(err);
@@ -486,7 +472,7 @@ void free_tpmif(tpmif_t* tpmif)
       tpmif->status = DISCONNECTING;
       mask_evtchn(tpmif->evtchn);
 
-      if(gntmap_munmap(&gtpmdev.map, (unsigned long)tpmif->tx, 1)) {
+      if(gntmap_munmap(&gtpmdev.map, (unsigned long)tpmif->page, 1)) {
         TPMBACK_ERR("%u/%u Error occured while trying to unmap shared page\n", 
(unsigned int) tpmif->domid, tpmif->handle);
       }
 
@@ -508,7 +494,7 @@ void free_tpmif(tpmif_t* tpmif)
    schedule();
 
    /* Remove the old xenbus entries */
-   snprintf(path, 512, "backend/vtpm/%u/%u", (unsigned int) tpmif->domid, 
tpmif->handle);
+   snprintf(path, 512, "backend/vtpm2/%u/%u", (unsigned int) tpmif->domid, 
tpmif->handle);
    if((err = xenbus_rm(XBT_NIL, path))) {
       TPMBACK_ERR("Error cleaning up xenbus entries path=%s error=%s\n", path, 
err);
       free(err);
@@ -529,9 +515,10 @@ void free_tpmif(tpmif_t* tpmif)
 void tpmback_handler(evtchn_port_t port, struct pt_regs *regs, void *data)
 {
    tpmif_t* tpmif = (tpmif_t*) data;
-   tpmif_tx_request_t* tx = &tpmif->tx->ring[0].req;
-   /* Throw away 0 size events, these can trigger from event channel unmasking 
*/
-   if(tx->size == 0)
+   vtpm_shared_page_t* pg = tpmif->page;
+
+   /* Only pay attention if the request is ready */
+   if (pg->state == 0)
       return;
 
    TPMBACK_DEBUG("EVENT CHANNEL FIRE %u/%u\n", (unsigned int) tpmif->domid, 
tpmif->handle);
@@ -585,11 +572,10 @@ int connect_fe(tpmif_t* tpmif)
    free(value);
 
    domid = tpmif->domid;
-   if((tpmif->tx = gntmap_map_grant_refs(&gtpmdev.map, 1, &domid, 0, &ringref, 
PROT_READ | PROT_WRITE)) == NULL) {
+   if((tpmif->page = gntmap_map_grant_refs(&gtpmdev.map, 1, &domid, 0, 
&ringref, PROT_READ | PROT_WRITE)) == NULL) {
       TPMBACK_ERR("Failed to map grant reference %u/%u\n", (unsigned int) 
tpmif->domid, tpmif->handle);
       return -1;
    }
-   memset(tpmif->tx, 0, PAGE_SIZE);
 
    /*Bind the event channel */
    if((evtchn_bind_interdomain(tpmif->domid, evtchn, tpmback_handler, tpmif, 
&tpmif->evtchn)))
@@ -600,7 +586,7 @@ int connect_fe(tpmif_t* tpmif)
    unmask_evtchn(tpmif->evtchn);
 
    /* Write the ready flag and change status to connected */
-   snprintf(path, 512, "backend/vtpm/%u/%u", (unsigned int) tpmif->domid, 
tpmif->handle);
+   snprintf(path, 512, "backend/vtpm2/%u/%u", (unsigned int) tpmif->domid, 
tpmif->handle);
    if((err = xenbus_printf(XBT_NIL, path, "ready", "%u", 1))) {
       TPMBACK_ERR("%u/%u Unable to write ready flag on connect_fe()\n", 
(unsigned int) tpmif->domid, tpmif->handle);
       free(err);
@@ -618,7 +604,7 @@ error_post_evtchn:
    mask_evtchn(tpmif->evtchn);
    unbind_evtchn(tpmif->evtchn);
 error_post_map:
-   gntmap_munmap(&gtpmdev.map, (unsigned long)tpmif->tx, 1);
+   gntmap_munmap(&gtpmdev.map, (unsigned long)tpmif->page, 1);
    return -1;
 }
 
@@ -670,8 +656,8 @@ static int parse_eventstr(const char* evstr, domid_t* 
domid, unsigned int* handl
    char* value;
    unsigned int udomid = 0;
    tpmif_t* tpmif;
-   /* First check for new frontends, this occurs when 
/backend/vtpm/<domid>/<handle> gets created. Note we what the sscanf to fail on 
the last %s */
-   if (sscanf(evstr, "backend/vtpm/%u/%u/%40s", &udomid, handle, cmd) == 2) {
+   /* First check for new frontends, this occurs when 
/backend/vtpm2/<domid>/<handle> gets created. Note we what the sscanf to fail 
on the last %s */
+   if (sscanf(evstr, "backend/vtpm2/%u/%u/%40s", &udomid, handle, cmd) == 2) {
       *domid = udomid;
       /* Make sure the entry exists, if this event triggers because the entry 
dissapeared then ignore it */
       if((err = xenbus_read(XBT_NIL, evstr, &value))) {
@@ -685,7 +671,7 @@ static int parse_eventstr(const char* evstr, domid_t* 
domid, unsigned int* handl
         return EV_NONE;
       }
       return EV_NEWFE;
-   } else if((ret = sscanf(evstr, "/local/domain/%u/device/vtpm/%u/%40s", 
&udomid, handle, cmd)) == 3) {
+   } else if((ret = sscanf(evstr, "/local/domain/%u/device/vtpm2/%u/%40s", 
&udomid, handle, cmd)) == 3) {
       *domid = udomid;
       if (!strcmp(cmd, "state"))
         return EV_STCHNG;
@@ -784,7 +770,7 @@ void tpmback_set_resume_callback(void (*cb)(domid_t, 
unsigned int))
 
 static void event_listener(void)
 {
-   const char* bepath = "backend/vtpm";
+   const char* bepath = "backend/vtpm2";
    char **path;
    char* err;
 
@@ -874,6 +860,7 @@ void shutdown_tpmback(void)
 inline void init_tpmcmd(tpmcmd_t* tpmcmd, domid_t domid, unsigned int handle, 
unsigned char uuid[16])
 {
    tpmcmd->domid = domid;
+   tpmcmd->locality = -1;
    tpmcmd->handle = handle;
    memcpy(tpmcmd->uuid, uuid, sizeof(tpmcmd->uuid));
    tpmcmd->req = NULL;
@@ -884,12 +871,12 @@ inline void init_tpmcmd(tpmcmd_t* tpmcmd, domid_t domid, 
unsigned int handle, un
 
 tpmcmd_t* get_request(tpmif_t* tpmif) {
    tpmcmd_t* cmd;
-   tpmif_tx_request_t* tx;
-   int offset;
-   int tocopy;
-   int i;
-   uint32_t domid;
+   vtpm_shared_page_t* shr;
+   unsigned int offset;
    int flags;
+#ifdef TPMBACK_PRINT_DEBUG
+   int i;
+#endif
 
    local_irq_save(flags);
 
@@ -899,35 +886,22 @@ tpmcmd_t* get_request(tpmif_t* tpmif) {
    }
    init_tpmcmd(cmd, tpmif->domid, tpmif->handle, tpmif->uuid);
 
-   tx = &tpmif->tx->ring[0].req;
-   cmd->req_len = tx->size;
+   shr = tpmif->page;
+   cmd->req_len = shr->length;
+   cmd->locality = shr->locality;
+   offset = sizeof(*shr) + 4*shr->nr_extra_pages;
+   if (offset > PAGE_SIZE || offset + cmd->req_len > PAGE_SIZE) {
+      TPMBACK_ERR("%u/%u Command size too long for shared page!\n", (unsigned 
int) tpmif->domid, tpmif->handle);
+      goto error;
+   }
    /* Allocate the buffer */
    if(cmd->req_len) {
       if((cmd->req = malloc(cmd->req_len)) == NULL) {
         goto error;
       }
    }
-   /* Copy the bits from the shared pages */
-   offset = 0;
-   for(i = 0; i < TPMIF_TX_RING_SIZE && offset < cmd->req_len; ++i) {
-      tx = &tpmif->tx->ring[i].req;
-
-      /* Map the page with the data */
-      domid = (uint32_t)tpmif->domid;
-      if((tpmif->pages[i] = gntmap_map_grant_refs(&gtpmdev.map, 1, &domid, 0, 
&tx->ref, PROT_READ)) == NULL) {
-        TPMBACK_ERR("%u/%u Unable to map shared page during read!\n", 
(unsigned int) tpmif->domid, tpmif->handle);
-        goto error;
-      }
-
-      /* do the copy now */
-      tocopy = min(cmd->req_len - offset, PAGE_SIZE);
-      memcpy(&cmd->req[offset], tpmif->pages[i], tocopy);
-      offset += tocopy;
-
-      /* release the page */
-      gntmap_munmap(&gtpmdev.map, (unsigned long)tpmif->pages[i], 1);
-
-   }
+   /* Copy the bits from the shared page(s) */
+   memcpy(cmd->req, offset + (uint8_t*)shr, cmd->req_len);
 
 #ifdef TPMBACK_PRINT_DEBUG
    TPMBACK_DEBUG("Received Tpm Command from %u/%u of size %u", (unsigned int) 
tpmif->domid, tpmif->handle, cmd->req_len);
@@ -958,38 +932,24 @@ error:
 
 void send_response(tpmcmd_t* cmd, tpmif_t* tpmif)
 {
-   tpmif_tx_request_t* tx;
-   int offset;
-   int i;
-   uint32_t domid;
-   int tocopy;
+   vtpm_shared_page_t* shr;
+   unsigned int offset;
    int flags;
+#ifdef TPMBACK_PRINT_DEBUG
+int i;
+#endif
 
    local_irq_save(flags);
 
-   tx = &tpmif->tx->ring[0].req;
-   tx->size = cmd->resp_len;
-
-   offset = 0;
-   for(i = 0; i < TPMIF_TX_RING_SIZE && offset < cmd->resp_len; ++i) {
-      tx = &tpmif->tx->ring[i].req;
-
-      /* Map the page with the data */
-      domid = (uint32_t)tpmif->domid;
-      if((tpmif->pages[i] = gntmap_map_grant_refs(&gtpmdev.map, 1, &domid, 0, 
&tx->ref, PROT_WRITE)) == NULL) {
-        TPMBACK_ERR("%u/%u Unable to map shared page during write!\n", 
(unsigned int) tpmif->domid, tpmif->handle);
-        goto error;
-      }
-
-      /* do the copy now */
-      tocopy = min(cmd->resp_len - offset, PAGE_SIZE);
-      memcpy(tpmif->pages[i], &cmd->resp[offset], tocopy);
-      offset += tocopy;
-
-      /* release the page */
-      gntmap_munmap(&gtpmdev.map, (unsigned long)tpmif->pages[i], 1);
+   shr = tpmif->page;
+   shr->length = cmd->resp_len;
 
+   offset = sizeof(*shr) + 4*shr->nr_extra_pages;
+   if (offset > PAGE_SIZE || offset + cmd->resp_len > PAGE_SIZE) {
+      TPMBACK_ERR("%u/%u Command size too long for shared page!\n", (unsigned 
int) tpmif->domid, tpmif->handle);
+      goto error;
    }
+   memcpy(offset + (uint8_t*)shr, cmd->resp, cmd->resp_len);
 
 #ifdef TPMBACK_PRINT_DEBUG
    TPMBACK_DEBUG("Sent response to %u/%u of size %u", (unsigned int) 
tpmif->domid, tpmif->handle, cmd->resp_len);
@@ -1003,6 +963,7 @@ void send_response(tpmcmd_t* cmd, tpmif_t* tpmif)
 #endif
    /* clear the ready flag and send the event channel notice to the frontend */
    tpmif_req_finished(tpmif);
+   shr->state = 0;
    notify_remote_via_evtchn(tpmif->evtchn);
 error:
    local_irq_restore(flags);
diff --git a/extras/mini-os/tpmfront.c b/extras/mini-os/tpmfront.c
index 0218d7f..ac9ba42 100644
--- a/extras/mini-os/tpmfront.c
+++ b/extras/mini-os/tpmfront.c
@@ -176,7 +176,7 @@ static int wait_for_backend_state_changed(struct 
tpmfront_dev* dev, XenbusState
         ret = wait_for_backend_closed(&events, path);
         break;
       default:
-        break;
+         TPMFRONT_ERR("Bad wait state %d, ignoring\n", state);
    }
 
    if((err = xenbus_unwatch_path_token(XBT_NIL, path, path))) {
@@ -190,13 +190,13 @@ static int tpmfront_connect(struct tpmfront_dev* dev)
 {
    char* err;
    /* Create shared page */
-   dev->tx = (tpmif_tx_interface_t*) alloc_page();
-   if(dev->tx == NULL) {
+   dev->page = (vtpm_shared_page_t*) alloc_page();
+   if(dev->page == NULL) {
       TPMFRONT_ERR("Unable to allocate page for shared memory\n");
       goto error;
    }
-   memset(dev->tx, 0, PAGE_SIZE);
-   dev->ring_ref = gnttab_grant_access(dev->bedomid, virt_to_mfn(dev->tx), 0);
+   memset(dev->page, 0, PAGE_SIZE);
+   dev->ring_ref = gnttab_grant_access(dev->bedomid, virt_to_mfn(dev->page), 
0);
    TPMFRONT_DEBUG("grant ref is %lu\n", (unsigned long) dev->ring_ref);
 
    /*Create event channel */
@@ -228,7 +228,7 @@ error_postevtchn:
       unbind_evtchn(dev->evtchn);
 error_postmap:
       gnttab_end_access(dev->ring_ref);
-      free_page(dev->tx);
+      free_page(dev->page);
 error:
    return -1;
 }
@@ -240,7 +240,6 @@ struct tpmfront_dev* init_tpmfront(const char* _nodename)
    char path[512];
    char* value, *err;
    unsigned long long ival;
-   int i;
 
    printk("============= Init TPM Front ================\n");
 
@@ -251,7 +250,7 @@ struct tpmfront_dev* init_tpmfront(const char* _nodename)
    dev->fd = -1;
 #endif
 
-   nodename = _nodename ? _nodename : "device/vtpm/0";
+   nodename = _nodename ? _nodename : "device/vtpm2/0";
    dev->nodename = strdup(nodename);
 
    init_waitqueue_head(&dev->waitq);
@@ -289,19 +288,6 @@ struct tpmfront_dev* init_tpmfront(const char* _nodename)
       goto error;
    }
 
-   /* Allocate pages that will contain the messages */
-   dev->pages = malloc(sizeof(void*) * TPMIF_TX_RING_SIZE);
-   if(dev->pages == NULL) {
-      goto error;
-   }
-   memset(dev->pages, 0, sizeof(void*) * TPMIF_TX_RING_SIZE);
-   for(i = 0; i < TPMIF_TX_RING_SIZE; ++i) {
-      dev->pages[i] = (void*)alloc_page();
-      if(dev->pages[i] == NULL) {
-        goto error;
-      }
-   }
-
    TPMFRONT_LOG("Initialization Completed successfully\n");
 
    return dev;
@@ -314,8 +300,6 @@ void shutdown_tpmfront(struct tpmfront_dev* dev)
 {
    char* err;
    char path[512];
-   int i;
-   tpmif_tx_request_t* tx;
    if(dev == NULL) {
       return;
    }
@@ -349,27 +333,12 @@ void shutdown_tpmfront(struct tpmfront_dev* dev)
       /* Wait for the backend to close and unmap shared pages, ignore any 
errors */
       wait_for_backend_state_changed(dev, XenbusStateClosed);
 
-      /* Cleanup any shared pages */
-      if(dev->pages) {
-        for(i = 0; i < TPMIF_TX_RING_SIZE; ++i) {
-           if(dev->pages[i]) {
-              tx = &dev->tx->ring[i].req;
-              if(tx->ref != 0) {
-                 gnttab_end_access(tx->ref);
-              }
-              free_page(dev->pages[i]);
-           }
-        }
-        free(dev->pages);
-      }
-
       /* Close event channel and unmap shared page */
       mask_evtchn(dev->evtchn);
       unbind_evtchn(dev->evtchn);
       gnttab_end_access(dev->ring_ref);
 
-      free_page(dev->tx);
-
+      free_page(dev->page);
    }
 
    /* Cleanup memory usage */
@@ -387,13 +356,17 @@ void shutdown_tpmfront(struct tpmfront_dev* dev)
 
 int tpmfront_send(struct tpmfront_dev* dev, const uint8_t* msg, size_t length)
 {
+   unsigned int offset;
+   vtpm_shared_page_t* shr = NULL;
+#ifdef TPMFRONT_PRINT_DEBUG
    int i;
-   tpmif_tx_request_t* tx = NULL;
+#endif
    /* Error Checking */
    if(dev == NULL || dev->state != XenbusStateConnected) {
       TPMFRONT_ERR("Tried to send message through disconnected frontend\n");
       return -1;
    }
+   shr = dev->page;
 
 #ifdef TPMFRONT_PRINT_DEBUG
    TPMFRONT_DEBUG("Sending Msg to backend size=%u", (unsigned int) length);
@@ -407,19 +380,16 @@ int tpmfront_send(struct tpmfront_dev* dev, const 
uint8_t* msg, size_t length)
 #endif
 
    /* Copy to shared pages now */
-   for(i = 0; length > 0 && i < TPMIF_TX_RING_SIZE; ++i) {
-      /* Share the page */
-      tx = &dev->tx->ring[i].req;
-      tx->unused = 0;
-      tx->addr = virt_to_mach(dev->pages[i]);
-      tx->ref = gnttab_grant_access(dev->bedomid, virt_to_mfn(dev->pages[i]), 
0);
-      /* Copy the bits to the page */
-      tx->size = length > PAGE_SIZE ? PAGE_SIZE : length;
-      memcpy(dev->pages[i], &msg[i * PAGE_SIZE], tx->size);
-
-      /* Update counters */
-      length -= tx->size;
+   offset = sizeof(*shr);
+   if (length + offset > PAGE_SIZE) {
+      TPMFRONT_ERR("Message too long for shared page\n");
+      return -1;
    }
+   memcpy(offset + (uint8_t*)shr, msg, length);
+   shr->length = length;
+   barrier();
+   shr->state = 1;
+
    dev->waiting = 1;
    dev->resplen = 0;
 #ifdef HAVE_LIBC
@@ -434,44 +404,41 @@ int tpmfront_send(struct tpmfront_dev* dev, const 
uint8_t* msg, size_t length)
 }
 int tpmfront_recv(struct tpmfront_dev* dev, uint8_t** msg, size_t *length)
 {
-   tpmif_tx_request_t* tx;
-   int i;
+   unsigned int offset;
+   vtpm_shared_page_t* shr = NULL;
+#ifdef TPMFRONT_PRINT_DEBUG
+int i;
+#endif
    if(dev == NULL || dev->state != XenbusStateConnected) {
       TPMFRONT_ERR("Tried to receive message from disconnected frontend\n");
       return -1;
    }
    /*Wait for the response */
    wait_event(dev->waitq, (!dev->waiting));
+   shr = dev->page;
+   if (shr->state != 0)
+      goto quit;
 
    /* Initialize */
    *msg = NULL;
-   *length = 0;
+   *length = shr->length;
+   offset = sizeof(*shr);
 
-   /* special case, just quit */
-   tx = &dev->tx->ring[0].req;
-   if(tx->size == 0 ) {
-       goto quit;
-   }
-   /* Get the total size */
-   tx = &dev->tx->ring[0].req;
-   for(i = 0; i < TPMIF_TX_RING_SIZE && tx->size > 0; ++i) {
-      tx = &dev->tx->ring[i].req;
-      *length += tx->size;
+   if (*length + offset > PAGE_SIZE) {
+      TPMFRONT_ERR("Reply too long for shared page\n");
+      return -1;
    }
+
    /* Alloc the buffer */
    if(dev->respbuf) {
       free(dev->respbuf);
    }
    *msg = dev->respbuf = malloc(*length);
    dev->resplen = *length;
+
    /* Copy the bits */
-   tx = &dev->tx->ring[0].req;
-   for(i = 0; i < TPMIF_TX_RING_SIZE && tx->size > 0; ++i) {
-      tx = &dev->tx->ring[i].req;
-      memcpy(&(*msg)[i * PAGE_SIZE], dev->pages[i], tx->size);
-      gnttab_end_access(tx->ref);
-      tx->ref = 0;
-   }
+   memcpy(*msg, offset + (uint8_t*)shr, *length);
+
 #ifdef TPMFRONT_PRINT_DEBUG
    TPMFRONT_DEBUG("Received response from backend size=%u", (unsigned int) 
*length);
    for(i = 0; i < *length; ++i) {
@@ -504,6 +471,14 @@ int tpmfront_cmd(struct tpmfront_dev* dev, uint8_t* req, 
size_t reqlen, uint8_t*
    return 0;
 }
 
+int tpmfront_set_locality(struct tpmfront_dev* dev, int locality)
+{
+   if (!dev || !dev->page)
+      return -1;
+   dev->page->locality = locality;
+   return 0;
+}
+
 #ifdef HAVE_LIBC
 #include <errno.h>
 int tpmfront_open(struct tpmfront_dev* dev)
diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index 73e0dc3..2de9c99 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -1745,10 +1745,10 @@ static int libxl__device_from_vtpm(libxl__gc *gc, 
uint32_t domid,
 {
    device->backend_devid   = vtpm->devid;
    device->backend_domid   = vtpm->backend_domid;
-   device->backend_kind    = LIBXL__DEVICE_KIND_VTPM;
+   device->backend_kind    = LIBXL__DEVICE_KIND_VTPM2;
    device->devid           = vtpm->devid;
    device->domid           = domid;
-   device->kind            = LIBXL__DEVICE_KIND_VTPM;
+   device->kind            = LIBXL__DEVICE_KIND_VTPM2;
 
    return 0;
 }
@@ -1770,7 +1770,7 @@ void libxl__device_vtpm_add(libxl__egc *egc, uint32_t 
domid,
     back = flexarray_make(gc, 16, 1);
 
     if (vtpm->devid == -1) {
-        if ((vtpm->devid = libxl__device_nextid(gc, domid, "vtpm") < 0)) {
+        if ((vtpm->devid = libxl__device_nextid(gc, domid, "vtpm2") < 0)) {
             rc = ERROR_FAIL;
             goto out;
         }
@@ -1827,7 +1827,7 @@ libxl_device_vtpm *libxl_device_vtpm_list(libxl_ctx *ctx, 
uint32_t domid, int *n
 
     *num = 0;
 
-    fe_path = libxl__sprintf(gc, "%s/device/vtpm", libxl__xs_get_dompath(gc, 
domid));
+    fe_path = libxl__sprintf(gc, "%s/device/vtpm2", libxl__xs_get_dompath(gc, 
domid));
     dir = libxl__xs_directory(gc, XBT_NULL, fe_path, &ndirs);
     if(dir) {
        vtpms = malloc(sizeof(*vtpms) * ndirs);
@@ -1842,7 +1842,7 @@ libxl_device_vtpm *libxl_device_vtpm_list(libxl_ctx *ctx, 
uint32_t domid, int *n
           vtpm->devid = atoi(*dir);
 
           tmp = libxl__xs_read(gc, XBT_NULL,
-                GCSPRINTF("%s/%s/backend_id",
+                GCSPRINTF("%s/%s/backend-id",
                    fe_path, *dir));
           vtpm->backend_domid = atoi(tmp);
 
@@ -1875,7 +1875,7 @@ int libxl_device_vtpm_getinfo(libxl_ctx *ctx,
     dompath = libxl__xs_get_dompath(gc, domid);
     vtpminfo->devid = vtpm->devid;
 
-    vtpmpath = GCSPRINTF("%s/device/vtpm/%d", dompath, vtpminfo->devid);
+    vtpmpath = GCSPRINTF("%s/device/vtpm2/%d", dompath, vtpminfo->devid);
     vtpminfo->backend = xs_read(ctx->xsh, XBT_NULL,
           GCSPRINTF("%s/backend", vtpmpath), NULL);
     if (!vtpminfo->backend) {
diff --git a/tools/libxl/libxl_types_internal.idl 
b/tools/libxl/libxl_types_internal.idl
index c40120e..7fd43ab 100644
--- a/tools/libxl/libxl_types_internal.idl
+++ b/tools/libxl/libxl_types_internal.idl
@@ -19,7 +19,7 @@ libxl__device_kind = Enumeration("device_kind", [
     (5, "VFB"),
     (6, "VKBD"),
     (7, "CONSOLE"),
-    (8, "VTPM"),
+    (8, "VTPM2"),
     ])
 
 libxl__console_backend = Enumeration("console_backend", [
diff --git a/xen/include/public/io/tpmif.h b/xen/include/public/io/tpmif.h
index 02ccdab..7c96530 100644
--- a/xen/include/public/io/tpmif.h
+++ b/xen/include/public/io/tpmif.h
@@ -1,7 +1,7 @@
 /******************************************************************************
  * tpmif.h
  *
- * TPM I/O interface for Xen guest OSes.
+ * TPM I/O interface for Xen guest OSes, v2
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to
@@ -21,48 +21,23 @@
  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  * DEALINGS IN THE SOFTWARE.
  *
- * Copyright (c) 2005, IBM Corporation
- *
- * Author: Stefan Berger, stefanb@xxxxxxxxxx
- * Grant table support: Mahadevan Gomathisankaran
- *
- * This code has been derived from tools/libxc/xen/io/netif.h
- *
- * Copyright (c) 2003-2004, Keir Fraser
  */
 
 #ifndef __XEN_PUBLIC_IO_TPMIF_H__
 #define __XEN_PUBLIC_IO_TPMIF_H__
 
-#include "../grant_table.h"
+struct vtpm_shared_page {
+    uint32_t length;         /* request/response length in bytes */
 
-struct tpmif_tx_request {
-    unsigned long addr;   /* Machine address of packet.   */
-    grant_ref_t ref;      /* grant table access reference */
-    uint16_t unused;
-    uint16_t size;        /* Packet size in bytes.        */
-};
-typedef struct tpmif_tx_request tpmif_tx_request_t;
-
-/*
- * The TPMIF_TX_RING_SIZE defines the number of pages the
- * front-end and backend can exchange (= size of array).
- */
-typedef uint32_t TPMIF_RING_IDX;
-
-#define TPMIF_TX_RING_SIZE 1
-
-/* This structure must fit in a memory page. */
-
-struct tpmif_ring {
-    struct tpmif_tx_request req;
-};
-typedef struct tpmif_ring tpmif_ring_t;
+    uint8_t state;           /* 0 - response ready / idle
+                              * 1 - request ready / working */
+    uint8_t locality;        /* for the current request */
+    uint8_t pad;
 
-struct tpmif_tx_interface {
-    struct tpmif_ring ring[TPMIF_TX_RING_SIZE];
+    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 */
 };
-typedef struct tpmif_tx_interface tpmif_tx_interface_t;
+typedef struct vtpm_shared_page vtpm_shared_page_t;
 
 #endif
 
-- 
1.8.1


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