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Re: [Xen-devel] [PATCH 01/12] mini-os/tpm{back, front}: Change shared page ABI



I'm going to merge your linux changes into my working linux patch with the fixes that are in response to konrad's comments. Will test with this on the mini-os end and get back to you.

After that, we can look at the remaining patches.

On 03/21/2013 04:11 PM, Daniel De Graaf wrote:
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 now requires a
feature-protocol-v2 node in xenstore 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 v4: use feature-protocol-v2 nodes instead of changing the
device name; add command cancellation support to the protocol.
---
  extras/mini-os/include/tpmback.h  |   1 +
  extras/mini-os/include/tpmfront.h |   7 +-
  extras/mini-os/tpmback.c          | 161 +++++++++++++++++++-------------------
  extras/mini-os/tpmfront.c         | 143 +++++++++++++++++----------------
  xen/include/public/io/tpmif.h     |  49 ++++--------
  5 files changed, 177 insertions(+), 184 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..1398b37 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;
@@ -266,6 +263,7 @@ int insert_tpmif(tpmif_t* tpmif)
     unsigned int i, j;
     tpmif_t* tmp;
     char* err;
+   char path[512];

     local_irq_save(flags);

@@ -303,6 +301,16 @@ int insert_tpmif(tpmif_t* tpmif)

     local_irq_restore(flags);

+   snprintf(path, 512, "backend/vtpm/%u/%u/feature-protocol-v2", (unsigned int) 
tpmif->domid, tpmif->handle);
+   if ((err = xenbus_write(XBT_NIL, path, "1")))
+   {
+      /* if we got an error here we should carefully remove the interface and 
then return */
+      TPMBACK_ERR("Unable to write feature-protocol-v2 node: %s\n", err);
+      free(err);
+      remove_tpmif(tpmif);
+      goto error_post_irq;
+   }
+
     /*Listen for state changes on the new interface */
     if((err = xenbus_watch_path_token(XBT_NIL, tpmif->fe_state_path, 
tpmif->fe_state_path, &gtpmdev.events)))
     {
@@ -312,7 +320,6 @@ int insert_tpmif(tpmif_t* tpmif)
        remove_tpmif(tpmif);
        goto error_post_irq;
     }
-
     return 0;
  error:
     local_irq_restore(flags);
@@ -386,8 +393,7 @@ 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 +401,6 @@ 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);
     }
@@ -430,12 +433,6 @@ tpmif_t* new_tpmif(domid_t domid, unsigned int handle)
        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;
     }
@@ -486,7 +483,7 @@ 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);
        }

@@ -529,15 +526,27 @@ 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)
-      return;
-
-   TPMBACK_DEBUG("EVENT CHANNEL FIRE %u/%u\n", (unsigned int) tpmif->domid, 
tpmif->handle);
-   tpmif_req_ready(tpmif);
-   wake_up(&waitq);
+   vtpm_shared_page_t* pg = tpmif->page;

+   switch (pg->state)
+   {
+   case VTPM_STATE_SUBMIT:
+      TPMBACK_DEBUG("EVENT CHANNEL FIRE %u/%u\n", (unsigned int) tpmif->domid, 
tpmif->handle);
+      tpmif_req_ready(tpmif);
+      wake_up(&waitq);
+      break;
+   case VTPM_STATE_CANCEL:
+      /* If we are busy with a request, do nothing */
+      if (tpmif->flags & TPMIF_REQ_READY)
+         return;
+      /* Acknowledge the cancellation if we are idle */
+      pg->state = VTPM_STATE_IDLE;
+      notify_remote_via_evtchn(tpmif->evtchn);
+      return;
+   default:
+      /* Spurious wakeup; do nothing */
+      return;
+   }
  }

  /* Connect to frontend */
@@ -584,12 +593,25 @@ int connect_fe(tpmif_t* tpmif)
     }
     free(value);

+   /* Check that protocol v2 is being used */
+   snprintf(path, 512, "%s/feature-protocol-v2", tpmif->fe_path);
+   if((err = xenbus_read(XBT_NIL, path, &value))) {
+      TPMBACK_ERR("Unable to read %s during tpmback initialization! error = 
%s\n", path, err);
+      free(err);
+      return -1;
+   }
+   if(strcmp(value, "1")) {
+      TPMBACK_ERR("%s has an invalid value (%s)\n", path, value);
+      free(value);
+      return -1;
+   }
+   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)))
@@ -618,7 +640,7 @@ 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;
  }

@@ -874,6 +896,7 @@ 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 +907,12 @@ 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 +922,22 @@ 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 +968,24 @@ 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 +999,7 @@ 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 = VTPM_STATE_FINISH;
     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..a15b5cf 100644
--- a/extras/mini-os/tpmfront.c
+++ b/extras/mini-os/tpmfront.c
@@ -47,11 +47,21 @@

  void tpmfront_handler(evtchn_port_t port, struct pt_regs *regs, void *data) {
     struct tpmfront_dev* dev = (struct tpmfront_dev*) data;
+   vtpm_shared_page_t* shr = dev->page;
     /*If we get a response when we didnt make a request, just ignore it */
     if(!dev->waiting) {
        return;
     }

+   switch (shr->state) {
+   case VTPM_STATE_FINISH: /* request was completed */
+   case VTPM_STATE_IDLE:   /* request was cancelled */
+      break;
+   default:
+      /* Spurious wakeup; do nothing, request is still pending */
+      return;
+   }
+
     dev->waiting = 0;
  #ifdef HAVE_LIBC
     if(dev->fd >= 0) {
@@ -176,7 +186,7 @@ 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 +200,13 @@ 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 +238,7 @@ 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 +250,6 @@ 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");

@@ -279,6 +288,15 @@ struct tpmfront_dev* init_tpmfront(const char* _nodename)
        goto error;
     }

+   /* Publish protocol v2 feature */
+   snprintf(path, 512, "%s/feature-protocol-v2", dev->nodename);
+   if ((err = xenbus_write(XBT_NIL, path, "1")))
+   {
+      TPMFRONT_ERR("Unable to write feature-protocol-v2 node: %s\n", err);
+      free(err);
+      goto error;
+   }
+
     /* Create and publish grant reference and event channel */
     if (tpmfront_connect(dev)) {
        goto error;
@@ -289,18 +307,19 @@ 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) {
+   /* Ensure backend is also using protocol v2 */
+   snprintf(path, 512, "%s/feature-protocol-v2", dev->bepath);
+   if((err = xenbus_read(XBT_NIL, path, &value))) {
+      TPMFRONT_ERR("Unable to read %s during tpmfront initialization! error = 
%s\n", path, err);
+      free(err);
        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;
-      }
+   if(strcmp(value, "1")) {
+      TPMFRONT_ERR("%s has an invalid value (%s)\n", path, value);
+      free(value);
+      goto error;
     }
+   free(value);

     TPMFRONT_LOG("Initialization Completed successfully\n");

@@ -314,8 +333,6 @@ 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 +366,12 @@ 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 +389,17 @@ 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 +413,16 @@ 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 = VTPM_STATE_SUBMIT;
+
     dev->waiting = 1;
     dev->resplen = 0;
  #ifdef HAVE_LIBC
@@ -434,44 +437,44 @@ 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;

     /* Initialize */
     *msg = NULL;
     *length = 0;
+   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 (shr->state != VTPM_STATE_FINISH)
+      goto quit;
+
+   *length = shr->length;
+
+   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 +507,14 @@ 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/xen/include/public/io/tpmif.h b/xen/include/public/io/tpmif.h
index fca2c4e..ab0c652 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 +21,31 @@
   * 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 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.        */
+enum vtpm_state {
+    VTPM_STATE_IDLE,         /* no contents / vTPM idle / cancel complete */
+    VTPM_STATE_SUBMIT,       /* request ready / vTPM working */
+    VTPM_STATE_FINISH,       /* response ready / vTPM idle */
+    VTPM_STATE_CANCEL,       /* cancel requested / vTPM working */
  };
-typedef struct tpmif_tx_request tpmif_tx_request_t;
+/* The backend should only change state to IDLE or FINISH, while the
+ * frontend should only change to SUBMIT or CANCEL. */

-/*
- * 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
+struct vtpm_shared_page {
+    uint32_t length;         /* request/response length in bytes */

-/* 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;           /* enum vtpm_state */
+    uint8_t locality;        /* for the current request */
+    uint8_t pad;             /* should be zero */

-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

--
1.8.1.4



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