Re: [Xen-devel] [PATCH] drivers/tpm-xen: Change vTPM shared page ABI

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 21.03.13 at 21:12, Daniel De Graaf <dgdegra@xxxxxxxxxxxxx> wrote:
> --- a/include/xen/interface/io/tpmif.h
> +++ b/include/xen/interface/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
> @@ -21,45 +21,30 @@
>   * 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_shared_page_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 */
>  };
> -struct tpmif_tx_request;
> +/* 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).
> - */
> -#define TPMIF_TX_RING_SIZE 1
>  
> -/* This structure must fit in a memory page. */
> +struct vtpm_shared_page {
> +     uint32_t length;         /* request/response length in bytes */
>  
> -struct tpmif_ring {
> -     struct tpmif_tx_request req;
> -};
> -struct tpmif_ring;
> +     uint8_t state;           /* enum vtpm_shared_page_state */
> +     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 */
>  };
> -struct tpmif_tx_interface;
>  
>  #endif

I'm relatively certain I said this before: For one, a patch to the
master copy of this header is going to be needed. And you can't
just rip out the old interface - existing consumers must continue
to build (and work, with an old interface counterpart).

Jan


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