Re: [Qemu-devel] [PATCH V13 2/7] Add TPM (frontend) hardware interface (TPM TIS) to Qemu

[Anthony Liguori <anthony@codemonkey.ws>]

On 12/12/2011 01:12 PM, Stefan Berger wrote:
> This patch adds the main code of the TPM frontend driver, the TPM TIS
> interface, to Qemu. The code is largely based on the previous implementation
> for Xen but has been significantly extended to meet the standard's
> requirements, such as the support for changing of localities and all the
> functionality of the available flags.
>
> Communication with the backend (i.e., for Xen or the libtpms-based one)
> is cleanly separated through an interface which the backend driver needs
> to implement.
>
> The TPM TIS driver's backend was previously chosen in the code added
> to arch_init. The frontend holds a pointer to the chosen backend (interface).
>
> Communication with the backend is largely based on signals and conditions.
> Whenever the frontend has collected a complete packet, it will signal
> the backend, which then starts processing the command. Once the result
> has been returned, the backend invokes a callback function
> (tis_tpm_receive_cb()).
>
> The one tricky part is support for VM suspend while the TPM is processing
> a command. In this case the frontend driver is waiting for the backend
> to return the result of the last command before shutting down. It waits
> on a condition for a signal from the backend, which is delivered in
> tis_tpm_receive_cb().
>
> Testing the proper functioning of the different flags and localities
> cannot be done from user space when running in Linux for example, since
> access to the address space of the TPM TIS interface is not possible. Also
> the Linux driver itself does not exercise all functionality. So, for
> testing there is a fairly extensive test suite as part of the SeaBIOS patches
> since from within the BIOS one can have full access to all the TPM's registers.
>
>
> Signed-off-by: Stefan Berger<stefanb@linux.vnet.ibm.com>
>
> ---
>
> v13:
>    - don't call destroy callback in error path in tpm_tis_init
>
> v11:
>    - initialize val with 0xffffffff as default value to return from MMIO
>      read to an undefined location
>    - display size of read or write operations in debugging output
>
> v10:
>    - Use error_report where necessary
>    - Convert to use memory_region_init_io; use DEVICE_NATIVE_ENDIAN which
>      works for an x86 VM on x86 or ppc host
>    - Implement cleanup in tpm_tis_init
>    - put frontend model name into TPMBackend driver structure for later display
>      with the monitor
>
> v9:
>    - prefixing all function with tpm_tis_ and all constants with TPM_TIS_
>    - adding minimum VMStateDescription and marking device as non-migratable
>
> v5:
>    - adding comment to tis_data_read
>    - refactoring following support for split command line options
>      -tpmdev and -device
>    - code handling the configuration of the TPM device was moved to tpm.c
>    - removed empty line at end of file
>
> v3:
>    - prefixing functions with tis_
>    - added a function to the backend interface 'early_startup_tpm' that
>      allows to detect the presence of the block storage and gracefully fails
>      Qemu if it's not available. This works with migration using shared
>      storage but doesn't support migration with block storage migration.
>      For encyrypted QCoW2 and in case of a snapshot resue the late_startup_tpm
>      interface function is called
> ---
>   hw/tpm_tis.c |  818 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>   1 files changed, 818 insertions(+), 0 deletions(-)
>   create mode 100644 hw/tpm_tis.c
>
> diff --git a/hw/tpm_tis.c b/hw/tpm_tis.c
> new file mode 100644
> index 0000000..34d0043
> --- /dev/null
> +++ b/hw/tpm_tis.c
> @@ -0,0 +1,818 @@
> +/*
> + * tpm_tis.c - QEMU's TPM TIS interface emulator
> + *
> + * Copyright (C) 2006,2010,2011 IBM Corporation
> + *
> + * Authors:
> + *  Stefan Berger<stefanb@us.ibm.com>
> + *  David Safford<safford@us.ibm.com>
> + *
> + * Xen 4 support: Andrease Niederl<andreas.niederl@iaik.tugraz.at>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License as
> + * published by the Free Software Foundation, version 2 of the
> + * License.
> + *
> + *
> + * Implementation of the TIS interface according to specs found at
> + * http://www.trustedcomputiggroup.org.
> + * In the developers menu choose the PC Client section then find the TIS
> + * specification.
> + */
> +
> +#include "tpm.h"
> +#include "block.h"
> +#include "exec-memory.h"
> +#include "hw/hw.h"
> +#include "hw/pc.h"
> +#include "hw/tpm_tis.h"
> +#include "qemu-error.h"
> +
> +#include<stdio.h>


#include "qemu-common.h"

> +
> +/*#define DEBUG_TIS */
> +
> +/* whether the STS interrupt is supported */
> +/*#define RAISE_STS_IRQ */
> +
> +/* tis registers */
> +#define TPM_TIS_REG_ACCESS                0x00
> +#define TPM_TIS_REG_INT_ENABLE            0x08
> +#define TPM_TIS_REG_INT_VECTOR            0x0c
> +#define TPM_TIS_REG_INT_STATUS            0x10
> +#define TPM_TIS_REG_INTF_CAPABILITY       0x14
> +#define TPM_TIS_REG_STS                   0x18
> +#define TPM_TIS_REG_DATA_FIFO             0x24
> +#define TPM_TIS_REG_DID_VID               0xf00
> +#define TPM_TIS_REG_RID                   0xf04
> +
> +#define TPM_TIS_STS_VALID                 (1<<  7)
> +#define TPM_TIS_STS_COMMAND_READY         (1<<  6)
> +#define TPM_TIS_STS_TPM_GO                (1<<  5)
> +#define TPM_TIS_STS_DATA_AVAILABLE        (1<<  4)
> +#define TPM_TIS_STS_EXPECT                (1<<  3)
> +#define TPM_TIS_STS_RESPONSE_RETRY        (1<<  1)
> +
> +#define TPM_TIS_ACCESS_TPM_REG_VALID_STS  (1<<  7)
> +#define TPM_TIS_ACCESS_ACTIVE_LOCALITY    (1<<  5)
> +#define TPM_TIS_ACCESS_BEEN_SEIZED        (1<<  4)
> +#define TPM_TIS_ACCESS_SEIZE              (1<<  3)
> +#define TPM_TIS_ACCESS_PENDING_REQUEST    (1<<  2)
> +#define TPM_TIS_ACCESS_REQUEST_USE        (1<<  1)
> +#define TPM_TIS_ACCESS_TPM_ESTABLISHMENT  (1<<  0)
> +
> +#define TPM_TIS_INT_ENABLED               (1<<  31)
> +#define TPM_TIS_INT_DATA_AVAILABLE        (1<<  0)
> +#define TPM_TIS_INT_STS_VALID             (1<<  1)
> +#define TPM_TIS_INT_LOCALITY_CHANGED      (1<<  2)
> +#define TPM_TIS_INT_COMMAND_READY         (1<<  7)
> +
> +#ifndef RAISE_STS_IRQ
> +
> +# define TPM_TIS_INTERRUPTS_SUPPORTED (TPM_TIS_INT_LOCALITY_CHANGED | \
> +                                       TPM_TIS_INT_DATA_AVAILABLE   | \
> +                                       TPM_TIS_INT_COMMAND_READY)
> +
> +#else
> +
> +# define TPM_TIS_INTERRUPTS_SUPPORTED (TPM_TIS_INT_LOCALITY_CHANGED | \
> +                                       TPM_TIS_INT_DATA_AVAILABLE   | \
> +                                       TPM_TIS_INT_STS_VALID | \
> +                                       TPM_TIS_INT_COMMAND_READY)
> +
> +#endif
> +
> +#define TPM_TIS_CAPABILITIES_SUPPORTED   ((1<<  4) | \
> +                                          TPM_TIS_INTERRUPTS_SUPPORTED)
> +
> +#define TPM_TIS_TPM_DID       0x0001
> +#define TPM_TIS_TPM_VID       0x0001
> +#define TPM_TIS_TPM_RID       0x0001
> +
> +#define TPM_TIS_NO_DATA_BYTE  0xff
> +
> +#ifdef DEBUG_TIS
> +static void tpm_tis_show_buffer(const TPMSizedBuffer *sb, const char *string)
> +{
> +    uint16_t len;
> +
> +    len = tpm_tis_get_size_from_buffer(sb);
> +    fprintf(stderr, "tpm_tis: %s length = %d\n", string, len);
> +    tpm_dump_buffer(stderr, sb->buffer, len);
> +}
> +#endif

In the very least, move the guards into the function so that there aren't so 
many #ifdefs in the code.

> +
> +static inline uint8_t tpm_tis_locality_from_addr(target_phys_addr_t addr)
> +{
> +    return (uint8_t)((addr>>  12)&  0x7);
> +}

The compiler ignores inline for the most part.  It's just placating you by 
letting you think that you're asking it to do something :-)

> +
> +/*
> + * Send a TPM request.
> + * Call this with the state_lock held so we can sync with the receive
> + * callback.
> + */
> +static void tpm_tis_tpm_send(TPMState *s, uint8_t locty)
> +{
> +    TPMTISState *tis =&s->s.tis;
> +#ifdef DEBUG_TIS
> +    tpm_tis_show_buffer(&tis->loc[locty].w_buffer, "tpm_tis: To TPM");
> +#endif
> +    s->command_locty = locty;
> +    s->cmd_locty     =&tis->loc[locty];
> +
> +    /* w_offset serves as length indicator for length of data;
> +       it's reset when the response comes back */
> +    tis->loc[locty].state = TPM_TIS_STATE_EXECUTION;
> +    tis->loc[locty].sts&= ~TPM_TIS_STS_EXPECT;
> +
> +    s->to_tpm_execute = true;
> +    qemu_cond_signal(&s->to_tpm_cond);

The locking seems to presume that the device model is re-entrant which it's not 
today.  Am I missing something here?

> +}
> +
> +/* raise an interrupt if allowed */
> +static void tpm_tis_raise_irq(TPMState *s, uint8_t locty, uint32_t irqmask)
> +{
> +    TPMTISState *tis =&s->s.tis;
> +
> +    if (!TPM_TIS_IS_VALID_LOCTY(locty)) {
> +        return;
> +    }
> +
> +    if ((tis->loc[locty].inte&  TPM_TIS_INT_ENABLED)&&
> +        (tis->loc[locty].inte&  irqmask)) {
> +#ifdef DEBUG_TIS
> +        fprintf(stderr, "tpm_tis: Raising IRQ for flag %08x\n", irqmask);
> +#endif

I'd much prefer a dprintf.

> +        qemu_irq_raise(s->s.tis.irq);
> +        tis->loc[locty].ints |= irqmask;
> +    }
> +}
> +
> +static uint32_t tpm_tis_check_request_use_except(TPMState *s, uint8_t locty)
> +{
> +    uint8_t l;
> +
> +    for (l = 0; l<  TPM_TIS_NUM_LOCALITIES; l++) {
> +        if (l == locty) {
> +            continue;
> +        }
> +        if ((s->s.tis.loc[l].access&  TPM_TIS_ACCESS_REQUEST_USE)) {
> +            return 1;
> +        }
> +    }
> +
> +    return 0;
> +}
> +
> +static void tpm_tis_new_active_locality(TPMState *s, uint8_t new_active_locty)
> +{
> +    TPMTISState *tis =&s->s.tis;
> +    int change = (s->s.tis.active_locty != new_active_locty);
> +
> +    if (change&&  TPM_TIS_IS_VALID_LOCTY(s->s.tis.active_locty)) {
> +        /* reset flags on the old active locality */
> +        tis->loc[s->s.tis.active_locty].access&=
> +                 ~(TPM_TIS_ACCESS_ACTIVE_LOCALITY|TPM_TIS_ACCESS_REQUEST_USE);
> +        if (TPM_TIS_IS_VALID_LOCTY(new_active_locty)&&
> +            tis->loc[new_active_locty].access&  TPM_TIS_ACCESS_SEIZE) {
> +            tis->loc[tis->active_locty].access |= TPM_TIS_ACCESS_BEEN_SEIZED;
> +        }
> +    }
> +
> +    tis->active_locty = new_active_locty;
> +#ifdef DEBUG_TIS
> +    fprintf(stderr, "tpm_tis: Active locality is now %d\n",
> +            s->s.tis.active_locty);
> +#endif
> +
> +    if (TPM_TIS_IS_VALID_LOCTY(new_active_locty)) {
> +        /* set flags on the new active locality */
> +        tis->loc[new_active_locty].access |= TPM_TIS_ACCESS_ACTIVE_LOCALITY;
> +        tis->loc[new_active_locty].access&= ~(TPM_TIS_ACCESS_REQUEST_USE |
> +                                               TPM_TIS_ACCESS_SEIZE);
> +    }
> +
> +    if (change) {
> +        tpm_tis_raise_irq(s, tis->active_locty, TPM_TIS_INT_LOCALITY_CHANGED);
> +    }
> +}
> +
> +/* abort -- this function switches the locality */
> +static void tpm_tis_abort(TPMState *s, uint8_t locty)
> +{
> +    TPMTISState *tis =&s->s.tis;
> +
> +    tis->loc[locty].r_offset = 0;
> +    tis->loc[locty].w_offset = 0;
> +
> +#ifdef DEBUG_TIS
> +    fprintf(stderr, "tpm_tis: tis_abort: new active locality is %d\n",
> +            tis->next_locty);
> +#endif
> +
> +    /*
> +     * Need to react differently depending on who's aborting now and
> +     * which locality will become active afterwards.
> +     */
> +    if (tis->aborting_locty == tis->next_locty) {
> +        tis->loc[tis->aborting_locty].state = TPM_TIS_STATE_READY;
> +        tis->loc[tis->aborting_locty].sts   = TPM_TIS_STS_COMMAND_READY;
> +        tpm_tis_raise_irq(s, tis->aborting_locty, TPM_TIS_INT_COMMAND_READY);
> +    }
> +
> +    /* locality after abort is another one than the current one */
> +    tpm_tis_new_active_locality(s, tis->next_locty);
> +
> +    tis->next_locty = TPM_TIS_NO_LOCALITY;
> +    /* nobody's aborting a command anymore */
> +    tis->aborting_locty = TPM_TIS_NO_LOCALITY;
> +}
> +
> +/* prepare aborting current command */
> +static void tpm_tis_prep_abort(TPMState *s, uint8_t locty, uint8_t newlocty)
> +{
> +    TPMTISState *tis =&s->s.tis;
> +    uint8_t busy_locty;
> +
> +    tis->aborting_locty = locty;
> +    tis->next_locty = newlocty;  /* locality after successful abort */
> +
> +    /*
> +     * only abort a command using an interrupt if currently executing
> +     * a command AND if there's a valid connection to the vTPM.
> +     */
> +    for (busy_locty = 0; busy_locty<  TPM_TIS_NUM_LOCALITIES; busy_locty++) {
> +        if (tis->loc[busy_locty].state == TPM_TIS_STATE_EXECUTION) {
> +            /* there is currently no way to interrupt the TPM's operations
> +               while it's executing a command; once the TPM is done and
> +               returns the buffer, it will switch to the next_locty; */
> +#ifdef DEBUG_TIS
> +            fprintf(stderr, "tpm_tis: Locality %d is busy - "
> +                            "deferring abort\n", busy_locty);
> +#endif
> +            return;
> +        }
> +    }
> +
> +    tpm_tis_abort(s, locty);
> +}
> +
> +/*
> + * Callback from the TPM to indicate that the response was received.
> + */
> +static void tpm_tis_receive_cb(TPMState *s, uint8_t locty)
> +{
> +    TPMTISState *tis =&s->s.tis;
> +
> +    qemu_mutex_lock(&s->state_lock);
> +
> +    tis->loc[locty].sts = TPM_TIS_STS_VALID | TPM_TIS_STS_DATA_AVAILABLE;
> +    tis->loc[locty].state = TPM_TIS_STATE_COMPLETION;
> +    tis->loc[locty].r_offset = 0;
> +    tis->loc[locty].w_offset = 0;
> +
> +    if (TPM_TIS_IS_VALID_LOCTY(tis->next_locty)) {
> +        tpm_tis_abort(s, locty);
> +    }
> +
> +    qemu_cond_signal(&s->from_tpm_cond);
> +
> +    qemu_mutex_unlock(&s->state_lock);
> +
> +#ifndef RAISE_STS_IRQ
> +    tpm_tis_raise_irq(s, locty, TPM_TIS_INT_DATA_AVAILABLE);
> +#else
> +    tpm_tis_raise_irq(s, locty,
> +                      TPM_TIS_INT_DATA_AVAILABLE | TPM_TIS_INT_STS_VALID);
> +#endif
> +}
> +
> +/*
> + * read a byte of response data
> + * call this with s->state_lock held
> + */
> +static uint32_t tpm_tis_data_read(TPMState *s, uint8_t locty)
> +{
> +    TPMTISState *tis =&s->s.tis;
> +    uint32_t ret = TPM_TIS_NO_DATA_BYTE;
> +    uint16_t len;
> +
> +    if ((tis->loc[locty].sts&  TPM_TIS_STS_DATA_AVAILABLE)) {
> +        len = tpm_tis_get_size_from_buffer(&tis->loc[locty].r_buffer);
> +
> +        ret = tis->loc[locty].r_buffer.buffer[tis->loc[locty].r_offset++];
> +        if (tis->loc[locty].r_offset>= len) {
> +            /* got last byte */
> +            tis->loc[locty].sts = TPM_TIS_STS_VALID;
> +#ifdef RAISE_STS_IRQ
> +            tpm_tis_raise_irq(s, locty, TPM_TIS_INT_STS_VALID);
> +#endif
> +        }
> +#ifdef DEBUG_TIS
> +        fprintf(stderr, "tpm_tis: tpm_tis_data_read byte 0x%02x   [%d]\n",
> +                ret, tis->loc[locty].r_offset-1);
> +#endif
> +    }
> +
> +    return ret;
> +}
> +
> +/*
> + * Read a register of the TIS interface
> + * See specs pages 33-63 for description of the registers
> + */
> +static uint64_t tpm_tis_mmio_read(void *opaque, target_phys_addr_t addr,
> +                                  unsigned size)
> +{
> +    TPMState *s = opaque;
> +    TPMTISState *tis =&s->s.tis;
> +    uint16_t offset = addr&  0xffc;
> +    uint8_t shift = (addr&  0x3) * 8;
> +    uint32_t val = 0xffffffff;
> +    uint8_t locty = tpm_tis_locality_from_addr(addr);
> +
> +    qemu_mutex_lock(&s->state_lock);
> +
> +    if (s->be_driver->ops->had_startup_error(s->be_driver)) {
> +        qemu_mutex_unlock(&s->state_lock);
> +        return val;
> +    }
> +
> +    switch (offset) {
> +    case TPM_TIS_REG_ACCESS:
> +        /* never show the SEIZE flag even though we use it internally */
> +        val = tis->loc[locty].access&  ~TPM_TIS_ACCESS_SEIZE;
> +        /* the pending flag is alawys calculated */
> +        if (tpm_tis_check_request_use_except(s, locty)) {
> +            val |= TPM_TIS_ACCESS_PENDING_REQUEST;
> +        }
> +        val |= !s->be_driver->ops->get_tpm_established_flag(s->be_driver);
> +        break;
> +    case TPM_TIS_REG_INT_ENABLE:
> +        val = tis->loc[locty].inte;
> +        break;
> +    case TPM_TIS_REG_INT_VECTOR:
> +        val = tis->irq_num;
> +        break;
> +    case TPM_TIS_REG_INT_STATUS:
> +        val = tis->loc[locty].ints;
> +        break;
> +    case TPM_TIS_REG_INTF_CAPABILITY:
> +        val = TPM_TIS_CAPABILITIES_SUPPORTED;
> +        break;
> +    case TPM_TIS_REG_STS:
> +        if (tis->active_locty == locty) {
> +            if ((tis->loc[locty].sts&  TPM_TIS_STS_DATA_AVAILABLE)) {
> +                val =  (tpm_tis_get_size_from_buffer(&tis->loc[locty].r_buffer)
> +                        - tis->loc[locty].r_offset)<<  8 | tis->loc[locty].sts;
> +            } else {
> +                val = (tis->loc[locty].w_buffer.size -
> +                       tis->loc[locty].w_offset)<<  8 | tis->loc[locty].sts;
> +            }
> +        }
> +        break;
> +    case TPM_TIS_REG_DATA_FIFO:
> +        if (tis->active_locty == locty) {
> +            switch (tis->loc[locty].state) {
> +            case TPM_TIS_STATE_COMPLETION:
> +                val = tpm_tis_data_read(s, locty);
> +                break;
> +            default:
> +                val = TPM_TIS_NO_DATA_BYTE;
> +                break;
> +            }
> +        }
> +        break;
> +    case TPM_TIS_REG_DID_VID:
> +        val = (TPM_TIS_TPM_DID<<  16) | TPM_TIS_TPM_VID;
> +        break;
> +    case TPM_TIS_REG_RID:
> +        val = TPM_TIS_TPM_RID;
> +        break;
> +    }
> +
> +    qemu_mutex_unlock(&s->state_lock);
> +
> +    if (shift) {
> +        val>>= shift;
> +    }
> +
> +#ifdef DEBUG_TIS
> +    fprintf(stderr, "tpm_tis:  read.%u(%08x) = %08x\n",
> +            size, (int)addr, (uint32_t)val);
> +#endif
> +
> +    return val;
> +}
> +
> +/*
> + * Write a value to a register of the TIS interface
> + * See specs pages 33-63 for description of the registers
> + */
> +static void tpm_tis_mmio_write_intern(void *opaque, target_phys_addr_t addr,
> +                                      uint64_t val, unsigned size,
> +                                      bool hw_access)
> +{
> +    TPMState *s = opaque;
> +    TPMTISState *tis =&s->s.tis;
> +    uint16_t off = addr&  0xfff;
> +    uint8_t locty = tpm_tis_locality_from_addr(addr);
> +    uint8_t active_locty, l;
> +    int c, set_new_locty = 1;
> +    uint16_t len;
> +
> +#ifdef DEBUG_TIS
> +    fprintf(stderr, "tpm_tis: write.%u(%08x) = %08x\n",
> +            size, (int)addr, (uint32_t)val);
> +#endif
> +
> +    qemu_mutex_lock(&s->state_lock);
> +
> +    if (s->be_driver->ops->had_startup_error(s->be_driver)) {
> +        qemu_mutex_unlock(&s->state_lock);
> +        return;
> +    }
> +
> +    switch (off) {
> +    case TPM_TIS_REG_ACCESS:
> +
> +        if ((val&  TPM_TIS_ACCESS_SEIZE)) {
> +            val&= ~(TPM_TIS_ACCESS_REQUEST_USE |
> +                     TPM_TIS_ACCESS_ACTIVE_LOCALITY);
> +        }
> +
> +        active_locty = tis->active_locty;
> +
> +        if ((val&  TPM_TIS_ACCESS_ACTIVE_LOCALITY)) {
> +            /* give up locality if currently owned */
> +            if (tis->active_locty == locty) {
> +#ifdef DEBUG_TIS
> +                fprintf(stderr, "tpm_tis: Releasing locality %d\n", locty);
> +#endif
> +                uint8_t newlocty = TPM_TIS_NO_LOCALITY;
> +                /* anybody wants the locality ? */
> +                for (c = TPM_TIS_NUM_LOCALITIES - 1; c>= 0; c--) {
> +                    if ((tis->loc[c].access&  TPM_TIS_ACCESS_REQUEST_USE)) {
> +#ifdef DEBUG_TIS
> +                        fprintf(stderr, "tpm_tis: Locality %d requests use.\n",
> +                                c);
> +#endif
> +                        newlocty = c;
> +                        break;
> +                    }
> +                }
> +#ifdef DEBUG_TIS
> +                fprintf(stderr, "tpm_tis: TPM_TIS_ACCESS_ACTIVE_LOCALITY: "
> +                                "Next active locality: %d\n",
> +                                newlocty);
> +#endif
> +                if (TPM_TIS_IS_VALID_LOCTY(newlocty)) {
> +                    set_new_locty = 0;
> +                    tpm_tis_prep_abort(s, locty, newlocty);
> +                } else {
> +                    active_locty = TPM_TIS_NO_LOCALITY;
> +                }
> +            } else {
> +                /* not currently the owner; clear a pending request */
> +                tis->loc[locty].access&= ~TPM_TIS_ACCESS_REQUEST_USE;
> +            }
> +        }
> +
> +        if ((val&  TPM_TIS_ACCESS_BEEN_SEIZED)) {
> +            tis->loc[locty].access&= ~TPM_TIS_ACCESS_BEEN_SEIZED;
> +        }
> +
> +        if ((val&  TPM_TIS_ACCESS_SEIZE)) {
> +            /* allow seize if a locality is active and the requesting
> +               locality is higher than the one that's active
> +               OR
> +               allow seize for requesting locality if no locality is
> +               active */
> +            while ((TPM_TIS_IS_VALID_LOCTY(tis->active_locty)&&
> +                    locty>  tis->active_locty) ||
> +                   (!TPM_TIS_IS_VALID_LOCTY(tis->active_locty))) {
> +
> +                /* already a pending SEIZE ? */
> +                if ((tis->loc[locty].access&  TPM_TIS_ACCESS_SEIZE)) {
> +                    break;
> +                }
> +
> +                /* check for ongoing seize by a higher locality */
> +                for (l = locty + 1; l<  TPM_TIS_NUM_LOCALITIES; l++) {
> +                    if ((tis->loc[l].access&  TPM_TIS_ACCESS_SEIZE)) {
> +                        break;
> +                    }
> +                }
> +
> +                /* cancel any seize by a lower locality */
> +                for (l = 0; l<  locty - 1; l++) {
> +                    tis->loc[l].access&= ~TPM_TIS_ACCESS_SEIZE;
> +                }
> +
> +                tis->loc[locty].access |= TPM_TIS_ACCESS_SEIZE;
> +#ifdef DEBUG_TIS
> +                fprintf(stderr, "tpm_tis: TPM_TIS_ACCESS_SEIZE: "
> +                                "Locality %d seized from locality %d\n",
> +                                locty, tis->active_locty);
> +                fprintf(stderr,
> +                        "tpm_tis: TPM_TIS_ACCESS_SEIZE: Initiating abort.\n");
> +#endif
> +                set_new_locty = 0;
> +                tpm_tis_prep_abort(s, tis->active_locty, locty);
> +                break;
> +            }
> +        }
> +
> +        if ((val&  TPM_TIS_ACCESS_REQUEST_USE)) {
> +            if (tis->active_locty != locty) {
> +                if (TPM_TIS_IS_VALID_LOCTY(tis->active_locty)) {
> +                    tis->loc[locty].access |= TPM_TIS_ACCESS_REQUEST_USE;
> +                } else {
> +                    /* no locality active ->  make this one active now */
> +                    active_locty = locty;
> +                }
> +            }
> +        }
> +
> +        if (set_new_locty) {
> +            tpm_tis_new_active_locality(s, active_locty);
> +        }
> +
> +        break;
> +    case TPM_TIS_REG_INT_ENABLE:
> +        if (tis->active_locty != locty) {
> +            break;
> +        }
> +
> +        tis->loc[locty].inte = (val&  (TPM_TIS_INT_ENABLED | (0x3<<  3) |
> +                                     TPM_TIS_INTERRUPTS_SUPPORTED));
> +        break;
> +    case TPM_TIS_REG_INT_VECTOR:
> +        /* hard wired -- ignore */
> +        break;
> +    case TPM_TIS_REG_INT_STATUS:
> +        if (tis->active_locty != locty) {
> +            break;
> +        }
> +
> +        /* clearing of interrupt flags */
> +        if (((val&  TPM_TIS_INTERRUPTS_SUPPORTED))&&
> +            (tis->loc[locty].ints&  TPM_TIS_INTERRUPTS_SUPPORTED)) {
> +            tis->loc[locty].ints&= ~val;
> +            if (tis->loc[locty].ints == 0) {
> +                qemu_irq_lower(tis->irq);
> +#ifdef DEBUG_TIS
> +                fprintf(stderr, "tpm_tis: Lowering IRQ\n");
> +#endif
> +            }
> +        }
> +        tis->loc[locty].ints&= ~(val&  TPM_TIS_INTERRUPTS_SUPPORTED);
> +        break;
> +    case TPM_TIS_REG_STS:
> +        if (tis->active_locty != locty) {
> +            break;
> +        }
> +
> +        val&= (TPM_TIS_STS_COMMAND_READY | TPM_TIS_STS_TPM_GO |
> +                TPM_TIS_STS_RESPONSE_RETRY);
> +
> +        if (val == TPM_TIS_STS_COMMAND_READY) {
> +            switch (tis->loc[locty].state) {
> +
> +            case TPM_TIS_STATE_READY:
> +                tis->loc[locty].w_offset = 0;
> +                tis->loc[locty].r_offset = 0;
> +            break;
> +
> +            case TPM_TIS_STATE_IDLE:
> +                tis->loc[locty].sts   = TPM_TIS_STS_COMMAND_READY;
> +                tis->loc[locty].state = TPM_TIS_STATE_READY;
> +                tpm_tis_raise_irq(s, locty, TPM_TIS_INT_COMMAND_READY);
> +            break;
> +
> +            case TPM_TIS_STATE_EXECUTION:
> +            case TPM_TIS_STATE_RECEPTION:
> +                /* abort currently running command */
> +#ifdef DEBUG_TIS
> +                fprintf(stderr, "tpm_tis: %s: Initiating abort.\n",
> +                        __func__);
> +#endif
> +                tpm_tis_prep_abort(s, locty, locty);
> +            break;
> +
> +            case TPM_TIS_STATE_COMPLETION:
> +                tis->loc[locty].w_offset = 0;
> +                tis->loc[locty].r_offset = 0;
> +                /* shortcut to ready state with C/R set */
> +                tis->loc[locty].state = TPM_TIS_STATE_READY;
> +                if (!(tis->loc[locty].sts&  TPM_TIS_STS_COMMAND_READY)) {
> +                    tis->loc[locty].sts   = TPM_TIS_STS_COMMAND_READY;
> +                    tpm_tis_raise_irq(s, locty, TPM_TIS_INT_COMMAND_READY);
> +                }
> +            break;
> +
> +            }
> +        } else if (val == TPM_TIS_STS_TPM_GO) {
> +            switch (tis->loc[locty].state) {
> +            case TPM_TIS_STATE_RECEPTION:
> +                tpm_tis_tpm_send(s, locty);
> +                break;
> +            default:
> +                /* ignore */
> +                break;
> +            }
> +        } else if (val == TPM_TIS_STS_RESPONSE_RETRY) {
> +            switch (tis->loc[locty].state) {
> +            case TPM_TIS_STATE_COMPLETION:
> +                tis->loc[locty].r_offset = 0;
> +                tis->loc[locty].sts = TPM_TIS_STS_VALID |
> +                                      TPM_TIS_STS_DATA_AVAILABLE;
> +                break;
> +            default:
> +                /* ignore */
> +                break;
> +            }
> +        }
> +        break;
> +    case TPM_TIS_REG_DATA_FIFO:
> +        /* data fifo */
> +        if (tis->active_locty != locty) {
> +            break;
> +        }
> +
> +        if (tis->loc[locty].state == TPM_TIS_STATE_IDLE ||
> +            tis->loc[locty].state == TPM_TIS_STATE_EXECUTION ||
> +            tis->loc[locty].state == TPM_TIS_STATE_COMPLETION) {
> +            /* drop the byte */
> +        } else {
> +#ifdef DEBUG_TIS
> +            fprintf(stderr, "tpm_tis: Byte to send to TPM: %02x\n",
> +                    (uint8_t)val);
> +#endif
> +            if (tis->loc[locty].state == TPM_TIS_STATE_READY) {
> +                tis->loc[locty].state = TPM_TIS_STATE_RECEPTION;
> +                tis->loc[locty].sts = TPM_TIS_STS_EXPECT | TPM_TIS_STS_VALID;
> +            }
> +
> +            if ((tis->loc[locty].sts&  TPM_TIS_STS_EXPECT)) {
> +                if (tis->loc[locty].w_offset<  tis->loc[locty].w_buffer.size) {
> +                    tis->loc[locty].w_buffer.
> +                        buffer[tis->loc[locty].w_offset++] = (uint8_t)val;
> +                } else {
> +                    tis->loc[locty].sts = TPM_TIS_STS_VALID;
> +                }
> +            }
> +
> +            /* check for complete packet */
> +            if (tis->loc[locty].w_offset>  5&&
> +                (tis->loc[locty].sts&  TPM_TIS_STS_EXPECT)) {
> +                /* we have a packet length - see if we have all of it */
> +#ifdef RAISE_STS_IRQ
> +                bool needIrq = !(tis->loc[locty].sts&  TPM_TIS_STS_VALID);
> +#endif
> +                len = tpm_tis_get_size_from_buffer(&tis->loc[locty].w_buffer);
> +                if (len>  tis->loc[locty].w_offset) {
> +                    tis->loc[locty].sts = TPM_TIS_STS_EXPECT |
> +                                          TPM_TIS_STS_VALID;
> +                } else {
> +                    /* packet complete */
> +                    tis->loc[locty].sts = TPM_TIS_STS_VALID;
> +                }
> +#ifdef RAISE_STS_IRQ
> +                if (needIrq) {
> +                    tpm_tis_raise_irq(s, locty, TPM_TIS_INT_STS_VALID);
> +                }
> +#endif
> +            }
> +        }
> +        break;
> +    }
> +
> +    qemu_mutex_unlock(&s->state_lock);
> +}
> +
> +static void tpm_tis_mmio_write(void *opaque, target_phys_addr_t addr,
> +                               uint64_t val, unsigned size)
> +{
> +    return tpm_tis_mmio_write_intern(opaque, addr, val, size, false);
> +}
> +
> +static const MemoryRegionOps tpm_tis_memory_ops = {
> +    .read = tpm_tis_mmio_read,
> +    .write = tpm_tis_mmio_write,
> +    .endianness = DEVICE_NATIVE_ENDIAN,
> +    .valid = {
> +        .min_access_size = 1,
> +        .max_access_size = 4,
> +    },
> +};
> +
> +static int tpm_tis_do_startup_tpm(TPMState *s)
> +{
> +    return s->be_driver->ops->startup_tpm(s->be_driver);
> +}
> +
> +/*
> + * This function is called when the machine starts, resets or due to
> + * S3 resume.
> + */
> +static void tpm_tis_reset(DeviceState *d)
> +{
> +    TPMState *s = container_of(d, TPMState, busdev.qdev);
> +    TPMTISState *tis =&s->s.tis;
> +    int c;
> +
> +    s->tpm_initialized = false;
> +
> +    s->be_driver->ops->reset(s->be_driver);
> +
> +    tis->active_locty = TPM_TIS_NO_LOCALITY;
> +    tis->next_locty = TPM_TIS_NO_LOCALITY;
> +    tis->aborting_locty = TPM_TIS_NO_LOCALITY;
> +
> +    for (c = 0; c<  TPM_TIS_NUM_LOCALITIES; c++) {
> +        tis->loc[c].access = TPM_TIS_ACCESS_TPM_REG_VALID_STS;
> +        tis->loc[c].sts = 0;
> +        tis->loc[c].inte = (1<<  3);
> +        tis->loc[c].ints = 0;
> +        tis->loc[c].state = TPM_TIS_STATE_IDLE;
> +
> +        tis->loc[c].w_offset = 0;
> +        s->be_driver->ops->realloc_buffer(&tis->loc[c].w_buffer);
> +        tis->loc[c].r_offset = 0;
> +        s->be_driver->ops->realloc_buffer(&tis->loc[c].r_buffer);
> +    }
> +
> +    tpm_tis_do_startup_tpm(s);
> +}
> +
> +static int tpm_tis_init(ISADevice *dev)
> +{
> +    TPMState *s = DO_UPCAST(TPMState, busdev, dev);
> +    TPMTISState *tis =&s->s.tis;
> +    int rc;
> +
> +    qemu_mutex_init(&s->state_lock);
> +    qemu_cond_init(&s->from_tpm_cond);
> +    qemu_cond_init(&s->to_tpm_cond);
> +
> +    s->be_driver = qemu_find_tpm(s->backend);
> +    if (!s->be_driver) {
> +        error_report("tpm_tis: backend driver with id %s could not be "
> +                     "found.n\n", s->backend);
> +        return -1;
> +    }
> +
> +    s->be_driver->fe_model = "tpm-tis";
> +
> +    if (s->be_driver->ops->init(s->be_driver, s, tpm_tis_receive_cb)) {
> +        return -1;
> +    }
> +
> +    isa_init_irq(dev,&tis->irq, tis->irq_num);
> +
> +    memory_region_init_io(&s->mmio,&tpm_tis_memory_ops, s, "tpm-tis-mmio",
> +                          0x1000 * TPM_TIS_NUM_LOCALITIES);
> +    memory_region_add_subregion(get_system_memory(), TPM_TIS_ADDR_BASE,
> +&s->mmio);
> +
> +    rc = tpm_tis_do_startup_tpm(s);
> +    if (rc != 0) {
> +        goto err_destroy_memory;
> +    }
> +
> +    return 0;
> +
> + err_destroy_memory:
> +    memory_region_destroy(&s->mmio);
> +
> +    return -1;
> +}
> +
> +static const VMStateDescription vmstate_tpm_tis = {
> +    .name = "tpm",
> +    .unmigratable = 1,
> +};
> +
> +static ISADeviceInfo tpm_tis_device_info = {
> +    .init         = tpm_tis_init,
> +    .qdev.name    = "tpm-tis",
> +    .qdev.size    = sizeof(TPMState),
> +    .qdev.vmsd    =&vmstate_tpm_tis,
> +    .qdev.reset   = tpm_tis_reset,
> +    .qdev.props = (Property[]) {
> +        DEFINE_PROP_UINT32("irq", TPMState,
> +                           s.tis.irq_num, TPM_TIS_IRQ),
> +        DEFINE_PROP_STRING("tpmdev", TPMState, backend),
> +        DEFINE_PROP_END_OF_LIST(),
> +    },
> +};
> +
> +static void tpm_tis_register_device(void)
> +{
> +    isa_qdev_register(&tpm_tis_device_info);
> +}
> +
> +device_init(tpm_tis_register_device)