tpm_tis.c

xen虚拟机源代码安装包

/* raise an interrupt if allowed */
static void tis_raise_irq(tpmState *s, uint8_t locty, uint32_t irqmask)
{
    if (!s->irq_pending &&
        (s->loc[locty].inte & INT_ENABLED) &&
        (s->loc[locty].inte & irqmask)) {
        if ((irqmask & s->loc[locty].ints) == 0) {
#ifdef DEBUG_TPM
            fprintf(logfile,"Raising IRQ for flag %08x\n",irqmask);
#endif
            s->set_irq(s->irq_opaque, s->irq, 1);
            s->irq_pending = 1;
            s->loc[locty].ints |= irqmask;
        }
    }
}

/* abort execution of command */
static void tis_abort(tpmState *s)
{
    s->offset = 0;
    s->active_loc = s->next_locty;

    /*
     * Need to react differently depending on who's aborting now and
     * which locality will become active afterwards.
     */
    if (s->aborting_locty == s->next_locty) {
        s->loc[s->aborting_locty].state = STATE_READY;
        s->loc[s->aborting_locty].sts   = STS_COMMAND_READY;
        tis_raise_irq(s, s->aborting_locty, INT_COMMAND_READY);
    }

    /* locality after abort is another one than the current one */
    if (s->aborting_locty != s->next_locty && s->next_locty != NO_LOCALITY) {
        s->loc[s->aborting_locty].access &= ~ACCESS_ACTIVE_LOCALITY;
        s->loc[s->next_locty].access     |=  ACCESS_ACTIVE_LOCALITY;
        tis_raise_irq(s, s->next_locty, INT_LOCALITY_CHANGED);
    }

    s->aborting_locty = NO_LOCALITY; /* nobody's aborting a command anymore */

    qemu_del_timer(s->poll_timer);
}

/* abort current command */
static void tis_prep_abort(tpmState *s, uint8_t locty, uint8_t newlocty)
{
    s->aborting_locty = locty; /* current locality */
    s->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.
     */
    if (s->loc[locty].state == STATE_EXECUTION &&
        IS_COMM_WITH_VTPM(s)) {
        /* start timer and inside the timer wait for the result */
        s->poll_attempts = 0;
        tis_prep_next_interrupt(s);
    } else {
        tis_abort(s);
    }
}


/*
 * Try to receive a response from the vTPM
 */
static void tis_attempt_receive(tpmState *s, uint8_t locty)
{
    /*
     * Attempt to read from the vTPM here if
     * - not aborting a command
     * - command has been sent and state is 'EXECUTION' now
     * - no data are already available (data have already been read)
     * - there's a communication path to the vTPM established
     */
    if (!IS_VALID_LOC(s->aborting_locty)) {
        if (s->loc[locty].state == STATE_EXECUTION) {
            if (0 == (s->loc[locty].sts & STS_DATA_AVAILABLE)){
                if (IS_COMM_WITH_VTPM(s)) {
                    int n = TPM_Receive(s, &s->buffer);
                    if (n > 0) {
                        s->loc[locty].sts = STS_VALID | STS_DATA_AVAILABLE;
                        s->loc[locty].state = STATE_COMPLETION;
                        close_vtpm_channel(s, FORCE_CLOSE);
                        tis_raise_irq(s, locty, INT_DATA_AVAILABLE);
                    }
                }
            }
        }
    }
}

/*
 * Read a register of the TIS interface
 * See specs pages 33-63 for description of the registers
 */
static uint32_t tis_mem_readl(void *opaque, target_phys_addr_t addr)
{
    tpmState *s = (tpmState *)opaque;
    uint16_t offset = addr & 0xffc;
    uint8_t shift = (addr & 0x3) * 8;
    uint32_t val = 0;
    uint8_t locty = locality_from_addr(addr);

    if (offset == TPM_REG_ACCESS) {
        if (s->active_loc == locty) {
            s->loc[locty].access |= (1 << 5);
         } else {
            s->loc[locty].access &= ~(1 << 5);
        }
        val = s->loc[locty].access;
    } else
    if (offset == TPM_REG_INT_ENABLE) {
        val = s->loc[locty].inte;
    } else
    if (offset == TPM_REG_INT_VECTOR) {
        val = s->irq;
    } else
    if (offset == TPM_REG_INT_STATUS) {
        tis_attempt_receive(s, locty);
        val = s->loc[locty].ints;
    } else
    if (offset == TPM_REG_INTF_CAPABILITY) {
        val = CAPABILITIES_SUPPORTED;
    } else
    if (offset == TPM_REG_STS) { /* status register */
        tis_attempt_receive(s, locty);
        val = (sizeof(s->buffer.buf) - s->offset) << 8 | s->loc[locty].sts;
    } else
    if (offset == TPM_REG_DATA_FIFO) {
      val = tpm_data_read(s, locty);
    } else
    if (offset == TPM_REG_DID_VID) {
        val = (TPM_DID << 16) | TPM_VID;
    } else
    if (offset == TPM_REG_RID) {
         val = TPM_RID;
    }

    if (shift)
        val >>= shift;

#ifdef DEBUG_TPM
    fprintf(logfile," read(%08x) = %08x\n",
            (int)addr,
            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 tis_mem_writel(void *opaque, target_phys_addr_t addr, uint32_t val)
{
    tpmState* s=(tpmState*)opaque;
    uint16_t off = addr & 0xfff;
    uint8_t locty = locality_from_addr(addr);
    int n, c;
    uint32_t len;

#ifdef DEBUG_TPM
    fprintf(logfile,"write(%08x) = %08x\n",
            (int)addr,
            val);
#endif

    if (off == TPM_REG_ACCESS) {
        if (val & ACCESS_ACTIVE_LOCALITY) {
            /* give up locality if currently owned */
            if (s->active_loc == locty) {
                uint8_t newlocty = NO_LOCALITY;
                s->loc[locty].access &= ~(ACCESS_PENDING_REQUEST);
                /* anybody wants the locality ? */
                for (c = NUM_LOCALITIES - 1; c >= 0; c--) {
                    if (s->loc[c].access & ACCESS_REQUEST_USE) {
                        s->loc[c].access |= ACCESS_TPM_REG_VALID_STS;
                        s->loc[c].access &= ~ACCESS_REQUEST_USE;
                        newlocty = c;
                        break;
                    }
                }
                tis_prep_abort(s, locty, newlocty);
            }
        }
        if (val & ACCESS_BEEN_SEIZED) {
            /* clear the flag */
            s->loc[locty].access &= ~ACCESS_BEEN_SEIZED;
        }
        if (val & ACCESS_SEIZE) {
            if (locty > s->active_loc && IS_VALID_LOC(s->active_loc)) {
                s->loc[s->active_loc].access |= ACCESS_BEEN_SEIZED;
                s->loc[locty].access = ACCESS_TPM_REG_VALID_STS;
                tis_prep_abort(s, s->active_loc, locty);
            }
        }
        if (val & ACCESS_REQUEST_USE) {
            if (IS_VALID_LOC(s->active_loc)) {
                /* locality election */
                s->loc[s->active_loc].access |= ACCESS_PENDING_REQUEST;
            } else {
                /* no locality active -> make this one active now */
                s->loc[locty].access |= ACCESS_ACTIVE_LOCALITY;
                s->active_loc = locty;
                tis_raise_irq(s, locty, INT_LOCALITY_CHANGED);
            }
        }
    } else
    if (off == TPM_REG_INT_ENABLE) {
        s->loc[locty].inte = (val & (INT_ENABLED | (0x3 << 3) |
                                     INTERRUPTS_SUPPORTED));
    } else
    if (off == TPM_REG_INT_STATUS) {
        /* clearing of interrupt flags */
        if ((val & INTERRUPTS_SUPPORTED) &&
            (s->loc[locty].ints & INTERRUPTS_SUPPORTED)) {
            s->set_irq(s->irq_opaque, s->irq, 0);
            s->irq_pending = 0;
        }
        s->loc[locty].ints &= ~(val & INTERRUPTS_SUPPORTED);
    } else
    if (off == TPM_REG_STS) {
        if (val & STS_COMMAND_READY) {
            if (s->loc[locty].state == STATE_IDLE) {
                s->loc[locty].sts   = STS_COMMAND_READY;
                s->loc[locty].state = STATE_READY;
                tis_raise_irq(s, locty, INT_COMMAND_READY);
            } else if (s->loc[locty].state == STATE_COMPLETION ||
                       s->loc[locty].state == STATE_EXECUTION  ||
                       s->loc[locty].state == STATE_RECEPTION) {
                /* abort currently running command */
                tis_prep_abort(s, locty, locty);
            }
        }
        if (val & STS_TPM_GO) {
            n = TPM_Send(s, &s->buffer, locty, "tpm_data_write");
            if (n > 0) {
                /* sending of data was successful */
                s->offset = 0;
                s->loc[locty].state = STATE_EXECUTION;
                if (s->loc[locty].inte & (INT_ENABLED | INT_DATA_AVAILABLE)) {
                    s->poll_attempts = 0;
                    tis_prep_next_interrupt(s);
                }
            }
        }
        if (val & STS_RESPONSE_RETRY) {
            s->offset = 0;
        }
    } else if (off == TPM_REG_DATA_FIFO) {
        /* data fifo */
        if (s->loc[locty].state == STATE_IDLE ||
            s->loc[locty].state == STATE_EXECUTION ||
            s->loc[locty].state == STATE_COMPLETION) {
            /* drop the byte */
        } else {
#ifdef TPM_DEBUG
        fprintf(logfile,"Byte to send to TPM: %02x\n", val);
#endif
            s->loc[locty].state = STATE_RECEPTION;

            if (s->offset < sizeof(s->buffer.buf))
                s->buffer.buf[s->offset++] = (uint8_t)val;

            if (s->offset > 5) {
                /* we have a packet length - see if we have all of it */
                len = tpm_get_size_from_buffer(s->buffer.buf);
                if (len > s->offset) {
                    s->loc[locty].sts = STS_EXPECT | STS_VALID;
                } else {
                    s->loc[locty].sts = STS_VALID;
                }
            }
        }
    }
}

/*
 * Prepare the next interrupt for example after a command has
 * been sent out for the purpose of receiving the response.
 * Depending on how many interrupts (used for polling on the fd) have
 * already been schedule, this function determines the delta in time
 * to the next interrupt. This accomodates for commands that finish
 * quickly.
 */
static void tis_prep_next_interrupt(tpmState *s)
{
    int64_t expiration;
    int rate = 5; /* 5 times per second */

    /*
       poll often at the beginning for quickly finished commands,
       then back off
     */
    if (s->poll_attempts < 5) {
        rate = 20;
    } else if (s->poll_attempts < 10) {
        rate = 10;
    }

    expiration = qemu_get_clock(vm_clock) + (ticks_per_sec / rate);
    qemu_mod_timer(s->poll_timer, expiration);
    s->poll_attempts++;
}


/*
 * The polling routine called when the 'timer interrupt' fires.
 * Tries to receive a command from the vTPM.
 */
static void tis_poll_timer(void *opaque)
{
    tpmState* s=(tpmState*)opaque;
    uint8_t locty = s->active_loc;

    if (!IS_VALID_LOC(locty) ||
        (!(s->loc[locty].inte & INT_ENABLED) &&
          (s->aborting_locty != NO_LOCALITY)) ||
        !IS_COMM_WITH_VTPM(s)) {
        /* no more interrupts requested, so no more polling needed */
        qemu_del_timer(s->poll_timer);
    }

    if (!IS_COMM_WITH_VTPM(s)) {
        if (s->aborting_locty != NO_LOCALITY) {
            tis_abort(s);
        }
        return;
    }

    if (s->aborting_locty != NO_LOCALITY) {
        int n = TPM_Receive(s, &s->buffer);
#ifdef DEBUG_TPM
        fprintf(logfile,"Receiving for abort.\n");
#endif
        if (n > 0) {
            close_vtpm_channel(s, FORCE_CLOSE);
            tis_abort(s);
#ifdef DEBUG_TPM
            fprintf(logfile,"Abort is complete.\n");
#endif
        } else {
            tis_prep_next_interrupt(s);
        }
    } else if (IS_VALID_LOC(locty)) {
        if (s->loc[locty].state == STATE_EXECUTION) {
           /* poll for result */
            int n = TPM_Receive(s, &s->buffer);
            if (n > 0) {
                s->loc[locty].sts = STS_VALID | STS_DATA_AVAILABLE;
                s->loc[locty].state = STATE_COMPLETION;
                close_vtpm_channel(s, FORCE_CLOSE);
                tis_raise_irq(s, locty, INT_DATA_AVAILABLE);
            } else {
                /* nothing received */
                tis_prep_next_interrupt(s);
            }
        }
    }
}


static CPUReadMemoryFunc *tis_readfn[3]={
    tis_mem_readl,
    tis_mem_readl,
    tis_mem_readl
};

static CPUWriteMemoryFunc *tis_writefn[3]={
    tis_mem_writel,
    tis_mem_writel,
    tis_mem_writel
};

/*
 * Save the internal state of this interface for later resumption.