GNUBoot/coreboot-kgpe-d16
2
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

drivers/spi/tpm: Improve error checking

Browse source 
This adds error checking in paths that previously ignored TPM
communication errors. We hit this case occasionally during "Checking
cr50 for pending updates"; previously we would go down this path and
eventually time out using MAX_STATUS_TIMEOUT, which is 2 minutes.
Now, we detect the failure and return with an error indication instead
of timing out after a long time. The root cause of the communication
error is an open issue.

BUG=b:168090038
TEST=booted on volteer, observed error handling when
	"Checking cr50 for pending updates" fails.

Signed-off-by: Caveh Jalali <caveh@chromium.org>
Change-Id: Ia8a1202000abce1857ee694b06b1478e6b045069
Reviewed-on: https://review.coreboot.org/c/coreboot/+/45232
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Jes Klinke <jbk@chromium.org>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
This commit is contained in:
Caveh Jalali 2020-09-10 01:25:29 -07:00 committed by Patrick Georgi
parent 0f651650f3
commit 8274c2926f
1 changed files with 39 additions and 17 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

56
src/drivers/spi/tpm/tpm.c
View file

@ -348,7 +348,7 @@ static int read_tpm_sts(uint32_t *status)
return tpm2_read_reg(TPM_STS_REG, status, sizeof(*status));
}
static int write_tpm_sts(uint32_t status)
static int __must_check write_tpm_sts(uint32_t status)
{
return tpm2_write_reg(TPM_STS_REG, &status, sizeof(status));
}
@ -688,9 +688,9 @@ union fifo_transfer_buffer {
* Transfer requested number of bytes to or from TPM FIFO, accounting for the
* current burst count value.
*/
static void fifo_transfer(size_t transfer_size,
union fifo_transfer_buffer buffer,
enum fifo_transfer_direction direction)
static int __must_check fifo_transfer(size_t transfer_size,
union fifo_transfer_buffer buffer,
enum fifo_transfer_direction direction)
{
size_t transaction_size;
size_t burst_count;
@ -711,18 +711,23 @@ static void fifo_transfer(size_t transfer_size,
*/
transaction_size = MIN(transaction_size, 64);
if (direction == fifo_receive)
tpm2_read_reg(TPM_DATA_FIFO_REG,
buffer.rx_buffer + handled_so_far,
transaction_size);
else
tpm2_write_reg(TPM_DATA_FIFO_REG,
buffer.tx_buffer + handled_so_far,
transaction_size);
if (direction == fifo_receive) {
if (!tpm2_read_reg(TPM_DATA_FIFO_REG,
buffer.rx_buffer + handled_so_far,
transaction_size))
return 0;
} else {
if (!tpm2_write_reg(TPM_DATA_FIFO_REG,
buffer.tx_buffer + handled_so_far,
transaction_size))
return 0;
}
handled_so_far += transaction_size;
} while (handled_so_far != transfer_size);
return 1;
}
size_t tpm2_process_command(const void *tpm2_command, size_t command_size,
@ -755,7 +760,10 @@ size_t tpm2_process_command(const void *tpm2_command, size_t command_size,
}
/* Let the TPM know that the command is coming. */
write_tpm_sts(TPM_STS_COMMAND_READY);
if (!write_tpm_sts(TPM_STS_COMMAND_READY)) {
printk(BIOS_ERR, "TPM_STS_COMMAND_READY failed\n");
return 0;
}
/*
* TPM commands and responses written to and read from the FIFO
@ -769,10 +777,17 @@ size_t tpm2_process_command(const void *tpm2_command, size_t command_size,
* burst count or the maximum PDU size, whatever is smaller.
*/
fifo_buffer.tx_buffer = cmd_body;
fifo_transfer(command_size, fifo_buffer, fifo_transmit);
if (!fifo_transfer(command_size, fifo_buffer, fifo_transmit)) {
printk(BIOS_ERR, "fifo_transfer %zd command bytes failed\n",
command_size);
return 0;
}
/* Now tell the TPM it can start processing the command. */
write_tpm_sts(TPM_STS_GO);
if (!write_tpm_sts(TPM_STS_GO)) {
printk(BIOS_ERR, "TPM_STS_GO failed\n");
return 0;
}
/* Now wait for it to report that the response is ready. */
expected_status_bits = TPM_STS_VALID | TPM_STS_DATA_AVAIL;
@ -815,7 +830,11 @@ size_t tpm2_process_command(const void *tpm2_command, size_t command_size,
*/
bytes_to_go = payload_size - 1 - HEADER_SIZE;
fifo_buffer.rx_buffer = rsp_body + HEADER_SIZE;
fifo_transfer(bytes_to_go, fifo_buffer, fifo_receive);
if (!fifo_transfer(bytes_to_go, fifo_buffer, fifo_receive)) {
printk(BIOS_ERR, "fifo_transfer %zd receive bytes failed\n",
bytes_to_go);
return 0;
}
/* Verify that there is still data to read. */
read_tpm_sts(&status);
@ -840,7 +859,10 @@ size_t tpm2_process_command(const void *tpm2_command, size_t command_size,
}
/* Move the TPM back to idle state. */
write_tpm_sts(TPM_STS_COMMAND_READY);
if (!write_tpm_sts(TPM_STS_COMMAND_READY)) {
printk(BIOS_ERR, "TPM_STS_COMMAND_READY failed\n");
return 0;
}
return payload_size;
}