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bhyve: do not hold CRB mutex when executing TPM commands

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TPM commands can take up to several seconds to execute. If we hold the
CRB mutex while executing the command, MMIO accesses could be blocked
for a long time. Therefore, just copy all required values and work on
the copied values.

Reviewed by:		markj
MFC after:		1 week
Sponsored by:		Beckhoff Automation GmbH & Co. KG
Differential Revision:	https://reviews.freebsd.org/D40724
This commit is contained in:
Corvin Köhne 2023-06-23 08:31:38 +02:00
parent b9b8a4769c
commit f0124ab111
No known key found for this signature in database
GPG Key ID: D854DA56315E026A
1 changed files with 20 additions and 3 deletions
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23
usr.sbin/bhyve/tpm_intf_crb.c
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@ -184,6 +184,13 @@ tpm_crb_thread(void *const arg)
pthread_mutex_lock(&crb->mutex);
for (;;) {
/*
* We're releasing the lock after wake up. Therefore, we have to
* check the closing condition before and after going to sleep.
*/
if (crb->closing)
break;
pthread_cond_wait(&crb->cond, &crb->mutex);
if (crb->closing)
@ -208,6 +215,16 @@ tpm_crb_thread(void *const arg)
break;
}
uint8_t cmd[TPM_CRB_DATA_BUFFER_SIZE];
memcpy(cmd, crb->regs.data_buffer, TPM_CRB_DATA_BUFFER_SIZE);
/*
* A TPM command can take multiple seconds to execute. As we've
* copied all required values and buffers at this point, we can
* release the mutex.
*/
pthread_mutex_unlock(&crb->mutex);
/*
* The command response buffer interface uses a single buffer
* for sending a command to and receiving a response from the
@ -221,10 +238,10 @@ tpm_crb_thread(void *const arg)
* response.
*/
uint8_t rsp[TPM_CRB_DATA_BUFFER_SIZE] = { 0 };
crb->emul->execute_cmd(crb->emul_sc,
&crb->regs.data_buffer[cmd_off], cmd_size, &rsp[rsp_off],
rsp_size);
crb->emul->execute_cmd(crb->emul_sc, &cmd[cmd_off], cmd_size,
&rsp[rsp_off], rsp_size);
pthread_mutex_lock(&crb->mutex);
memset(crb->regs.data_buffer, 0, TPM_CRB_DATA_BUFFER_SIZE);
memcpy(&crb->regs.data_buffer[rsp_off], &rsp[rsp_off], rsp_size);