Re: [PATCHv2] tpm: ibmvtpm: Wait for ready buffer before probing for TPM2 attributes
From: Jerry Snitselaar <hidden>
Date: 2020-06-19 03:42:51
Also in:
linux-integrity, lkml
On Fri Jun 19 20, David Gibson wrote:
The tpm2_get_cc_attrs_tbl() call will result in TPM commands being issued,
which will need the use of the internal command/response buffer. But,
we're issuing this *before* we've waited to make sure that buffer is
allocated.
This can result in intermittent failures to probe if the hypervisor / TPM
implementation doesn't respond quickly enough. I find it fails almost
every time with an 8 vcpu guest under KVM with software emulated TPM.
To fix it, just move the tpm2_get_cc_attrs_tlb() call after the
existing code to wait for initialization, which will ensure the buffer
is allocated.
Fixes: 18b3670d79ae9 ("tpm: ibmvtpm: Add support for TPM2")
Signed-off-by: David Gibson <redacted>
---Reviewed-by: Jerry Snitselaar <redacted>
quoted hunk ↗ jump to hunk
Changes from v1: * Fixed a formatting error in the commit message * Added some more detail to the commit message drivers/char/tpm/tpm_ibmvtpm.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-)diff --git a/drivers/char/tpm/tpm_ibmvtpm.c b/drivers/char/tpm/tpm_ibmvtpm.c index 09fe45246b8cc..994385bf37c0c 100644 --- a/drivers/char/tpm/tpm_ibmvtpm.c +++ b/drivers/char/tpm/tpm_ibmvtpm.c@@ -683,13 +683,6 @@ static int tpm_ibmvtpm_probe(struct vio_dev *vio_dev,if (rc) goto init_irq_cleanup; - if (!strcmp(id->compat, "IBM,vtpm20")) { - chip->flags |= TPM_CHIP_FLAG_TPM2; - rc = tpm2_get_cc_attrs_tbl(chip); - if (rc) - goto init_irq_cleanup; - } - if (!wait_event_timeout(ibmvtpm->crq_queue.wq, ibmvtpm->rtce_buf != NULL, HZ)) {@@ -697,6 +690,13 @@ static int tpm_ibmvtpm_probe(struct vio_dev *vio_dev,goto init_irq_cleanup; } + if (!strcmp(id->compat, "IBM,vtpm20")) { + chip->flags |= TPM_CHIP_FLAG_TPM2; + rc = tpm2_get_cc_attrs_tbl(chip); + if (rc) + goto init_irq_cleanup; + } + return tpm_chip_register(chip); init_irq_cleanup: do { -- 2.26.2