[PATCH 5.7 079/112] tpm: ibmvtpm: Wait for ready buffer before probing for TPM2 attributes

Greg Kroah-Hartman
2020-07-07T15:25:47Z

From: David Gibson <david@gibson.dropbear.id.au>

[ Upstream commit 72d0556dca39f45eca6c4c085e9eb0fc70aec025 ]

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 <david@gibson.dropbear.id.au>
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 {
--
2.25.1