tpm: vtpm_proxy: Avoid reading host log when using a virtual device

Avoid allocating memory and reading the host log when a virtual device
is used since this log is of no use to that driver. A virtual
device can be identified through the flag TPM_CHIP_FLAG_VIRTUAL, which
is only set for the tpm_vtpm_proxy driver.

Cc: stable@vger.kernel.org
Fixes: 6f99612e ("tpm: Proxy driver for supporting multiple emulated TPMs")
Signed-off-by: NStefan Berger <stefanb@linux.ibm.com>
Reviewed-by: NJarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: NJarkko Sakkinen <jarkko@kernel.org>

drivers/char/tpm/eventlog/common.c

@@ -107,6 +107,9 @@ void tpm_bios_log_setup(struct tpm_chip *chip)
 	int log_version;
 	int rc = 0;
 
+	if (chip->flags & TPM_CHIP_FLAG_VIRTUAL)
+		return;
+
 	rc = tpm_read_log(chip);
 	if (rc < 0)
 		return;