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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Stefan Berger <stefanb@linux.ibm.com>,
        Nayna Jain <nayna@linux.ibm.com>,
        Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.4 43/85] tpm: ibmvtpm: Wait for buffer to be set before proceeding
Date:   Tue, 29 Sep 2020 13:00:10 +0200
Message-Id: <20200929105930.386267897@linuxfoundation.org>
In-Reply-To: <20200929105928.198942536@linuxfoundation.org>
References: <20200929105928.198942536@linuxfoundation.org>
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From: Stefan Berger <stefanb@linux.ibm.com>

[ Upstream commit d8d74ea3c00214aee1e1826ca18e77944812b9b4 ]

Synchronize with the results from the CRQs before continuing with
the initialization. This avoids trying to send TPM commands while
the rtce buffer has not been allocated, yet.

This patch fixes an existing race condition that may occurr if the
hypervisor does not quickly respond to the VTPM_GET_RTCE_BUFFER_SIZE
request sent during initialization and therefore the ibmvtpm->rtce_buf
has not been allocated at the time the first TPM command is sent.

Fixes: 132f76294744 ("drivers/char/tpm: Add new device driver to support IBM vTPM")
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Acked-by: Nayna Jain <nayna@linux.ibm.com>
Tested-by: Nayna Jain <nayna@linux.ibm.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 | 9 +++++++++
 drivers/char/tpm/tpm_ibmvtpm.h | 1 +
 2 files changed, 10 insertions(+)

diff --git a/drivers/char/tpm/tpm_ibmvtpm.c b/drivers/char/tpm/tpm_ibmvtpm.c
index 3e6a22658b63b..d4cc1a1ac1f73 100644
--- a/drivers/char/tpm/tpm_ibmvtpm.c
+++ b/drivers/char/tpm/tpm_ibmvtpm.c
@@ -543,6 +543,7 @@ static irqreturn_t ibmvtpm_interrupt(int irq, void *vtpm_instance)
 	 */
 	while ((crq = ibmvtpm_crq_get_next(ibmvtpm)) != NULL) {
 		ibmvtpm_crq_process(crq, ibmvtpm);
+		wake_up_interruptible(&ibmvtpm->crq_queue.wq);
 		crq->valid = 0;
 		smp_wmb();
 	}
@@ -589,6 +590,7 @@ static int tpm_ibmvtpm_probe(struct vio_dev *vio_dev,
 	}
 
 	crq_q->num_entry = CRQ_RES_BUF_SIZE / sizeof(*crq_q->crq_addr);
+	init_waitqueue_head(&crq_q->wq);
 	ibmvtpm->crq_dma_handle = dma_map_single(dev, crq_q->crq_addr,
 						 CRQ_RES_BUF_SIZE,
 						 DMA_BIDIRECTIONAL);
@@ -641,6 +643,13 @@ static int tpm_ibmvtpm_probe(struct vio_dev *vio_dev,
 	if (rc)
 		goto init_irq_cleanup;
 
+	if (!wait_event_timeout(ibmvtpm->crq_queue.wq,
+				ibmvtpm->rtce_buf != NULL,
+				HZ)) {
+		dev_err(dev, "CRQ response timed out\n");
+		goto init_irq_cleanup;
+	}
+
 	return tpm_chip_register(chip);
 init_irq_cleanup:
 	do {
diff --git a/drivers/char/tpm/tpm_ibmvtpm.h b/drivers/char/tpm/tpm_ibmvtpm.h
index 6af92890518f8..1a8c3b698f104 100644
--- a/drivers/char/tpm/tpm_ibmvtpm.h
+++ b/drivers/char/tpm/tpm_ibmvtpm.h
@@ -31,6 +31,7 @@ struct ibmvtpm_crq_queue {
 	struct ibmvtpm_crq *crq_addr;
 	u32 index;
 	u32 num_entry;
+	wait_queue_head_t wq;
 };
 
 struct ibmvtpm_dev {
-- 
2.25.1