crypto: qat - detect PFVF collision after ACK

Detect a PFVF collision between the local and the remote function by
checking if the message on the PFVF CSR has been overwritten.
This is done after the remote function confirms that the message has
been received, by clearing the interrupt bit, or the maximum number of
attempts (ADF_IOV_MSG_ACK_MAX_RETRY) to check the CSR has been exceeded.

Fixes: ed8ccae ("crypto: qat - Add support for SRIOV")
Signed-off-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Co-developed-by: Marco Chiappero <marco.chiappero@intel.com>
Signed-off-by: Marco Chiappero <marco.chiappero@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/qat/qat_common/adf_pf2vf_msg.c

@@ -156,6 +156,13 @@ static int __adf_iov_putmsg(struct adf_accel_dev *accel_dev, u32 msg, u8 vf_nr)
 		val = ADF_CSR_RD(pmisc_bar_addr, pf2vf_offset);
 	} while ((val & int_bit) && (count++ < ADF_IOV_MSG_ACK_MAX_RETRY));
 
+	if (val != msg) {
+		dev_dbg(&GET_DEV(accel_dev),
+			"Collision - PFVF CSR overwritten by remote function\n");
+		ret = -EIO;
+		goto out;
+	}
+
 	if (val & int_bit) {
 		dev_dbg(&GET_DEV(accel_dev), "ACK not received from remote\n");
 		val &= ~int_bit;