crypto: qat - test PFVF registers for spurious interrupts on GEN4

Spurious PFVF interrupts can happen when either the ISR is invoked
without a valid source being set or, otherwise, when no interrupt bit
is set in the PFVF register containing the message.

The latter test was present for GEN2 devices but missing for GEN4, this
patch fills the gap.
Signed-off-by: Marco Chiappero <marco.chiappero@intel.com>
Reviewed-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/qat/qat_common/adf_gen4_pfvf.c

@@ -96,10 +96,16 @@ static struct pfvf_message adf_gen4_pfvf_recv(struct adf_accel_dev *accel_dev,
 					      u32 pfvf_offset, u8 compat_ver)
 {
 	void __iomem *pmisc_addr = adf_get_pmisc_base(accel_dev);
+	struct pfvf_message msg = { 0 };
 	u32 csr_val;
 
 	/* Read message from the CSR */
 	csr_val = ADF_CSR_RD(pmisc_addr, pfvf_offset);
+	if (!(csr_val & ADF_PFVF_INT)) {
+		dev_info(&GET_DEV(accel_dev),
+			 "Spurious PFVF interrupt, msg 0x%.8x. Ignored\n", csr_val);
+		return msg;
+	}
 
 	/* We can now acknowledge the message reception by clearing the
 	 * interrupt bit