crypto: qat - rework the VF2PF interrupt handling logic

Change the VF2PF interrupt handler in the PF ISR and the definition of
the internal PFVF API to correct the current implementation, which can
result in missed interrupts.

More specifically, current HW generations consider a write to the mask
register, regardless of the value, as an acknowledge of any pending
VF2PF interrupt. Therefore, if there is an interrupt between the source
register read and the mask register write, such interrupt will not be
delivered and silently acknowledged, resulting in a lost VF2PF message.

To work around the problem, rather than disabling specific interrupts,
disable all the interrupts and re-enable only the ones that we are not
serving (excluding the already disabled ones too). This will force any
other pending interrupt to be triggered and be serviced by a subsequent
ISR.

This new approach requires, however, changes to the interrupt related
pfvf_ops functions. In particular, get_vf2pf_sources() has now been
removed in favor of disable_pending_vf2pf_interrupts(), which not only
retrieves and returns the pending (and enabled) sources, but also
disables them.
As a consequence, introduce the adf_disable_pending_vf2pf_interrupts()
utility in place of adf_disable_vf2pf_interrupts_irq(), which is no
longer needed.

Cc: stable@vger.kernel.org
Fixes: 993161d ("crypto: qat - fix handling of VF to PF interrupts")
Signed-off-by: Marco Chiappero <marco.chiappero@intel.com>
Co-developed-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Signed-off-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 7 insertions, 10 deletions

diff --git a/drivers/crypto/qat/qat_common/adf_isr.c b/drivers/crypto/qat/qat_common/adf_isr.c
index a35149f8bf1e..23f7fff32c64 100644
--- a/drivers/crypto/qat/qat_common/adf_isr.c
+++ b/drivers/crypto/qat/qat_common/adf_isr.c
@@ -76,32 +76,29 @@ void adf_disable_vf2pf_interrupts(struct adf_accel_dev *accel_dev, u32 vf_mask)
 	spin_unlock_irqrestore(&accel_dev->pf.vf2pf_ints_lock, flags);
 }
 
-static void adf_disable_vf2pf_interrupts_irq(struct adf_accel_dev *accel_dev,
-					     u32 vf_mask)
+static u32 adf_disable_pending_vf2pf_interrupts(struct adf_accel_dev *accel_dev)
 {
 	void __iomem *pmisc_addr = adf_get_pmisc_base(accel_dev);
+	u32 pending;
 
 	spin_lock(&accel_dev->pf.vf2pf_ints_lock);
-	GET_PFVF_OPS(accel_dev)->disable_vf2pf_interrupts(pmisc_addr, vf_mask);
+	pending = GET_PFVF_OPS(accel_dev)->disable_pending_vf2pf_interrupts(pmisc_addr);
 	spin_unlock(&accel_dev->pf.vf2pf_ints_lock);
+
+	return pending;
 }
 
 static bool adf_handle_vf2pf_int(struct adf_accel_dev *accel_dev)
 {
-	void __iomem *pmisc_addr = adf_get_pmisc_base(accel_dev);
 	bool irq_handled = false;
 	unsigned long vf_mask;
 
-	/* Get the interrupt sources triggered by VFs */
-	vf_mask = GET_PFVF_OPS(accel_dev)->get_vf2pf_sources(pmisc_addr);
-
+	/* Get the interrupt sources triggered by VFs, except for those already disabled */
+	vf_mask = adf_disable_pending_vf2pf_interrupts(accel_dev);
 	if (vf_mask) {
 		struct adf_accel_vf_info *vf_info;
 		int i;
 
-		/* Disable VF2PF interrupts for VFs with pending ints */
-		adf_disable_vf2pf_interrupts_irq(accel_dev, vf_mask);
-
 		/*
 		 * Handle VF2PF interrupt unless the VF is malicious and
 		 * is attempting to flood the host OS with VF2PF interrupts.