crypto: qat - prevent spurious MSI interrupt in VF

QAT GEN2 devices suffer from a defect where the MSI interrupt can be
sent multiple times.

If the second (spurious) interrupt is handled before the bottom half
handler runs, then the extra interrupt is effectively ignored because
the bottom half is only scheduled once.
However, if the top half runs again after the bottom half runs, this
will appear as a spurious PF to VF interrupt.

This can be avoided by checking the interrupt mask register in addition
to the interrupt source register in the interrupt handler.

This patch is based on earlier work done by Conor McLoughlin.

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>
Reviewed-by: Fiona Trahe <fiona.trahe@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/drivers/crypto/qat/qat_common/adf_vf_isr.c b/drivers/crypto/qat/qat_common/adf_vf_isr.c
index 3e4f64d248f9bdb6524d99b49e8396c63b2ec862..4359ca633ea9cab74f29bd183eb9d7015cee2439 100644 (file)
--- a/drivers/crypto/qat/qat_common/adf_vf_isr.c
+++ b/drivers/crypto/qat/qat_common/adf_vf_isr.c
@@ -18,6 +18,7 @@
 #include "adf_pf2vf_msg.h"
 
 #define ADF_VINTSOU_OFFSET     0x204
+#define ADF_VINTMSK_OFFSET     0x208
 #define ADF_VINTSOU_BUN                BIT(0)
 #define ADF_VINTSOU_PF2VF      BIT(1)
 
@@ -161,11 +162,20 @@ static irqreturn_t adf_isr(int irq, void *privdata)
                        &GET_BARS(accel_dev)[hw_data->get_misc_bar_id(hw_data)];
        void __iomem *pmisc_bar_addr = pmisc->virt_addr;
        bool handled = false;
-       u32 v_int;
+       u32 v_int, v_mask;
 
        /* Read VF INT source CSR to determine the source of VF interrupt */
        v_int = ADF_CSR_RD(pmisc_bar_addr, ADF_VINTSOU_OFFSET);
 
+       /* Read VF INT mask CSR to determine which sources are masked */
+       v_mask = ADF_CSR_RD(pmisc_bar_addr, ADF_VINTMSK_OFFSET);
+
+       /*
+        * Recompute v_int ignoring sources that are masked. This is to
+        * avoid rescheduling the tasklet for interrupts already handled
+        */
+       v_int &= ~v_mask;
+
        /* Check for PF2VF interrupt */
        if (v_int & ADF_VINTSOU_PF2VF) {
                /* Disable PF to VF interrupt */