crypto: qat - protect interrupt mask CSRs with a spinlock

In the PF interrupt handler, the interrupt is disabled for a set of VFs
by writing to the interrupt source mask register, ERRMSK.
The interrupt is re-enabled in the bottom half handler by writing to the
same CSR. This is done through the functions enable_vf2pf_interrupts()
and disable_vf2pf_interrupts() which perform a read-modify-write
operation on the ERRMSK registers to mask and unmask the source of
interrupt.

There can be a race condition where the top half handler for one VF
interrupt runs just as the bottom half for another VF is about to
re-enable the interrupt. Depending on whether the top or bottom half
updates the CSR first, this would result either in a spurious interrupt
or in the interrupt not being re-enabled.

This patch protects the access of ERRMSK with a spinlock.

The functions adf_enable_vf2pf_interrupts() and
adf_disable_vf2pf_interrupts() have been changed to acquire a spin lock
before accessing and modifying the ERRMSK registers. These functions use
spin_lock_irqsave() to disable IRQs and avoid potential deadlocks.
In addition, the function adf_disable_vf2pf_interrupts_irq() has been
added. This uses spin_lock() and it is meant to be used in the top half
only.

Signed-off-by: Kanchana Velusamy <kanchanax.velusamy@intel.com>
Co-developed-by: Marco Chiappero <marco.chiappero@intel.com>
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>
Reviewed-by: Fiona Trahe <fiona.trahe@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/crypto/qat/qat_dh895xcc/adf_dh895xcc_hw_data.c b/drivers/crypto/qat/qat_dh895xcc/adf_dh895xcc_hw_data.c
index dced2426edc1..07e7ba5c057d 100644
--- a/drivers/crypto/qat/qat_dh895xcc/adf_dh895xcc_hw_data.c
+++ b/drivers/crypto/qat/qat_dh895xcc/adf_dh895xcc_hw_data.c
@@ -182,6 +182,8 @@ static void adf_enable_ints(struct adf_accel_dev *accel_dev)
 
 static int adf_pf_enable_vf2pf_comms(struct adf_accel_dev *accel_dev)
 {
+	spin_lock_init(&accel_dev->pf.vf2pf_ints_lock);
+
 	return 0;
 }