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_common/adf_accel_devices.h b/drivers/crypto/qat/qat_common/adf_accel_devices.h
index 180c7dba3ff2..8250cf856e07 100644
--- a/drivers/crypto/qat/qat_common/adf_accel_devices.h
+++ b/drivers/crypto/qat/qat_common/adf_accel_devices.h
@@ -246,6 +246,8 @@ struct adf_accel_dev {
 	struct adf_accel_pci accel_pci_dev;
 	union {
 		struct {
+			/* protects VF2PF interrupts access */
+			spinlock_t vf2pf_ints_lock;
 			/* vf_info is non-zero when SR-IOV is init'ed */
 			struct adf_accel_vf_info *vf_info;
 		} pf;