powerpc/powernv/iommu: Add real mode version of iommu_table_ops::exchange()

In real mode, TCE tables are invalidated using special
cache-inhibited store instructions which are not available in
virtual mode

This defines and implements exchange_rm() callback. This does not
define set_rm/clear_rm/flush_rm callbacks as there is no user for those -
exchange/exchange_rm are only to be used by KVM for VFIO.

The exchange_rm callback is defined for IODA1/IODA2 powernv platforms.

This replaces list_for_each_entry_rcu with its lockless version as
from now on pnv_pci_ioda2_tce_invalidate() can be called in
the real mode too.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 7 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/iommu.h b/arch/powerpc/include/asm/iommu.h
index 2c1d50792944..4554699aec02 100644
--- a/arch/powerpc/include/asm/iommu.h
+++ b/arch/powerpc/include/asm/iommu.h
@@ -64,6 +64,11 @@ struct iommu_table_ops {
                         long index,
                         unsigned long *hpa,
                         enum dma_data_direction *direction);
+        /* Real mode */
+        int (*exchange_rm)(struct iommu_table *tbl,
+                        long index,
+                        unsigned long *hpa,
+                        enum dma_data_direction *direction);
 #endif
         void (*clear)(struct iommu_table *tbl,
                         long index, long npages);
@@ -208,6 +213,8 @@ extern void iommu_del_device(struct device *dev);
 extern int __init tce_iommu_bus_notifier_init(void);
 extern long iommu_tce_xchg(struct iommu_table *tbl, unsigned long entry,
                 unsigned long *hpa, enum dma_data_direction *direction);
+extern long iommu_tce_xchg_rm(struct iommu_table *tbl, unsigned long entry,
+                unsigned long *hpa, enum dma_data_direction *direction);
 #else
 static inline void iommu_register_group(struct iommu_table_group *table_group,
                                         int pci_domain_number,