[PATCH kernel v4 02/10] powerpc/powernv/iommu: Add real mode version of iommu_table_ops::exchange()

Alexey Kardashevskiy
2017-02-07T07:17:30Z

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>
---
arch/powerpc/include/asm/iommu.h | 7 +++++++
arch/powerpc/kernel/iommu.c | 23 +++++++++++++++++++++++
arch/powerpc/platforms/powernv/pci-ioda.c | 26 +++++++++++++++++++++++++-
3 files changed, 55 insertions(+), 1 deletion(-)

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,
diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c
index 5f202a566ec5..9bace5df05d5 100644
--- a/arch/powerpc/kernel/iommu.c
+++ b/arch/powerpc/kernel/iommu.c
@@ -1004,6 +1004,29 @@ long iommu_tce_xchg(struct iommu_table *tbl, unsigned long entry,
}
EXPORT_SYMBOL_GPL(iommu_tce_xchg);

+long iommu_tce_xchg_rm(struct iommu_table *tbl, unsigned long entry,
+ unsigned long *hpa, enum dma_data_direction *direction)
+{
+ long ret;
+
+ ret = tbl->it_ops->exchange_rm(tbl, entry, hpa, direction);
+
+ if (!ret && ((*direction == DMA_FROM_DEVICE) ||
+ (*direction == DMA_BIDIRECTIONAL))) {
+ struct page *pg = realmode_pfn_to_page(*hpa >> PAGE_SHIFT);
+
+ if (likely(pg)) {
+ SetPageDirty(pg);
+ } else {
+ tbl->it_ops->exchange_rm(tbl, entry, hpa, direction);
+ ret = -EFAULT;
+ }
+ }
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(iommu_tce_xchg_rm);
+
int iommu_take_ownership(struct iommu_table *tbl)
{
unsigned long flags, i, sz = (tbl->it_size + 7) >> 3;
diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
index 5fcae29107e1..1c2826fa812e 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -1856,6 +1856,17 @@ static int pnv_ioda1_tce_xchg(struct iommu_table *tbl, long index,

return ret;
}
+
+static int pnv_ioda1_tce_xchg_rm(struct iommu_table *tbl, long index,
+ unsigned long *hpa, enum dma_data_direction *direction)
+{
+ long ret = pnv_tce_xchg(tbl, index, hpa, direction);
+
+ if (!ret)
+ pnv_pci_p7ioc_tce_invalidate(tbl, index, 1, true);
+
+ return ret;
+}
#endif

static void pnv_ioda1_tce_free(struct iommu_table *tbl, long index,
@@ -1870,6 +1881,7 @@ static struct iommu_table_ops pnv_ioda1_iommu_ops = {
.set = pnv_ioda1_tce_build,
#ifdef CONFIG_IOMMU_API
.exchange = pnv_ioda1_tce_xchg,
+ .exchange_rm = pnv_ioda1_tce_xchg_rm,
#endif
.clear = pnv_ioda1_tce_free,
.get = pnv_tce_get,
@@ -1944,7 +1956,7 @@ static void pnv_pci_ioda2_tce_invalidate(struct iommu_table *tbl,
{
struct iommu_table_group_link *tgl;

- list_for_each_entry_rcu(tgl, &tbl->it_group_list, next) {
+ list_for_each_entry_lockless(tgl, &tbl->it_group_list, next) {
struct pnv_ioda_pe *pe = container_of(tgl->table_group,
struct pnv_ioda_pe, table_group);
struct pnv_phb *phb = pe->phb;
@@ -2000,6 +2012,17 @@ static int pnv_ioda2_tce_xchg(struct iommu_table *tbl, long index,

return ret;
}
+
+static int pnv_ioda2_tce_xchg_rm(struct iommu_table *tbl, long index,
+ unsigned long *hpa, enum dma_data_direction *direction)
+{
+ long ret = pnv_tce_xchg(tbl, index, hpa, direction);
+
+ if (!ret)
+ pnv_pci_ioda2_tce_invalidate(tbl, index, 1, true);
+
+ return ret;
+}
#endif

static void pnv_ioda2_tce_free(struct iommu_table *tbl, long index,
@@ -2020,6 +2043,7 @@ static struct iommu_table_ops pnv_ioda2_iommu_ops = {
.set = pnv_ioda2_tce_build,
#ifdef CONFIG_IOMMU_API
.exchange = pnv_ioda2_tce_xchg,
+ .exchange_rm = pnv_ioda2_tce_xchg_rm,
#endif
.clear = pnv_ioda2_tce_free,
.get = pnv_tce_get,
--
2.11.0