iommu_mem_notifier() is invoked when RAM is dynamically
added/removed. This
notifier call is responsible to add/remove TCEs from the Dynamic DMA
Window
(DDW) when TCEs are pre-mapped. TCEs are pre-mapped only for RAM and not
for persistent memory (pmemory). For DMA buffers in pmemory, TCEs are
dynamically mapped when the device driver instructs to do so.
The issue is 'daxctl' command is capable of adding pmemory as "System
RAM"
after LPAR boot. The command to do so is -
daxctl reconfigure-device --mode=system-ram dax0.0 --force
This will dynamically add pmemory range to LPAR RAM eventually invoking
iommu_mem_notifier(). The address range of pmemory is way beyond the Max
RAM that the LPAR can have. Which means, this range is beyond the DDW
created for the device, at device initialization time.
As a result when TCEs are pre-mapped for the pmemory range, by
iommu_mem_notifier(), PHYP HCALL returns H_PARAMETER. This failed the
command, daxctl, to add pmemory as RAM.
The solution is to not pre-map TCEs for pmemory.
Signed-off-by: Gaurav Batra <gba...@linux.ibm.com>
---
arch/powerpc/include/asm/mmzone.h | 1 +
arch/powerpc/mm/numa.c | 2 +-
arch/powerpc/platforms/pseries/iommu.c | 29 ++++++++++++++------------
3 files changed, 18 insertions(+), 14 deletions(-)
diff --git a/arch/powerpc/include/asm/mmzone.h
b/arch/powerpc/include/asm/mmzone.h
index d99863cd6cde..049152f8d597 100644
--- a/arch/powerpc/include/asm/mmzone.h
+++ b/arch/powerpc/include/asm/mmzone.h
@@ -29,6 +29,7 @@ extern cpumask_var_t node_to_cpumask_map[];
#ifdef CONFIG_MEMORY_HOTPLUG
extern unsigned long max_pfn;
u64 memory_hotplug_max(void);
+u64 hot_add_drconf_memory_max(void);
#else
#define memory_hotplug_max() memblock_end_of_DRAM()
#endif
diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index 3c1da08304d0..603a0f652ba6 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -1336,7 +1336,7 @@ int hot_add_scn_to_nid(unsigned long scn_addr)
return nid;
}
-static u64 hot_add_drconf_memory_max(void)
+u64 hot_add_drconf_memory_max(void)
{
struct device_node *memory = NULL;
struct device_node *dn = NULL;
diff --git a/arch/powerpc/platforms/pseries/iommu.c
b/arch/powerpc/platforms/pseries/iommu.c
index 29f1a0cc59cd..abd9529a8f41 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -1284,17 +1284,13 @@ static LIST_HEAD(failed_ddw_pdn_list);
static phys_addr_t ddw_memory_hotplug_max(void)
{
- resource_size_t max_addr = memory_hotplug_max();
- struct device_node *memory;
+ resource_size_t max_addr;
- for_each_node_by_type(memory, "memory") {
- struct resource res;
-
- if (of_address_to_resource(memory, 0, &res))
- continue;
-
- max_addr = max_t(resource_size_t, max_addr, res.end + 1);
- }
+#if defined(CONFIG_NUMA) && defined(CONFIG_MEMORY_HOTPLUG)
+ max_addr = hot_add_drconf_memory_max();
+#else
+ max_addr = memblock_end_of_DRAM();
+#endif
return max_addr;
}
@@ -1600,7 +1596,7 @@ static bool enable_ddw(struct pci_dev *dev,
struct device_node *pdn)
if (direct_mapping) {
/* DDW maps the whole partition, so enable direct DMA
mapping */
- ret = walk_system_ram_range(0, memblock_end_of_DRAM() >>
PAGE_SHIFT,
+ ret = walk_system_ram_range(0, ddw_memory_hotplug_max() >>
PAGE_SHIFT,
win64->value,
tce_setrange_multi_pSeriesLP_walk);
if (ret) {
dev_info(&dev->dev, "failed to map DMA window for %pOF:
%d\n",
@@ -2346,11 +2342,17 @@ static int iommu_mem_notifier(struct
notifier_block *nb, unsigned long action,
struct memory_notify *arg = data;
int ret = 0;
+ /* This notifier can get called when onlining persistent
memory as well.
+ * TCEs are not pre-mapped for persistent memory. Persistent
memory will
+ * always be above ddw_memory_hotplug_max()
+ */
+
switch (action) {
case MEM_GOING_ONLINE:
spin_lock(&dma_win_list_lock);
list_for_each_entry(window, &dma_win_list, list) {
- if (window->direct) {
+ if (window->direct && (arg->start_pfn << PAGE_SHIFT) <
+ ddw_memory_hotplug_max()) {
