[Bionic][PATCH 08/12] powerpc/pseries/iommu: Use memory@ nodes in max RAM address calculation

[Jose Ricardo Ziviani]

From: Alexey Kardashevskiy <aik at ozlabs.ru>

BugLink: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1819989

We might have memory@ nodes with "linux,usable-memory" set to zero
(for example, to replicate powernv's behaviour for GPU coherent memory)
which means that the memory needs an extra initialization but since
it can be used afterwards, the pseries platform will try mapping it
for DMA so the DMA window needs to cover those memory regions too;
if the window cannot cover new memory regions, the memory onlining fails.

This walks through the memory nodes to find the highest RAM address to
let a huge DMA window cover that too in case this memory gets onlined
later.

Signed-off-by: Alexey Kardashevskiy <aik at ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe at ellerman.id.au>
(cherry picked from commit 68c0449ea16d775e762b532afddb4d6a5f161877)
Signed-off-by: Jose Ricardo Ziviani <joserz at linux.ibm.com>
---
 arch/powerpc/platforms/pseries/iommu.c | 33 +++++++++++++++++++++++++-
 1 file changed, 32 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
index 69921f72e2da..fcb8e7f5736e 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -964,6 +964,37 @@ struct failed_ddw_pdn {
 
 static LIST_HEAD(failed_ddw_pdn_list);
 
+static phys_addr_t ddw_memory_hotplug_max(void)
+{
+	phys_addr_t max_addr = memory_hotplug_max();
+	struct device_node *memory;
+
+	for_each_node_by_type(memory, "memory") {
+		unsigned long start, size;
+		int ranges, n_mem_addr_cells, n_mem_size_cells, len;
+		const __be32 *memcell_buf;
+
+		memcell_buf = of_get_property(memory, "reg", &len);
+		if (!memcell_buf || len <= 0)
+			continue;
+
+		n_mem_addr_cells = of_n_addr_cells(memory);
+		n_mem_size_cells = of_n_size_cells(memory);
+
+		/* ranges in cell */
+		ranges = (len >> 2) / (n_mem_addr_cells + n_mem_size_cells);
+
+		start = of_read_number(memcell_buf, n_mem_addr_cells);
+		memcell_buf += n_mem_addr_cells;
+		size = of_read_number(memcell_buf, n_mem_size_cells);
+		memcell_buf += n_mem_size_cells;
+
+		max_addr = max_t(phys_addr_t, max_addr, start + size);
+	}
+
+	return max_addr;
+}
+
 /*
  * If the PE supports dynamic dma windows, and there is space for a table
  * that can map all pages in a linear offset, then setup such a table,
@@ -1053,7 +1084,7 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
 	}
 	/* verify the window * number of ptes will map the partition */
 	/* check largest block * page size > max memory hotplug addr */
-	max_addr = memory_hotplug_max();
+	max_addr = ddw_memory_hotplug_max();
 	if (query.largest_available_block < (max_addr >> page_shift)) {
 		dev_dbg(&dev->dev, "can't map partition max 0x%llx with %u "
 			  "%llu-sized pages\n", max_addr,  query.largest_available_block,
-- 
2.20.1