Re: [PATCH kernel v3 10/22] powerpc/pseries/iommu: Use memory@ nodes in max RAM address calculation
From: David Gibson <hidden>
Date: 2018-11-16 05:49:06
On Tue, Nov 13, 2018 at 07:28:11PM +1100, Alexey Kardashevskiy wrote:
quoted hunk ↗ jump to hunk
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. 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 <redacted> --- arch/powerpc/platforms/pseries/iommu.c | 43 +++++++++++++++++++++++++- 1 file changed, 42 insertions(+), 1 deletion(-)diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c index 78473ac..f818737 100644 --- a/arch/powerpc/platforms/pseries/iommu.c +++ b/arch/powerpc/platforms/pseries/iommu.c@@ -967,6 +967,47 @@ struct failed_ddw_pdn { static LIST_HEAD(failed_ddw_pdn_list); +static unsigned long read_n_cells(int n, const __be32 **buf) +{ + unsigned long result = 0; + + while (n--) { + result = (result << 32) | of_read_number(*buf, 1); + (*buf)++; + } + return result; +}
Um.. this appears to be re-implementing of_read_number() in terms of of_read_number(). Wat!?
+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);
+
+ /* these are order-sensitive, and modify the buffer pointer */
+ start = read_n_cells(n_mem_addr_cells, &memcell_buf);
+ size = read_n_cells(n_mem_size_cells, &memcell_buf);
+
+ max_addr = max_t(phys_addr_t, max_addr, start + size);
+ }
+
+ return max_addr;
+}Is there really no existing place we keep track of maxmimum possible memory address?
quoted hunk ↗ jump to hunk
/* * 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,@@ -1067,7 +1108,7 @@ 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,
-- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson
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