[PATCH kernel 0/3] powerpc/pseries/ddw: Fixes for persistent memory case

[PATCH kernel 0/3] powerpc/pseries/ddw: Fixes for persistent memory case

[Alexey Kardashevskiy]

This is based on sha1
f855455dee0b Michael Ellerman "Automatic merge of 'next' into merge (2021-11-05 22:19)".

Please comment. Thanks.



Alexey Kardashevskiy (3):
  powerpc/pseries/ddw: Revert "Extend upper limit for huge DMA window
    for persistent memory"
  powerpc/pseries/ddw: simplify enable_ddw()
  powerpc/pseries/ddw: Do not try direct mapping with persistent memory
    and one window

 arch/powerpc/platforms/pseries/iommu.c | 26 ++++++++------------------
 1 file changed, 8 insertions(+), 18 deletions(-)

-- 
2.30.2

[PATCH kernel 1/3] powerpc/pseries/ddw: Revert "Extend upper limit for huge DMA window for persistent memory"

[Alexey Kardashevskiy]

This reverts commit 54fc3c681ded9437e4548e2501dc1136b23cfa9a
which does not allow 1:1 mapping even for the system RAM which
is usually possible.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
 arch/powerpc/platforms/pseries/iommu.c | 9 ---------
 1 file changed, 9 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
index 49b401536d29..64385d6f33c2 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -1094,15 +1094,6 @@ static phys_addr_t ddw_memory_hotplug_max(void)
 	phys_addr_t max_addr = memory_hotplug_max();
 	struct device_node *memory;
 
-	/*
-	 * The "ibm,pmemory" can appear anywhere in the address space.
-	 * Assuming it is still backed by page structs, set the upper limit
-	 * for the huge DMA window as MAX_PHYSMEM_BITS.
-	 */
-	if (of_find_node_by_type(NULL, "ibm,pmemory"))
-		return (sizeof(phys_addr_t) * 8 <= MAX_PHYSMEM_BITS) ?
-			(phys_addr_t) -1 : (1ULL << MAX_PHYSMEM_BITS);
-
 	for_each_node_by_type(memory, "memory") {
 		unsigned long start, size;
 		int n_mem_addr_cells, n_mem_size_cells, len;
-- 
2.30.2

[PATCH kernel 2/3] powerpc/pseries/ddw: simplify enable_ddw()

[Alexey Kardashevskiy]

This drops rather useless ddw_enabled flag as direct_mapping implies
it anyway.

While at this, fix indents in enable_ddw().

This should not cause any behavioral change.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---

This replaces "powerpc/pseries/iommu: Fix indentations"
---
 arch/powerpc/platforms/pseries/iommu.c | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
index 64385d6f33c2..301fa5b3d528 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -1229,7 +1229,6 @@ static bool enable_ddw(struct pci_dev *dev, struct device_node *pdn)
 	u32 ddw_avail[DDW_APPLICABLE_SIZE];
 	struct dma_win *window;
 	struct property *win64;
-	bool ddw_enabled = false;
 	struct failed_ddw_pdn *fpdn;
 	bool default_win_removed = false, direct_mapping = false;
 	bool pmem_present;
@@ -1244,7 +1243,6 @@ static bool enable_ddw(struct pci_dev *dev, struct device_node *pdn)
 
 	if (find_existing_ddw(pdn, &dev->dev.archdata.dma_offset, &len)) {
 		direct_mapping = (len >= max_ram_len);
-		ddw_enabled = true;
 		goto out_unlock;
 	}
 
@@ -1397,8 +1395,8 @@ static bool enable_ddw(struct pci_dev *dev, struct device_node *pdn)
 			dev_info(&dev->dev, "failed to map DMA window for %pOF: %d\n",
 				 dn, ret);
 
-		/* Make sure to clean DDW if any TCE was set*/
-		clean_dma_window(pdn, win64->value);
+			/* Make sure to clean DDW if any TCE was set*/
+			clean_dma_window(pdn, win64->value);
 			goto out_del_list;
 		}
 	} else {
@@ -1445,7 +1443,6 @@ static bool enable_ddw(struct pci_dev *dev, struct device_node *pdn)
 	spin_unlock(&dma_win_list_lock);
 
 	dev->dev.archdata.dma_offset = win_addr;
-	ddw_enabled = true;
 	goto out_unlock;
 
 out_del_list:
@@ -1481,10 +1478,10 @@ static bool enable_ddw(struct pci_dev *dev, struct device_node *pdn)
 	 * as RAM, then we failed to create a window to cover persistent
 	 * memory and need to set the DMA limit.
 	 */
-	if (pmem_present && ddw_enabled && direct_mapping && len == max_ram_len)
+	if (pmem_present && direct_mapping && len == max_ram_len)
 		dev->dev.bus_dma_limit = dev->dev.archdata.dma_offset + (1ULL << len);
 
-    return ddw_enabled && direct_mapping;
+	return direct_mapping;
 }
 
 static void pci_dma_dev_setup_pSeriesLP(struct pci_dev *dev)
-- 
2.30.2

[PATCH kernel 3/3] powerpc/pseries/ddw: Do not try direct mapping with persistent memory and one window

[Alexey Kardashevskiy]

There is a possibility of having just one DMA window available with
a limited capacity which the existing code does not handle that well.
If the window is big enough for the system RAM but less than
MAX_PHYSMEM_BITS (which we want when persistent memory is present),
we create 1:1 window and leave persistent memory without DMA.

This disables 1:1 mapping entirely if there is persistent memory and
either:
- the huge DMA window does not cover the entire address space;
- the default DMA window is removed.

This relies on reverted 54fc3c681ded
("powerpc/pseries/ddw: Extend upper limit for huge DMA window for persistent memory")
to return the actual amount RAM in ddw_memory_hotplug_max() (posted
separately).

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
 arch/powerpc/platforms/pseries/iommu.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
index 301fa5b3d528..8f998e55735b 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -1356,8 +1356,10 @@ static bool enable_ddw(struct pci_dev *dev, struct device_node *pdn)
 		len = order_base_2(query.largest_available_block << page_shift);
 		win_name = DMA64_PROPNAME;
 	} else {
-		direct_mapping = true;
-		win_name = DIRECT64_PROPNAME;
+		direct_mapping = !default_win_removed ||
+			(len == MAX_PHYSMEM_BITS) ||
+			(!pmem_present && (len == max_ram_len));
+		win_name = direct_mapping ? DIRECT64_PROPNAME : DMA64_PROPNAME;
 	}
 
 	ret = create_ddw(dev, ddw_avail, &create, page_shift, len);
-- 
2.30.2

Re: [PATCH kernel 0/3] powerpc/pseries/ddw: Fixes for persistent memory case

[Michael Ellerman]

On Mon, 8 Nov 2021 15:03:16 +1100, Alexey Kardashevskiy wrote:
> This is based on sha1
> f855455dee0b Michael Ellerman "Automatic merge of 'next' into merge (2021-11-05 22:19)".
> 
> Please comment. Thanks.
> 
> 
> 
> [...]

Applied to powerpc/fixes.

[1/3] powerpc/pseries/ddw: Revert "Extend upper limit for huge DMA window for persistent memory"
      https://git.kernel.org/powerpc/c/2d33f5504490a9d90924476dbccd4a5349ee1ad0
[2/3] powerpc/pseries/ddw: simplify enable_ddw()
      https://git.kernel.org/powerpc/c/fb4ee2b30cd09e95524640149e4ee0d7f22c3e7b
[3/3] powerpc/pseries/ddw: Do not try direct mapping with persistent memory and one window
      https://git.kernel.org/powerpc/c/ad3976025b311cdeb822ad3e7a7554018cb0f83f

cheers