[PATCH 0/2] Preserve the flags portion on 1:1 dma-ranges mapping

[PATCH 0/2] Preserve the flags portion on 1:1 dma-ranges mapping

[Andrea della Porta]

Empty dma-ranges in DT nodes using 3-cell address spcifier cause the
flag portion to be dropped by of_translate_one(), failing the translation
chain. This patch aims at fixing this issue.

Part of this patchset was originally preparatory for a bigger patchset
(see [1]). It has been split in a standalone one for better management
and because it contains a bugfix which is probably of interest to stable
branch.
I've also added new tests to unittest to prove it.

Many thanks,
Andrea

References:
[1] - https://lore.kernel.org/all/3029857353c9499659369c1540ba887d7860670f.1730123575.git.andrea.porta@suse.com/

Andrea della Porta (2):
  of/unittest: Add empty dma-ranges address translation tests
  of: address: Preserve the flags portion on 1:1 dma-ranges mapping

 drivers/of/address.c                        |  3 +-
 drivers/of/unittest-data/tests-address.dtsi |  2 ++
 drivers/of/unittest.c                       | 39 +++++++++++++++++++++
 3 files changed, 43 insertions(+), 1 deletion(-)

-- 
2.35.3

[PATCH 1/2] of/unittest: Add empty dma-ranges address translation tests

[Andrea della Porta]

Intermediate DT PCI nodes dynamically generated by enabling
CONFIG_PCI_DYNAMIC_OF_NODES have empty dma-ranges property. PCI address
specifiers have 3 cells and when dma-ranges is missing or empty,
of_translate_one() is currently dropping the flag portion of PCI addresses
which are subnodes of the aforementioned ones, failing the translation.
Add new tests covering this case.

With this test, we get 1 new failure which is fixed in subsequent
commit:

FAIL of_unittest_pci_empty_dma_ranges():1245 for_each_of_pci_range wrong CPU addr (ffffffffffffffff) on node /testcase-data/address-tests2/pcie@d1070000/pci@0,0/dev@0,0/local-bus@0

Signed-off-by: Andrea della Porta <andrea.porta@suse.com>
---
 drivers/of/unittest-data/tests-address.dtsi |  2 ++
 drivers/of/unittest.c                       | 39 +++++++++++++++++++++
 2 files changed, 41 insertions(+)

diff --git a/drivers/of/unittest-data/tests-address.dtsi b/drivers/of/unittest-data/tests-address.dtsi
index 3344f15c3755..f02a181bb125 100644
--- a/drivers/of/unittest-data/tests-address.dtsi
+++ b/drivers/of/unittest-data/tests-address.dtsi
@@ -114,6 +114,7 @@ pcie@d1070000 {
 				device_type = "pci";
 				ranges = <0x82000000 0 0xe8000000 0 0xe8000000 0 0x7f00000>,
 					 <0x81000000 0 0x00000000 0 0xefff0000 0 0x0010000>;
+				dma-ranges = <0x43000000 0x10 0x00 0x00 0x00 0x00 0x10000000>;
 				reg = <0x00000000 0xd1070000 0x20000>;
 
 				pci@0,0 {
@@ -142,6 +143,7 @@ local-bus@0 {
 							#size-cells = <0x01>;
 							ranges = <0xa0000000 0 0 0 0x2000000>,
 								 <0xb0000000 1 0 0 0x1000000>;
+							dma-ranges = <0xc0000000 0x43000000 0x10 0x00 0x10000000>;
 
 							dev@e0000000 {
 								reg = <0xa0001000 0x1000>,
diff --git a/drivers/of/unittest.c b/drivers/of/unittest.c
index daf9a2dddd7e..80483e38d7b4 100644
--- a/drivers/of/unittest.c
+++ b/drivers/of/unittest.c
@@ -1213,6 +1213,44 @@ static void __init of_unittest_pci_dma_ranges(void)
 	of_node_put(np);
 }
 
+static void __init of_unittest_pci_empty_dma_ranges(void)
+{
+	struct device_node *np;
+	struct of_pci_range range;
+	struct of_pci_range_parser parser;
+
+	if (!IS_ENABLED(CONFIG_PCI))
+		return;
+
+	np = of_find_node_by_path("/testcase-data/address-tests2/pcie@d1070000/pci@0,0/dev@0,0/local-bus@0");
+	if (!np) {
+		pr_err("missing testcase data\n");
+		return;
+	}
+
+	if (of_pci_dma_range_parser_init(&parser, np)) {
+		pr_err("missing dma-ranges property\n");
+		return;
+	}
+
+	/*
+	 * Get the dma-ranges from the device tree
+	 */
+	for_each_of_pci_range(&parser, &range) {
+		unittest(range.size == 0x10000000,
+			 "for_each_of_pci_range wrong size on node %pOF size=%llx\n",
+			 np, range.size);
+		unittest(range.cpu_addr == 0x00000000,
+			 "for_each_of_pci_range wrong CPU addr (%llx) on node %pOF",
+			 range.cpu_addr, np);
+		unittest(range.pci_addr == 0xc0000000,
+			 "for_each_of_pci_range wrong DMA addr (%llx) on node %pOF",
+			 range.pci_addr, np);
+	}
+
+	of_node_put(np);
+}
+
 static void __init of_unittest_bus_ranges(void)
 {
 	struct device_node *np;
@@ -4272,6 +4310,7 @@ static int __init of_unittest(void)
 	of_unittest_dma_get_max_cpu_address();
 	of_unittest_parse_dma_ranges();
 	of_unittest_pci_dma_ranges();
+	of_unittest_pci_empty_dma_ranges();
 	of_unittest_bus_ranges();
 	of_unittest_bus_3cell_ranges();
 	of_unittest_reg();
-- 
2.35.3

[PATCH 2/2] of: address: Preserve the flags portion on 1:1 dma-ranges mapping

[Andrea della Porta]

A missing or empty dma-ranges in a DT node implies a 1:1 mapping for dma
translations. In this specific case, the current behaviour is to zero out
the entire specifier so that the translation could be carried on as an
offset from zero.  This includes address specifier that has flags (e.g.
PCI ranges).
Once the flags portion has been zeroed, the translation chain is broken
since the mapping functions will check the upcoming address specifier
against mismatching flags, always failing the 1:1 mapping and its entire
purpose of always succeeding.
Set to zero only the address portion while passing the flags through.

Fixes: dbbdee94734b ("of/address: Merge all of the bus translation code")
Cc: stable@vger.kernel.org
Signed-off-by: Andrea della Porta <andrea.porta@suse.com>
Tested-by: Herve Codina <herve.codina@bootlin.com>
---
 drivers/of/address.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/of/address.c b/drivers/of/address.c
index 286f0c161e33..72b6accff21c 100644
--- a/drivers/of/address.c
+++ b/drivers/of/address.c
@@ -455,7 +455,8 @@ static int of_translate_one(struct device_node *parent, struct of_bus *bus,
 	}
 	if (ranges == NULL || rlen == 0) {
 		offset = of_read_number(addr, na);
-		memset(addr, 0, pna * 4);
+		/* copy the address while preserving the flags */
+		memset(addr + pbus->flag_cells, 0, (pna - pbus->flag_cells) * 4);
 		pr_debug("empty ranges; 1:1 translation\n");
 		goto finish;
 	}
-- 
2.35.3

Re: [PATCH 2/2] of: address: Preserve the flags portion on 1:1 dma-ranges mapping

[Bjorn Helgaas]

On Fri, Nov 08, 2024 at 11:39:21AM +0100, Andrea della Porta wrote:
> A missing or empty dma-ranges in a DT node implies a 1:1 mapping for dma
> translations. In this specific case, the current behaviour is to zero out
> the entire specifier so that the translation could be carried on as an
> offset from zero.  This includes address specifier that has flags (e.g.
> PCI ranges).
> Once the flags portion has been zeroed, the translation chain is broken
> since the mapping functions will check the upcoming address specifier
> against mismatching flags, always failing the 1:1 mapping and its entire
> purpose of always succeeding.
> Set to zero only the address portion while passing the flags through.

Add blank lines between paragraphs.

> Fixes: dbbdee94734b ("of/address: Merge all of the bus translation code")
> Cc: stable@vger.kernel.org
> Signed-off-by: Andrea della Porta <andrea.porta@suse.com>
> Tested-by: Herve Codina <herve.codina@bootlin.com>
> ---
>  drivers/of/address.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/of/address.c b/drivers/of/address.c
> index 286f0c161e33..72b6accff21c 100644
> --- a/drivers/of/address.c
> +++ b/drivers/of/address.c
> @@ -455,7 +455,8 @@ static int of_translate_one(struct device_node *parent, struct of_bus *bus,
>  	}
>  	if (ranges == NULL || rlen == 0) {
>  		offset = of_read_number(addr, na);
> -		memset(addr, 0, pna * 4);
> +		/* copy the address while preserving the flags */

Not knowing the surrounding code, it seems strange to say "copy the
address" when the memset() fills with zero and does no copying.

The commit log says "set address to zero, pass flags through," and I
could believe *that* matches the memset().

> +		memset(addr + pbus->flag_cells, 0, (pna - pbus->flag_cells) * 4);
>  		pr_debug("empty ranges; 1:1 translation\n");
>  		goto finish;
>  	}
> -- 
> 2.35.3
> 

Re: [PATCH 2/2] of: address: Preserve the flags portion on 1:1 dma-ranges mapping

[Andrea della Porta]

Hi Bjorn,

On 10:56 Fri 08 Nov     , Bjorn Helgaas wrote:
> On Fri, Nov 08, 2024 at 11:39:21AM +0100, Andrea della Porta wrote:
> > A missing or empty dma-ranges in a DT node implies a 1:1 mapping for dma
> > translations. In this specific case, the current behaviour is to zero out
> > the entire specifier so that the translation could be carried on as an
> > offset from zero.  This includes address specifier that has flags (e.g.
> > PCI ranges).
> > Once the flags portion has been zeroed, the translation chain is broken
> > since the mapping functions will check the upcoming address specifier
> > against mismatching flags, always failing the 1:1 mapping and its entire
> > purpose of always succeeding.
> > Set to zero only the address portion while passing the flags through.
> 
> Add blank lines between paragraphs.

Ack.

> 
> > Fixes: dbbdee94734b ("of/address: Merge all of the bus translation code")
> > Cc: stable@vger.kernel.org
> > Signed-off-by: Andrea della Porta <andrea.porta@suse.com>
> > Tested-by: Herve Codina <herve.codina@bootlin.com>
> > ---
> >  drivers/of/address.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/of/address.c b/drivers/of/address.c
> > index 286f0c161e33..72b6accff21c 100644
> > --- a/drivers/of/address.c
> > +++ b/drivers/of/address.c
> > @@ -455,7 +455,8 @@ static int of_translate_one(struct device_node *parent, struct of_bus *bus,
> >  	}
> >  	if (ranges == NULL || rlen == 0) {
> >  		offset = of_read_number(addr, na);
> > -		memset(addr, 0, pna * 4);
> > +		/* copy the address while preserving the flags */
> 
> Not knowing the surrounding code, it seems strange to say "copy the
> address" when the memset() fills with zero and does no copying.
> 
> The commit log says "set address to zero, pass flags through," and I
> could believe *that* matches the memset().

Ack.

Many thanks,
Andrea

> 
> > +		memset(addr + pbus->flag_cells, 0, (pna - pbus->flag_cells) * 4);
> >  		pr_debug("empty ranges; 1:1 translation\n");
> >  		goto finish;
> >  	}
> > -- 
> > 2.35.3
> >