Re: [PATCH 09/10] ACPI: IORT: Cast from ULL to phys_addr_t

[Moritz Fischer]

On Tue, Nov 28, 2023 at 08:48:05PM -0400, Jason Gunthorpe wrote:

gcc on i386 (when compile testing) warns:

This is a weird test. The Makefile for drivers/acpi/arm64 is conditional
on CONFIG_ARM64. How does this happen?

8->8

obj-$(CONFIG_ARM64)             += arm64/

8->8

drivers/acpi/arm64/iort.c:2014:18: warning: implicit conversion from 'unsigned long long' to 'phys_addr_t' (aka 'unsigned int') changes value from 18446744073709551615 to 4294967295 [-Wconstant-conversion] local_limit = DMA_BIT_MASK(ncomp->memory_address_limit);

Because DMA_BIT_MASK returns a large ULL constant. Explicitly truncate it
to phys_addr_t.

Signed-off-by: Jason Gunthorpe <j...@nvidia.com>
---
  drivers/acpi/arm64/iort.c | 6 ++++--
  1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
index 6496ff5a6ba20d..bdaf9256870d92 100644
--- a/drivers/acpi/arm64/iort.c
+++ b/drivers/acpi/arm64/iort.c

@@ -2011,7 +2011,8 @@ phys_addr_t __init acpi_iort_dma_get_max_cpu_address(void)

                case ACPI_IORT_NODE_NAMED_COMPONENT:
                        ncomp = (struct acpi_iort_named_component 
*)node->node_data;
-                       local_limit = DMA_BIT_MASK(ncomp->memory_address_limit);
+                       local_limit = (phys_addr_t)DMA_BIT_MASK(
+                               ncomp->memory_address_limit);
                        limit = min_not_zero(limit, local_limit);
                        break;

@@ -2020,7 +2021,8 @@ phys_addr_t __init acpi_iort_dma_get_max_cpu_address(void)

                                break;

                        rc = (struct acpi_iort_root_complex *)node->node_data;
-                       local_limit = DMA_BIT_MASK(rc->memory_address_limit);
+                       local_limit = (phys_addr_t)DMA_BIT_MASK(
+                               rc->memory_address_limit);
                        limit = min_not_zero(limit, local_limit);
                        break;
                }
--
2.42.0

Cheers,
Moritz