lrdr-capacity contains phys field which communicates the maximum address
in bytes and therefore, the most memory that can be allocated to this
partition. This is usually populated when maxmem is provided alongwith
memory size on qemu command line. However since maxmem is an optional
param, this leads to bits being set to 0 in absence of maxmem param.
Fix this by initializing the respective bits as per total mem size in
such case.

Reported-by: Gaurav Batra <gbatra@us.ibm.com>
Tested-by: David Christensen <drc@linux.ibm.com>
Signed-off-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
---
 hw/ppc/spapr.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 702f774cda..9f18642734 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -907,6 +907,7 @@ static void spapr_dt_rtas(SpaprMachineState *spapr, void *fdt)
     int rtas;
     GString *hypertas = g_string_sized_new(256);
     GString *qemu_hypertas = g_string_sized_new(256);
+    uint64_t max_device_addr = 0;
     uint32_t lrdr_capacity[] = {
         0,
         0,
@@ -917,13 +918,15 @@ static void spapr_dt_rtas(SpaprMachineState *spapr, void *fdt)
 
     /* Do we have device memory? */
     if (MACHINE(spapr)->device_memory) {
-        uint64_t max_device_addr = MACHINE(spapr)->device_memory->base +
+        max_device_addr = MACHINE(spapr)->device_memory->base +
             memory_region_size(&MACHINE(spapr)->device_memory->mr);
-
-        lrdr_capacity[0] = cpu_to_be32(max_device_addr >> 32);
-        lrdr_capacity[1] = cpu_to_be32(max_device_addr & 0xffffffff);
+    } else if (ms->ram_size == ms->maxram_size) {
+        max_device_addr = ms->ram_size;
     }
 
+    lrdr_capacity[0] = cpu_to_be32(max_device_addr >> 32);
+    lrdr_capacity[1] = cpu_to_be32(max_device_addr & 0xffffffff);
+
     _FDT(rtas = fdt_add_subnode(fdt, 0, "rtas"));
 
     /* hypertas */
-- 
2.49.0

On 5/6/25 9:59 AM, Harsh Prateek Bora wrote:
> lrdr-capacity contains phys field which communicates the maximum address
> in bytes and therefore, the most memory that can be allocated to this
> partition. This is usually populated when maxmem is provided alongwith
> memory size on qemu command line. However since maxmem is an optional
> param, this leads to bits being set to 0 in absence of maxmem param.
> Fix this by initializing the respective bits as per total mem size in
> such case.
>
> Reported-by: Gaurav Batra <gbatra@us.ibm.com>
> Tested-by: David Christensen <drc@linux.ibm.com>
> Signed-off-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
> ---
>   hw/ppc/spapr.c | 11 +++++++----
>   1 file changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 702f774cda..9f18642734 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -907,6 +907,7 @@ static void spapr_dt_rtas(SpaprMachineState *spapr, void *fdt)
>       int rtas;
>       GString *hypertas = g_string_sized_new(256);
>       GString *qemu_hypertas = g_string_sized_new(256);
> +    uint64_t max_device_addr = 0;
>       uint32_t lrdr_capacity[] = {
>           0,
>           0,
> @@ -917,13 +918,15 @@ static void spapr_dt_rtas(SpaprMachineState *spapr, void *fdt)
>   
>       /* Do we have device memory? */
>       if (MACHINE(spapr)->device_memory) {
> -        uint64_t max_device_addr = MACHINE(spapr)->device_memory->base +
> +        max_device_addr = MACHINE(spapr)->device_memory->base +
>               memory_region_size(&MACHINE(spapr)->device_memory->mr);
> -
> -        lrdr_capacity[0] = cpu_to_be32(max_device_addr >> 32);
> -        lrdr_capacity[1] = cpu_to_be32(max_device_addr & 0xffffffff);
> +    } else if (ms->ram_size == ms->maxram_size) {
> +        max_device_addr = ms->ram_size;
>       }
>   
> +    lrdr_capacity[0] = cpu_to_be32(max_device_addr >> 32);
> +    lrdr_capacity[1] = cpu_to_be32(max_device_addr & 0xffffffff);
> +

Since maxmem accounts for pcdimm and/or nvdimm cases, this would work

fine for all probable scenarios in this code path.


Reviewed-by: Shivaprasad G Bhat <sbhat@linux.ibm.com>


Thanks,

Shivaprasad