Re: [PATCH] ppc/spapr: init lrdr-capapcity phys with ram size if maxmem not provided

[Shivaprasad G Bhat <sbhat@linux.ibm.com>]

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