Re: [PATCH] hmat acpi: Don't require initiator value in -numa when hmat=on

[Jonathan Cameron via <qemu-devel@nongnu.org>]

On Wed, 6 Apr 2022 14:29:56 +0200
Brice Goglin <Brice.Goglin@inria.fr> wrote:

> From: Brice Goglin <Brice.Goglin@inria.fr>
> 
> The "Memory Proximity Domain Attributes" structure of the ACPI HMAT
> has a "Processor Proximity Domain Valid" flag that is currently
> always set because Qemu -numa requires initiator=X when hmat=on.
> 
> Unsetting this flag allows to create more complex memory topologies
> by having multiple best initiators for a single memory target.
> 
> This patch allows -numa with initiator=X when hmat=on by keeping
> the default value MAX_NODES in numa_state->nodes[i].initiator.
> All places reading numa_state->nodes[i].initiator already check
> whether it's different from MAX_NODES before using it. And
> hmat_build_table_structs() already unset the Valid flag when needed.
> 
> Tested with
> qemu-system-x86_64 -accel kvm \
>   -machine pc,hmat=on \
>   -drive if=pflash,format=raw,file=./OVMF.fd \
>   -drive media=disk,format=qcow2,file=efi.qcow2 \
>   -smp 4 \
>   -m 3G \
>   -object memory-backend-ram,size=1G,id=ram0 \
>   -object memory-backend-ram,size=1G,id=ram1 \
>   -object memory-backend-ram,size=1G,id=ram2 \
>   -numa node,nodeid=0,memdev=ram0,cpus=0-1 \
>   -numa node,nodeid=1,memdev=ram1,cpus=2-3 \
>   -numa node,nodeid=2,memdev=ram2 \
>   -numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-latency,latency=10 \
>   -numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-bandwidth,bandwidth=10485760 \
>   -numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-latency,latency=20 \
>   -numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-bandwidth,bandwidth=5242880 \
>   -numa hmat-lb,initiator=0,target=2,hierarchy=memory,data-type=access-latency,latency=30 \
>   -numa hmat-lb,initiator=0,target=2,hierarchy=memory,data-type=access-bandwidth,bandwidth=1048576 \
>   -numa hmat-lb,initiator=1,target=0,hierarchy=memory,data-type=access-latency,latency=20 \
>   -numa hmat-lb,initiator=1,target=0,hierarchy=memory,data-type=access-bandwidth,bandwidth=5242880 \
>   -numa hmat-lb,initiator=1,target=1,hierarchy=memory,data-type=access-latency,latency=10 \
>   -numa hmat-lb,initiator=1,target=1,hierarchy=memory,data-type=access-bandwidth,bandwidth=10485760 \
>   -numa hmat-lb,initiator=1,target=2,hierarchy=memory,data-type=access-latency,latency=30 \
>   -numa hmat-lb,initiator=1,target=2,hierarchy=memory,data-type=access-bandwidth,bandwidth=1048576 \
> 
> This exposes NUMA node2 at same distance from both node0 and node1 as seen in lstopo:
> 
> Machine (2966MB total) + Package P#0
>    NUMANode P#2 (979MB)
>    Group0
>      NUMANode P#0 (980MB)
>      Core P#0 + PU P#0
>      Core P#1 + PU P#1
>    Group0
>      NUMANode P#1 (1007MB)
>      Core P#2 + PU P#2
>      Core P#3 + PU P#3
> 
> Signed-off-by: Brice Goglin <Brice.Goglin@inria.fr>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Useful fix / extension of what can be described.

Thanks,

Jonathan
> ---
>   hw/core/machine.c | 4 +---
>   1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/hw/core/machine.c b/hw/core/machine.c
> index d856485cb4..9884ef7ac6 100644
> --- a/hw/core/machine.c
> +++ b/hw/core/machine.c
> @@ -1012,9 +1012,7 @@ static void numa_validate_initiator(NumaState *numa_state)
>   
>       for (i = 0; i < numa_state->num_nodes; i++) {
>           if (numa_info[i].initiator == MAX_NODES) {
> -            error_report("The initiator of NUMA node %d is missing, use "
> -                         "'-numa node,initiator' option to declare it", i);
> -            exit(1);
> +            continue;
>           }
>   
>           if (!numa_info[numa_info[i].initiator].present) {