[Qemu-devel] [PATCH] spapr: add ibm, chip-id property in device tree

[Qemu-devel] [PATCH] spapr: add ibm, chip-id property in device tree

[Alexey Kardashevskiy]

This adds a "ibm,chip-id" property for CPU nodes which should be the same
for all cores in the same CPU socket. The recent guest kernels use this
information to associate threads with sockets.

Refer to the kernel commit 256f2d4b463d3030ebc8d2b54f427543814a2bdc
for more details.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
 hw/ppc/spapr.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index bf46c38..6366230 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -308,6 +308,8 @@ static void *spapr_create_fdt_skel(hwaddr initrd_base,
     uint32_t interrupt_server_ranges_prop[] = {0, cpu_to_be32(smp_cpus)};
     int i, smt = kvmppc_smt_threads();
     unsigned char vec5[] = {0x0, 0x0, 0x0, 0x0, 0x0, 0x80};
+    QemuOpts *opts = qemu_opts_find(qemu_find_opts("smp-opts"), NULL);
+    unsigned sockets = opts ? qemu_opt_get_number(opts, "sockets", 0) : 0;
 
     fdt = g_malloc0(FDT_MAX_SIZE);
     _FDT((fdt_create(fdt, FDT_MAX_SIZE)));
@@ -465,6 +467,13 @@ static void *spapr_create_fdt_skel(hwaddr initrd_base,
                                page_sizes_prop, page_sizes_prop_size)));
         }
 
+        if (sockets) {
+            int cpus_per_socket = smp_cpus / sockets;
+            uint32_t chip_id = cs->cpu_index / cpus_per_socket;
+
+            _FDT((fdt_property_cell(fdt, "ibm,chip-id", chip_id)));
+        }
+
         _FDT((fdt_end_node(fdt)));
     }
 
-- 
1.8.4.rc4

Re: [Qemu-devel] [PATCH] spapr: add ibm, chip-id property in device tree

[Alexander Graf]

On 13.03.14 07:29, Alexey Kardashevskiy wrote:
> This adds a "ibm,chip-id" property for CPU nodes which should be the same
> for all cores in the same CPU socket. The recent guest kernels use this
> information to associate threads with sockets.
>
> Refer to the kernel commit 256f2d4b463d3030ebc8d2b54f427543814a2bdc
> for more details.
>
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> ---
>   hw/ppc/spapr.c | 9 +++++++++
>   1 file changed, 9 insertions(+)
>
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index bf46c38..6366230 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -308,6 +308,8 @@ static void *spapr_create_fdt_skel(hwaddr initrd_base,
>       uint32_t interrupt_server_ranges_prop[] = {0, cpu_to_be32(smp_cpus)};
>       int i, smt = kvmppc_smt_threads();
>       unsigned char vec5[] = {0x0, 0x0, 0x0, 0x0, 0x0, 0x80};
> +    QemuOpts *opts = qemu_opts_find(qemu_find_opts("smp-opts"), NULL);
> +    unsigned sockets = opts ? qemu_opt_get_number(opts, "sockets", 0) : 0;
>   
>       fdt = g_malloc0(FDT_MAX_SIZE);
>       _FDT((fdt_create(fdt, FDT_MAX_SIZE)));
> @@ -465,6 +467,13 @@ static void *spapr_create_fdt_skel(hwaddr initrd_base,
>                                  page_sizes_prop, page_sizes_prop_size)));
>           }
>   
> +        if (sockets) {
> +            int cpus_per_socket = smp_cpus / sockets;
> +            uint32_t chip_id = cs->cpu_index / cpus_per_socket;
> +
> +            _FDT((fdt_property_cell(fdt, "ibm,chip-id", chip_id)));
> +        }

Have you verified this works correctly with threads? Also, I don't see 
why we should omit the chip-id when we don't define sockets.


Alex

Re: [Qemu-devel] [PATCH] spapr: add ibm, chip-id property in device tree

[Alexey Kardashevskiy]

On 04/12/2014 02:29 AM, Alexander Graf wrote:
> 
> On 13.03.14 07:29, Alexey Kardashevskiy wrote:
>> This adds a "ibm,chip-id" property for CPU nodes which should be the same
>> for all cores in the same CPU socket. The recent guest kernels use this
>> information to associate threads with sockets.
>>
>> Refer to the kernel commit 256f2d4b463d3030ebc8d2b54f427543814a2bdc
>> for more details.
>>
>> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
>> ---
>>   hw/ppc/spapr.c | 9 +++++++++
>>   1 file changed, 9 insertions(+)
>>
>> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
>> index bf46c38..6366230 100644
>> --- a/hw/ppc/spapr.c
>> +++ b/hw/ppc/spapr.c
>> @@ -308,6 +308,8 @@ static void *spapr_create_fdt_skel(hwaddr initrd_base,
>>       uint32_t interrupt_server_ranges_prop[] = {0, cpu_to_be32(smp_cpus)};
>>       int i, smt = kvmppc_smt_threads();
>>       unsigned char vec5[] = {0x0, 0x0, 0x0, 0x0, 0x0, 0x80};
>> +    QemuOpts *opts = qemu_opts_find(qemu_find_opts("smp-opts"), NULL);
>> +    unsigned sockets = opts ? qemu_opt_get_number(opts, "sockets", 0) : 0;
>>         fdt = g_malloc0(FDT_MAX_SIZE);
>>       _FDT((fdt_create(fdt, FDT_MAX_SIZE)));
>> @@ -465,6 +467,13 @@ static void *spapr_create_fdt_skel(hwaddr initrd_base,
>>                                  page_sizes_prop, page_sizes_prop_size)));
>>           }
>>   +        if (sockets) {
>> +            int cpus_per_socket = smp_cpus / sockets;
>> +            uint32_t chip_id = cs->cpu_index / cpus_per_socket;
>> +
>> +            _FDT((fdt_property_cell(fdt, "ibm,chip-id", chip_id)));
>> +        }
> 
> Have you verified this works correctly with threads? 

Sorry, do not follow you.
-smp X,sockets=Y,threads=Z - what combination of XYZ is suspicious?


> Also, I don't see why
> we should omit the chip-id when we don't define sockets.

Why should we pollute device tree...



-- 
Alexey