From: Babu Moger <babu.moger@amd.com>
To: Igor Mammedov <imammedo@redhat.com>
Cc: qemu-devel@nongnu.org, pbonzini@redhat.com, mst@redhat.com,
ehabkost@redhat.com, rth@twiddle.net
Subject: Re: [PATCH v4 3/3] hw/i386: Remove node_id, nr_nodes and nodes_per_pkg from topology
Date: Thu, 20 Aug 2020 10:24:01 -0500 [thread overview]
Message-ID: <c0bcc1a6-1d84-a6e7-e468-d5b437c1b254@amd.com> (raw)
In-Reply-To: <20200820145757.2aa8752d@redhat.com>
On 8/20/20 7:57 AM, Igor Mammedov wrote:
> On Wed, 19 Aug 2020 17:42:58 -0500
> Babu Moger <babu.moger@amd.com> wrote:
>
>> On 8/19/20 7:18 AM, Igor Mammedov wrote:
>>> On Fri, 14 Aug 2020 16:39:40 -0500
>>> Babu Moger <babu.moger@amd.com> wrote:
>>>
>>>> Remove node_id, nr_nodes and nodes_per_pkg from topology. Use
>>>> die_id, nr_dies and dies_per_pkg which is already available.
>>>> Removes the confusion over two variables.
>>>>
>>>> With node_id removed in topology the uninitialized memory issue
>>>> with -device and CPU hotplug will be fixed.
>>>>
>>>> Link: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbugzilla.redhat.com%2Fshow_bug.cgi%3Fid%3D1828750&data=02%7C01%7Cbabu.moger%40amd.com%7Cf7ad03f0c04d44dd104c08d84508b0b8%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637335250919794679&sdata=JT8rq3Ag29WMgD8p2v2tm%2Fmdo8nBnLHb8V7QUbCHCLs%3D&reserved=0
>>>> Signed-off-by: Babu Moger <babu.moger@amd.com>
>>>> ---
>>>> hw/i386/pc.c | 1 -
>>>> hw/i386/x86.c | 1 -
>>>> include/hw/i386/topology.h | 40 +++++++++-------------------------------
>>>> target/i386/cpu.c | 11 +++--------
>>>> target/i386/cpu.h | 1 -
>>>> 5 files changed, 12 insertions(+), 42 deletions(-)
>>>>
>>>> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
>>>> index 47c5ca3e34..0ae5cb3af4 100644
>>>> --- a/hw/i386/pc.c
>>>> +++ b/hw/i386/pc.c
>>>> @@ -1498,7 +1498,6 @@ static void pc_cpu_pre_plug(HotplugHandler *hotplug_dev,
>>>> init_topo_info(&topo_info, x86ms);
>>>>
>>>> env->nr_dies = x86ms->smp_dies;
>>>> - env->nr_nodes = topo_info.nodes_per_pkg;
>>>> env->pkg_offset = x86ms->apicid_pkg_offset(&topo_info);
>>>>
>>>> /*
>>>> diff --git a/hw/i386/x86.c b/hw/i386/x86.c
>>>> index e90c42d2fc..4efa1f8b87 100644
>>>> --- a/hw/i386/x86.c
>>>> +++ b/hw/i386/x86.c
>>>> @@ -62,7 +62,6 @@ inline void init_topo_info(X86CPUTopoInfo *topo_info,
>>>> {
>>>> MachineState *ms = MACHINE(x86ms);
>>>>
>>>> - topo_info->nodes_per_pkg = ms->numa_state->num_nodes / ms->smp.sockets;
>>>> topo_info->dies_per_pkg = x86ms->smp_dies;
>>>> topo_info->cores_per_die = ms->smp.cores;
>>>> topo_info->threads_per_core = ms->smp.threads;
>>>> diff --git a/include/hw/i386/topology.h b/include/hw/i386/topology.h
>>>> index 07239f95f4..05ddde7ba0 100644
>>>> --- a/include/hw/i386/topology.h
>>>> +++ b/include/hw/i386/topology.h
>>>> @@ -47,14 +47,12 @@ typedef uint32_t apic_id_t;
>>>>
>>>> typedef struct X86CPUTopoIDs {
>>>> unsigned pkg_id;
>>>> - unsigned node_id;
>>>> unsigned die_id;
>>>> unsigned core_id;
>>>> unsigned smt_id;
>>>> } X86CPUTopoIDs;
>>>>
>>>> typedef struct X86CPUTopoInfo {
>>>> - unsigned nodes_per_pkg;
>>>> unsigned dies_per_pkg;
>>>> unsigned cores_per_die;
>>>> unsigned threads_per_core;
>>>> @@ -89,11 +87,6 @@ static inline unsigned apicid_die_width(X86CPUTopoInfo *topo_info)
>>>> return apicid_bitwidth_for_count(topo_info->dies_per_pkg);
>>>> }
>>>>
>>>> -/* Bit width of the node_id field per socket */
>>>> -static inline unsigned apicid_node_width_epyc(X86CPUTopoInfo *topo_info)
>>>> -{
>>>> - return apicid_bitwidth_for_count(MAX(topo_info->nodes_per_pkg, 1));
>>>> -}
>>>> /* Bit offset of the Core_ID field
>>>> */
>>>> static inline unsigned apicid_core_offset(X86CPUTopoInfo *topo_info)
>>>> @@ -114,30 +107,23 @@ static inline unsigned apicid_pkg_offset(X86CPUTopoInfo *topo_info)
>>>> return apicid_die_offset(topo_info) + apicid_die_width(topo_info);
>>>> }
>>>>
>>>> -#define NODE_ID_OFFSET 3 /* Minimum node_id offset if numa configured */
>>>> +#define EPYC_DIE_OFFSET 3 /* Minimum die_id offset if numa configured */
>>> ^^
>>>
>>> from EPYC's pov NUMA is always configured, there no 'if'
>>>
>>> but I have a question, is it possible to drop EPYC_DIE_OFFSET
>>> and reuse apicid_die_offset(), will it break something?
>>
>> Yes. I am also thinking about it. We can go back to existing
>> apicid_die_width().
>
> Given we are using die_id now, we probably can get rid of all
> topo hooks to generate apicid.
Sure. Will start working on it. thanks
>
>> Looking back again, I think all these code changes related to node_id is
>> causing more issues than fixes. We have added all these code to handle
>> some non- SPECed configurations like
>> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbugzilla.redhat.com%2Fshow_bug.cgi%3Fid%3D1728166&data=02%7C01%7Cbabu.moger%40amd.com%7Cf7ad03f0c04d44dd104c08d84508b0b8%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637335250919794679&sdata=pOGISuQdHxFm5dEjybkGuDHfPCO1QqwE%2B%2FHR0fOAqnQ%3D&reserved=0.
>>
>> Going forward it might create even more issues. Now, I think we should go
>> back and remove all these changes and just use the default decoding. Most
>> of the SPECed configuration would work just fine. With some non-SPECed
>> user inputs, it will create some sub-optimal configuration. If we can live
>> with that we will be just fine. I did not anticipate all these problems
>> when I originally started this work. Sorry, my bad.
>
> Topology code is complex and sometimes it's easier to add a new thing,
> it's just that not every time it turns out as expected.
> We overlooked posiblilty to reuse die-id, which has lead to more
> complex and fragile outcome.
>
> But it's fine, as long as it gets fixed in the end.
Sure. Thanks.
>
>
>
>>> The reason for question is that, we (deviating from spec)
>>> do allow for unbound core/threads number so die_id, already could
>>> be shifted beyound ApicId[5:4], likewise we do allow for unbound
>>> sockets so ApicId[6] is also out of spec.
>>> If we are fine with ApicId being encoded in these cases out of
>>> spec, then why should we insist on DIE_OFFSET minumum at all?
>>> Why not just allow existing apicid_die_width() to encode die_id?
>>>
>>> In this case it will produce SPECed ApicId if user has provided
>>> -smp that matches currently released EPYC's and in all other cases
>>> it will be out of spec ApicId like when we set sockets/cores/trheads
>>> to out of spec values.
>>>
>>>> /*
>>>> - * Bit offset of the node_id field
>>>> - *
>>>> - * Make sure nodes_per_pkg > 0 if numa configured else zero.
>>>> + * Bit offset of the die_id field
>>>> */
>>>> -static inline unsigned apicid_node_offset_epyc(X86CPUTopoInfo *topo_info)
>>>> +static inline unsigned apicid_die_offset_epyc(X86CPUTopoInfo *topo_info)
>>>> {
>>>> - unsigned offset = apicid_die_offset(topo_info) +
>>>> - apicid_die_width(topo_info);
>>>> + unsigned offset = apicid_core_offset(topo_info) +
>>>> + apicid_core_width(topo_info);
>>>>
>>>> - if (topo_info->nodes_per_pkg) {
>>>> - return MAX(NODE_ID_OFFSET, offset);
>>>> - } else {
>>>> - return offset;
>>>> - }
>>>> + return MAX(EPYC_DIE_OFFSET, offset);
>>>> }
>>>>
>>>> /* Bit offset of the Pkg_ID (socket ID) field */
>>>> static inline unsigned apicid_pkg_offset_epyc(X86CPUTopoInfo *topo_info)
>>>> {
>>>> - return apicid_node_offset_epyc(topo_info) +
>>>> - apicid_node_width_epyc(topo_info);
>>>> + return apicid_die_offset_epyc(topo_info) + apicid_die_width(topo_info);
>>>> }
>>>>
>>>> /*
>>>> @@ -150,8 +136,7 @@ x86_apicid_from_topo_ids_epyc(X86CPUTopoInfo *topo_info,
>>>> const X86CPUTopoIDs *topo_ids)
>>>> {
>>>> return (topo_ids->pkg_id << apicid_pkg_offset_epyc(topo_info)) |
>>>> - (topo_ids->node_id << apicid_node_offset_epyc(topo_info)) |
>>>> - (topo_ids->die_id << apicid_die_offset(topo_info)) |
>>>> + (topo_ids->die_id << apicid_die_offset_epyc(topo_info)) |
>>>> (topo_ids->core_id << apicid_core_offset(topo_info)) |
>>>> topo_ids->smt_id;
>>>> }
>>>> @@ -160,15 +145,11 @@ static inline void x86_topo_ids_from_idx_epyc(X86CPUTopoInfo *topo_info,
>>>> unsigned cpu_index,
>>>> X86CPUTopoIDs *topo_ids)
>>>> {
>>>> - unsigned nr_nodes = MAX(topo_info->nodes_per_pkg, 1);
>>>> unsigned nr_dies = topo_info->dies_per_pkg;
>>>> unsigned nr_cores = topo_info->cores_per_die;
>>>> unsigned nr_threads = topo_info->threads_per_core;
>>>> - unsigned cores_per_node = DIV_ROUND_UP((nr_dies * nr_cores * nr_threads),
>>>> - nr_nodes);
>>>>
>>>> topo_ids->pkg_id = cpu_index / (nr_dies * nr_cores * nr_threads);
>>>> - topo_ids->node_id = (cpu_index / cores_per_node) % nr_nodes;
>>>> topo_ids->die_id = cpu_index / (nr_cores * nr_threads) % nr_dies;
>>>> topo_ids->core_id = cpu_index / nr_threads % nr_cores;
>>>> topo_ids->smt_id = cpu_index % nr_threads;
>>>> @@ -188,11 +169,8 @@ static inline void x86_topo_ids_from_apicid_epyc(apic_id_t apicid,
>>>> (apicid >> apicid_core_offset(topo_info)) &
>>>> ~(0xFFFFFFFFUL << apicid_core_width(topo_info));
>>>> topo_ids->die_id =
>>>> - (apicid >> apicid_die_offset(topo_info)) &
>>>> + (apicid >> apicid_die_offset_epyc(topo_info)) &
>>>> ~(0xFFFFFFFFUL << apicid_die_width(topo_info));
>>>> - topo_ids->node_id =
>>>> - (apicid >> apicid_node_offset_epyc(topo_info)) &
>>>> - ~(0xFFFFFFFFUL << apicid_node_width_epyc(topo_info));
>>>> topo_ids->pkg_id = apicid >> apicid_pkg_offset_epyc(topo_info);
>>>> }
>>>>
>>>> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
>>>> index c892432cae..ba0a24f6b8 100644
>>>> --- a/target/i386/cpu.c
>>>> +++ b/target/i386/cpu.c
>>>> @@ -345,7 +345,6 @@ static void encode_cache_cpuid8000001d(CPUCacheInfo *cache,
>>>> uint32_t *ecx, uint32_t *edx)
>>>> {
>>>> uint32_t l3_cores;
>>>> - unsigned nodes = MAX(topo_info->nodes_per_pkg, 1);
>>>>
>>>> assert(cache->size == cache->line_size * cache->associativity *
>>>> cache->partitions * cache->sets);
>>>> @@ -355,10 +354,9 @@ static void encode_cache_cpuid8000001d(CPUCacheInfo *cache,
>>>>
>>>> /* L3 is shared among multiple cores */
>>>> if (cache->level == 3) {
>>>> - l3_cores = DIV_ROUND_UP((topo_info->dies_per_pkg *
>>>> - topo_info->cores_per_die *
>>>> + l3_cores = DIV_ROUND_UP((topo_info->cores_per_die *
>>>> topo_info->threads_per_core),
>>>> - nodes);
>>>> + topo_info->dies_per_pkg);
>>>> *eax |= (l3_cores - 1) << 14;
>>>> } else {
>>>> *eax |= ((topo_info->threads_per_core - 1) << 14);
>>>> @@ -387,7 +385,6 @@ static void encode_topo_cpuid8000001e(X86CPUTopoInfo *topo_info, X86CPU *cpu,
>>>> uint32_t *ecx, uint32_t *edx)
>>>> {
>>>> X86CPUTopoIDs topo_ids = {0};
>>>> - unsigned long nodes = MAX(topo_info->nodes_per_pkg, 1);
>>>>
>>>> x86_topo_ids_from_apicid_epyc(cpu->apic_id, topo_info, &topo_ids);
>>>>
>>>> @@ -433,7 +430,7 @@ static void encode_topo_cpuid8000001e(X86CPUTopoInfo *topo_info, X86CPU *cpu,
>>>> * NodeId is combination of node and socket_id which is already decoded
>>>> * in apic_id. Just use it by shifting.
>>>> */
>>>> - *ecx = ((nodes - 1) << 8) | cpu->node_id;
>>>> + *ecx = ((topo_info->dies_per_pkg - 1) << 8) | cpu->node_id;
>>>> *edx = 0;
>>>> }
>>>>
>>>> @@ -5484,7 +5481,6 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
>>>> uint32_t signature[3];
>>>> X86CPUTopoInfo topo_info;
>>>>
>>>> - topo_info.nodes_per_pkg = env->nr_nodes;
>>>> topo_info.dies_per_pkg = env->nr_dies;
>>>> topo_info.cores_per_die = cs->nr_cores;
>>>> topo_info.threads_per_core = cs->nr_threads;
>>>> @@ -6944,7 +6940,6 @@ static void x86_cpu_initfn(Object *obj)
>>>> FeatureWord w;
>>>>
>>>> env->nr_dies = 1;
>>>> - env->nr_nodes = 1;
>>>> cpu_set_cpustate_pointers(cpu);
>>>>
>>>> object_property_add(obj, "family", "int",
>>>> diff --git a/target/i386/cpu.h b/target/i386/cpu.h
>>>> index e1a5c174dc..4c89bee8d1 100644
>>>> --- a/target/i386/cpu.h
>>>> +++ b/target/i386/cpu.h
>>>> @@ -1629,7 +1629,6 @@ typedef struct CPUX86State {
>>>> TPRAccess tpr_access_type;
>>>>
>>>> unsigned nr_dies;
>>>> - unsigned nr_nodes;
>>>> unsigned pkg_offset;
>>>> } CPUX86State;
>>>>
>>>>
>>>>
>>>
>>
>
next prev parent reply other threads:[~2020-08-20 15:40 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-14 21:39 [PATCH v4 0/3] Modify AMD topology to use socket/dies/core/thread model Babu Moger
2020-08-14 21:39 ` [PATCH v4 1/3] i386: Simplify CPUID_8000_001E for AMD Babu Moger
2020-08-14 21:39 ` [PATCH v4 2/3] hw/i386: Update the EPYC topology to use socket/dies/core/thread model Babu Moger
2020-08-19 11:25 ` Igor Mammedov
2020-08-19 22:10 ` Babu Moger
2020-08-14 21:39 ` [PATCH v4 3/3] hw/i386: Remove node_id, nr_nodes and nodes_per_pkg from topology Babu Moger
2020-08-19 12:18 ` Igor Mammedov
2020-08-19 22:42 ` Babu Moger
2020-08-20 12:57 ` Igor Mammedov
2020-08-20 15:24 ` Babu Moger [this message]
2020-08-15 17:12 ` [PATCH v4 0/3] Modify AMD topology to use socket/dies/core/thread model no-reply
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