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Message-ID: <c80a76eb-1e10-95f7-def1-5eb26d66efb2@linux.ibm.com>
Date: Tue, 27 Apr 2021 19:28:51 +0200
From: Laurent Dufour <ldufour@...ux.ibm.com>
To: Tyrel Datwyler <tyreld@...ux.ibm.com>, mpe@...erman.id.au,
benh@...nel.crashing.org, paulus@...ba.org
Cc: nathanl@...ux.ibm.com, linuxppc-dev@...ts.ozlabs.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] pseries/drmem: update LMBs after LPM
Le 27/04/2021 à 19:01, Tyrel Datwyler a écrit :
> On 4/27/21 8:01 AM, Laurent Dufour wrote:
>> After a LPM, the device tree node ibm,dynamic-reconfiguration-memory may be
>> updated by the hypervisor in the case the NUMA topology of the LPAR's
>> memory is updated.
>>
>> This is caught by the kernel, but the memory's node is updated because
>> there is no way to move a memory block between nodes.
>>
>> If later a memory block is added or removed, drmem_update_dt() is called
>> and it is overwriting the DT node to match the added or removed LMB. But
>> the LMB's associativity node has not been updated after the DT node update
>> and thus the node is overwritten by the Linux's topology instead of the
>> hypervisor one.
>>
>> Introduce a hook called when the ibm,dynamic-reconfiguration-memory node is
>> updated to force an update of the LMB's associativity.
>>
>> Signed-off-by: Laurent Dufour <ldufour@...ux.ibm.com>
>> ---
>> arch/powerpc/include/asm/drmem.h | 1 +
>> arch/powerpc/mm/drmem.c | 48 +++++++++++++++++++++++
>> arch/powerpc/platforms/pseries/mobility.c | 9 +++++
>> 3 files changed, 58 insertions(+)
>>
>> diff --git a/arch/powerpc/include/asm/drmem.h b/arch/powerpc/include/asm/drmem.h
>> index bf2402fed3e0..55c2c25085b0 100644
>> --- a/arch/powerpc/include/asm/drmem.h
>> +++ b/arch/powerpc/include/asm/drmem.h
>> @@ -111,6 +111,7 @@ int drmem_update_dt(void);
>> int __init
>> walk_drmem_lmbs_early(unsigned long node, void *data,
>> int (*func)(struct drmem_lmb *, const __be32 **, void *));
>> +void drmem_update_lmbs(void);
>> #endif
>>
>> static inline void invalidate_lmb_associativity_index(struct drmem_lmb *lmb)
>> diff --git a/arch/powerpc/mm/drmem.c b/arch/powerpc/mm/drmem.c
>> index 9af3832c9d8d..46074bdfdb3c 100644
>> --- a/arch/powerpc/mm/drmem.c
>> +++ b/arch/powerpc/mm/drmem.c
>> @@ -307,6 +307,54 @@ int __init walk_drmem_lmbs_early(unsigned long node, void *data,
>> return ret;
>> }
>>
>> +/*
>> + * Update the LMB associativity index.
>> + */
>> +static int update_lmb(struct drmem_lmb *updated_lmb,
>> + __maybe_unused const __be32 **usm,
>> + __maybe_unused void *data)
>> +{
>> + struct drmem_lmb *lmb;
>> +
>> + /*
>> + * Brut force there may be better way to fetch the LMB
>> + */
>> + for_each_drmem_lmb(lmb) {
>> + if (lmb->drc_index != updated_lmb->drc_index)
>> + continue;
>> +
>> + lmb->aa_index = updated_lmb->aa_index;
>> + break;
>> + }
>> + return 0;
>> +}
>> +
>> +/*
>> + * Update the LMB associativity index.
>> + *
>> + * This needs to be called when the hypervisor is updating the
>> + * dynamic-reconfiguration-memory node property.
>> + */
>> +void drmem_update_lmbs(void)
>> +{
>> + struct device_node *node;
>> + const __be32 *prop;
>> +
>> + node = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");
>> + if (!node)
>> + return;
>> +
>> + prop = of_get_property(node, "ibm,dynamic-memory", NULL);
>> + if (prop) {
>> + __walk_drmem_v1_lmbs(prop, NULL, NULL, update_lmb);
>> + } else {
>> + prop = of_get_property(node, "ibm,dynamic-memory-v2", NULL);
>> + if (prop)
>> + __walk_drmem_v2_lmbs(prop, NULL, NULL, update_lmb);
>> + }
>> +
>> + of_node_put(node);
>> +}
>> #endif
>>
>> static int init_drmem_lmb_size(struct device_node *dn)
>> diff --git a/arch/powerpc/platforms/pseries/mobility.c b/arch/powerpc/platforms/pseries/mobility.c
>> index ea4d6a660e0d..c68eccc6e8df 100644
>> --- a/arch/powerpc/platforms/pseries/mobility.c
>> +++ b/arch/powerpc/platforms/pseries/mobility.c
>> @@ -25,6 +25,7 @@
>>
>> #include <asm/machdep.h>
>> #include <asm/rtas.h>
>> +#include <asm/drmem.h>
>> #include "pseries.h"
>> #include "../../kernel/cacheinfo.h"
>>
>> @@ -237,6 +238,7 @@ int pseries_devicetree_update(s32 scope)
>> __be32 *data;
>> int update_nodes_token;
>> int rc;
>> + bool drmem_updated = false;
>>
>> update_nodes_token = rtas_token("ibm,update-nodes");
>> if (update_nodes_token == RTAS_UNKNOWN_SERVICE)
>> @@ -271,6 +273,10 @@ int pseries_devicetree_update(s32 scope)
>> continue;
>> }
>>
>> + if (!strcmp(np->full_name,
>> + "ibm,dynamic-reconfiguration-memory"))
>> + drmem_updated = true;
>
> Is there a reason that we can't use the existing pseries_memory_notifier()
> callback in pseries/hotplug-memory.c to trigger the drmem_update_lmbs() when
> either the ibm,dynamic-memory or ibm,dynamic-memory-v2 properties are updated?
Thanks a lot Tyrel!
That's far more elegant, I'll send a v2 soon.
Laurent.
> Something like:
>
> static int pseries_memory_notifier(struct notifier_block *nb,
> unsigned long action, void *data)
> {
> struct of_reconfig_data *rd = data;
> int err = 0;
>
> switch (action) {
> case OF_RECONFIG_ATTACH_NODE:
> err = pseries_add_mem_node(rd->dn);
> break;
> case OF_RECONFIG_DETACH_NODE:
> err = pseries_remove_mem_node(rd->dn);
> break;
> case OF_RECONFIG_UPDATE_PROPERTY:
> if (!strcmp(rd->dn->full_name, "ibm,dynamic-reconfiguration-memory"));
> drmem_update_lmbs(rd->prop);
> break;
> }
> return notifier_from_errno(err);
> }
>
> Your drmem_update_lmbs() would need to be updated to take a property and to
> check the property name against ibm,dyanmic-memory[-v2].
>
> -Tyrel
>
>> +
>> switch (action) {
>> case DELETE_DT_NODE:
>> delete_dt_node(np);
>> @@ -293,6 +299,9 @@ int pseries_devicetree_update(s32 scope)
>> } while (rc == 1);
>>
>> kfree(rtas_buf);
>> +
>> + if (drmem_updated)
>> + drmem_update_lmbs();
>> return rc;
>> }
>>
>
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