From: David Hildenbrand <david@redhat.com>
Let's register a RAM block notifier and react on remap notifications.
Simply re-apply the settings. Warn only when something goes wrong.
Note: qemu_ram_remap() will not remap when RAM_PREALLOC is set. Could be
that hostmem is still missing to update that flag ...
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: William Roche <william.roche@oracle.com>
---
backends/hostmem.c | 29 +++++++++++++++++++++++++++++
include/sysemu/hostmem.h | 1 +
2 files changed, 30 insertions(+)
diff --git a/backends/hostmem.c b/backends/hostmem.c
index bf85d716e5..fbd8708664 100644
--- a/backends/hostmem.c
+++ b/backends/hostmem.c
@@ -361,11 +361,32 @@ static void host_memory_backend_set_prealloc_threads(Object *obj, Visitor *v,
backend->prealloc_threads = value;
}
+static void host_memory_backend_ram_remapped(RAMBlockNotifier *n, void *host,
+ size_t offset, size_t size)
+{
+ HostMemoryBackend *backend = container_of(n, HostMemoryBackend,
+ ram_notifier);
+ Error *err = NULL;
+
+ if (!host_memory_backend_mr_inited(backend) ||
+ memory_region_get_ram_ptr(&backend->mr) != host) {
+ return;
+ }
+
+ host_memory_backend_apply_settings(backend, host + offset, size, &err);
+ if (err) {
+ warn_report_err(err);
+ }
+}
+
static void host_memory_backend_init(Object *obj)
{
HostMemoryBackend *backend = MEMORY_BACKEND(obj);
MachineState *machine = MACHINE(qdev_get_machine());
+ backend->ram_notifier.ram_block_remapped = host_memory_backend_ram_remapped;
+ ram_block_notifier_add(&backend->ram_notifier);
+
/* TODO: convert access to globals to compat properties */
backend->merge = machine_mem_merge(machine);
backend->dump = machine_dump_guest_core(machine);
@@ -379,6 +400,13 @@ static void host_memory_backend_post_init(Object *obj)
object_apply_compat_props(obj);
}
+static void host_memory_backend_finalize(Object *obj)
+{
+ HostMemoryBackend *backend = MEMORY_BACKEND(obj);
+
+ ram_block_notifier_remove(&backend->ram_notifier);
+}
+
bool host_memory_backend_mr_inited(HostMemoryBackend *backend)
{
/*
@@ -595,6 +623,7 @@ static const TypeInfo host_memory_backend_info = {
.instance_size = sizeof(HostMemoryBackend),
.instance_init = host_memory_backend_init,
.instance_post_init = host_memory_backend_post_init,
+ .instance_finalize = host_memory_backend_finalize,
.interfaces = (InterfaceInfo[]) {
{ TYPE_USER_CREATABLE },
{ }
diff --git a/include/sysemu/hostmem.h b/include/sysemu/hostmem.h
index de47ae59e4..062a68c8fc 100644
--- a/include/sysemu/hostmem.h
+++ b/include/sysemu/hostmem.h
@@ -81,6 +81,7 @@ struct HostMemoryBackend {
HostMemPolicy policy;
MemoryRegion mr;
+ RAMBlockNotifier ram_notifier;
};
bool host_memory_backend_mr_inited(HostMemoryBackend *backend);
--
2.43.5On 07.11.24 11:21, “William Roche wrote:
> From: David Hildenbrand <david@redhat.com>
>
> Let's register a RAM block notifier and react on remap notifications.
> Simply re-apply the settings. Warn only when something goes wrong.
>
> Note: qemu_ram_remap() will not remap when RAM_PREALLOC is set. Could be
> that hostmem is still missing to update that flag ...
>
> Signed-off-by: David Hildenbrand <david@redhat.com>
> Signed-off-by: William Roche <william.roche@oracle.com>
> ---
> backends/hostmem.c | 29 +++++++++++++++++++++++++++++
> include/sysemu/hostmem.h | 1 +
> 2 files changed, 30 insertions(+)
>
> diff --git a/backends/hostmem.c b/backends/hostmem.c
> index bf85d716e5..fbd8708664 100644
> --- a/backends/hostmem.c
> +++ b/backends/hostmem.c
> @@ -361,11 +361,32 @@ static void host_memory_backend_set_prealloc_threads(Object *obj, Visitor *v,
> backend->prealloc_threads = value;
> }
>
> +static void host_memory_backend_ram_remapped(RAMBlockNotifier *n, void *host,
> + size_t offset, size_t size)
> +{
> + HostMemoryBackend *backend = container_of(n, HostMemoryBackend,
> + ram_notifier);
> + Error *err = NULL;
> +
> + if (!host_memory_backend_mr_inited(backend) ||
> + memory_region_get_ram_ptr(&backend->mr) != host) {
> + return;
> + }
> +
> + host_memory_backend_apply_settings(backend, host + offset, size, &err);
> + if (err) {
> + warn_report_err(err);
I wonder if we want to fail hard instead, or have a way to tell the
notifier that something wen wrong.
--
Cheers,
David / dhildenb
On 11/12/24 14:45, David Hildenbrand wrote:
> On 07.11.24 11:21, “William Roche wrote:
>> From: David Hildenbrand <david@redhat.com>
>>
>> Let's register a RAM block notifier and react on remap notifications.
>> Simply re-apply the settings. Warn only when something goes wrong.
>>
>> Note: qemu_ram_remap() will not remap when RAM_PREALLOC is set. Could be
>> that hostmem is still missing to update that flag ...
>>
>> Signed-off-by: David Hildenbrand <david@redhat.com>
>> Signed-off-by: William Roche <william.roche@oracle.com>
>> ---
>> backends/hostmem.c | 29 +++++++++++++++++++++++++++++
>> include/sysemu/hostmem.h | 1 +
>> 2 files changed, 30 insertions(+)
>>
>> diff --git a/backends/hostmem.c b/backends/hostmem.c
>> index bf85d716e5..fbd8708664 100644
>> --- a/backends/hostmem.c
>> +++ b/backends/hostmem.c
>> @@ -361,11 +361,32 @@ static void
>> host_memory_backend_set_prealloc_threads(Object *obj, Visitor *v,
>> backend->prealloc_threads = value;
>> }
>> +static void host_memory_backend_ram_remapped(RAMBlockNotifier *n,
>> void *host,
>> + size_t offset, size_t size)
>> +{
>> + HostMemoryBackend *backend = container_of(n, HostMemoryBackend,
>> + ram_notifier);
>> + Error *err = NULL;
>> +
>> + if (!host_memory_backend_mr_inited(backend) ||
>> + memory_region_get_ram_ptr(&backend->mr) != host) {
>> + return;
>> + }
>> +
>> + host_memory_backend_apply_settings(backend, host + offset, size,
>> &err);
>> + if (err) {
>> + warn_report_err(err);
>
> I wonder if we want to fail hard instead, or have a way to tell the
> notifier that something wen wrong.
>
It depends on what the caller would do with this information. Is there a
way to workaround the problem ? (I don't think so)
Can the VM continue to run without doing anything about it ? (Maybe?)
Currently all numa notifiers don't return errors.
This function is only called from ram_block_notify_remap() in
qemu_ram_remap(), I would vote for a "fail hard" in case where the
settings are mandatory to continue.
HTH.
On 12.11.24 19:17, William Roche wrote:
> On 11/12/24 14:45, David Hildenbrand wrote:
>> On 07.11.24 11:21, “William Roche wrote:
>>> From: David Hildenbrand <david@redhat.com>
>>>
>>> Let's register a RAM block notifier and react on remap notifications.
>>> Simply re-apply the settings. Warn only when something goes wrong.
>>>
>>> Note: qemu_ram_remap() will not remap when RAM_PREALLOC is set. Could be
>>> that hostmem is still missing to update that flag ...
>>>
>>> Signed-off-by: David Hildenbrand <david@redhat.com>
>>> Signed-off-by: William Roche <william.roche@oracle.com>
>>> ---
>>> backends/hostmem.c | 29 +++++++++++++++++++++++++++++
>>> include/sysemu/hostmem.h | 1 +
>>> 2 files changed, 30 insertions(+)
>>>
>>> diff --git a/backends/hostmem.c b/backends/hostmem.c
>>> index bf85d716e5..fbd8708664 100644
>>> --- a/backends/hostmem.c
>>> +++ b/backends/hostmem.c
>>> @@ -361,11 +361,32 @@ static void
>>> host_memory_backend_set_prealloc_threads(Object *obj, Visitor *v,
>>> backend->prealloc_threads = value;
>>> }
>>> +static void host_memory_backend_ram_remapped(RAMBlockNotifier *n,
>>> void *host,
>>> + size_t offset, size_t size)
>>> +{
>>> + HostMemoryBackend *backend = container_of(n, HostMemoryBackend,
>>> + ram_notifier);
>>> + Error *err = NULL;
>>> +
>>> + if (!host_memory_backend_mr_inited(backend) ||
>>> + memory_region_get_ram_ptr(&backend->mr) != host) {
>>> + return;
>>> + }
>>> +
>>> + host_memory_backend_apply_settings(backend, host + offset, size,
>>> &err);
>>> + if (err) {
>>> + warn_report_err(err);
>>
>> I wonder if we want to fail hard instead, or have a way to tell the
>> notifier that something wen wrong.
>>
>
> It depends on what the caller would do with this information. Is there a
> way to workaround the problem ? (I don't think so)
Primarily only preallocation will fail, and that ...
> Can the VM continue to run without doing anything about it ? (Maybe?)
>
... will make crash the QEMU at some point later (SIGBUS), which is very
bad.
> Currently all numa notifiers don't return errors.
>
> This function is only called from ram_block_notify_remap() in
> qemu_ram_remap(), I would vote for a "fail hard" in case where the
> settings are mandatory to continue.
"fail hard" is likely the best approach for now.
--
Cheers,
David / dhildenb
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