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@xxxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: William Roche <william.roche@xxxxxxxxxx>
---
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
