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mshv: unmap debugfs stats pages on kexec

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On L1VH, debugfs stats pages are overlay pages: the kernel allocates
them and registers the GPAs with the hypervisor via
HVCALL_MAP_STATS_PAGE2. These overlay mappings persist in the
hypervisor across kexec. If the kexec'd kernel reuses those physical
pages, the hypervisor's overlay semantics cause a machine check
exception.

Fix this by calling mshv_debugfs_exit() from the reboot notifier,
which issues HVCALL_UNMAP_STATS_PAGE for each mapped stats page before
kexec. This releases the overlay bindings so the physical pages can be
safely reused. Guard mshv_debugfs_exit() against being called when
init failed.

Signed-off-by: Jork Loeser <jloeser@linux.microsoft.com>
Reviewed-by: Anirudh Rayabharam (Microsoft) <anirudh@anirudhrb.com>
Reviewed-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
This commit is contained in:
Jork Loeser
2026-04-27 14:38:54 -07:00
committed by Wei Liu
parent efe0fb8c3f
commit 6e55a8d9f2
2 changed files with 7 additions and 1 deletions
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7
drivers/hv/mshv_debugfs.c
View File

@@ -674,8 +674,10 @@ int __init mshv_debugfs_init(void)
mshv_debugfs = debugfs_create_dir("mshv", NULL);
if (IS_ERR(mshv_debugfs)) {
err = PTR_ERR(mshv_debugfs);
mshv_debugfs = NULL;
pr_err("%s: failed to create debugfs directory\n", __func__);
return PTR_ERR(mshv_debugfs);
return err;
}
if (hv_root_partition()) {
@@ -710,6 +712,9 @@ int __init mshv_debugfs_init(void)
void mshv_debugfs_exit(void)
{
if (!mshv_debugfs)
return;
mshv_debugfs_parent_partition_remove();
if (hv_root_partition()) {

1
drivers/hv/mshv_synic.c
View File

@@ -723,6 +723,7 @@ mshv_unregister_doorbell(u64 partition_id, int doorbell_portid)
static int mshv_synic_reboot_notify(struct notifier_block *nb,
unsigned long code, void *unused)
{
mshv_debugfs_exit();
cpuhp_remove_state(synic_cpuhp_online);
return 0;
}