[PATCH AUTOSEL 5.6 07/47] x86/hyperv: Properly suspend/resume reenlightenment notifications

Sasha Levin
2020-05-28T12:11:09Z

From: Vitaly Kuznetsov <vkuznets@redhat.com>

[ Upstream commit 38dce4195f0daefb566279fd9fd51e1fbd62ae1b ]

Errors during hibernation with reenlightenment notifications enabled were
reported:

[ 51.730435] PM: hibernation entry
[ 51.737435] PM: Syncing filesystems ...
...
[ 54.102216] Disabling non-boot CPUs ...
[ 54.106633] smpboot: CPU 1 is now offline
[ 54.110006] unchecked MSR access error: WRMSR to 0x40000106 (tried to
write 0x47c72780000100ee) at rIP: 0xffffffff90062f24
native_write_msr+0x4/0x20)
[ 54.110006] Call Trace:
[ 54.110006] hv_cpu_die+0xd9/0xf0
...

Normally, hv_cpu_die() just reassigns reenlightenment notifications to some
other CPU when the CPU receiving them goes offline. Upon hibernation, there
is no other CPU which is still online so cpumask_any_but(cpu_online_mask)
returns >= nr_cpu_ids and using it as hv_vp_index index is incorrect.
Disable the feature when cpumask_any_but() fails.

Also, as we now disable reenlightenment notifications upon hibernation we
need to restore them on resume. Check if hv_reenlightenment_cb was
previously set and restore from hv_resume().

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Dexuan Cui <decui@microsoft.com>
Reviewed-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
Link: https://lore.kernel.org/r/20200512160153.134467-1-vkuznets@redhat.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/x86/hyperv/hv_init.c | 19 +++++++++++++++++--
1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index fd51bac11b46..acf76b466db6 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -226,10 +226,18 @@ static int hv_cpu_die(unsigned int cpu)

rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
if (re_ctrl.target_vp == hv_vp_index[cpu]) {
- /* Reassign to some other online CPU */
+ /*
+ * Reassign reenlightenment notifications to some other online
+ * CPU or just disable the feature if there are no online CPUs
+ * left (happens on hibernation).
+ */
new_cpu = cpumask_any_but(cpu_online_mask, cpu);

- re_ctrl.target_vp = hv_vp_index[new_cpu];
+ if (new_cpu < nr_cpu_ids)
+ re_ctrl.target_vp = hv_vp_index[new_cpu];
+ else
+ re_ctrl.enabled = 0;
+
wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
}

@@ -293,6 +301,13 @@ static void hv_resume(void)

hv_hypercall_pg = hv_hypercall_pg_saved;
hv_hypercall_pg_saved = NULL;
+
+ /*
+ * Reenlightenment notifications are disabled by hv_cpu_die(0),
+ * reenable them here if hv_reenlightenment_cb was previously set.
+ */
+ if (hv_reenlightenment_cb)
+ set_hv_tscchange_cb(hv_reenlightenment_cb);
}

/* Note: when the ops are called, only CPU0 is online and IRQs are disabled. */
--
2.25.1