2022-03-01 15:40:24

by Andrea Parri

Subject: [PATCH] Drivers: hv: vmbus: Deactivate sysctl_record_panic_msg by default in isolated guests

hv_panic_page might contain guest-sensitive information, do not dump it
over to Hyper-V by default in isolated guests.

While at it, update some comments in hyperv_{panic,die}_event().

Reported-by: Dexuan Cui <[email protected]>
Signed-off-by: Andrea Parri (Microsoft) <[email protected]>
---
drivers/hv/vmbus_drv.c | 18 ++++++++++++------
1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 12a2b37e87f30..a963b970ffb2f 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -77,8 +77,8 @@ static int hyperv_panic_event(struct notifier_block *nb, unsigned long val,

/*
* Hyper-V should be notified only once about a panic. If we will be
- * doing hyperv_report_panic_msg() later with kmsg data, don't do
- * the notification here.
+ * doing hv_kmsg_dump() with kmsg data later, don't do the notification
+ * here.
*/
if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE
&& hyperv_report_reg()) {
@@ -100,8 +100,8 @@ static int hyperv_die_event(struct notifier_block *nb, unsigned long val,

/*
* Hyper-V should be notified only once about a panic. If we will be
- * doing hyperv_report_panic_msg() later with kmsg data, don't do
- * the notification here.
+ * doing hv_kmsg_dump() with kmsg data later, don't do the notification
+ * here.
*/
if (hyperv_report_reg())
hyperv_report_panic(regs, val, true);
@@ -1546,14 +1546,20 @@ static int vmbus_bus_init(void)
if (ret)
goto err_connect;

+ if (hv_is_isolation_supported())
+ sysctl_record_panic_msg = 0;
+
/*
* Only register if the crash MSRs are available
*/
if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE) {
u64 hyperv_crash_ctl;
/*
- * Sysctl registration is not fatal, since by default
- * reporting is enabled.
+ * Panic message recording (sysctl_record_panic_msg)
+ * is enabled by default in non-isolated guests and
+ * disabled by default in isolated guests; the panic
+ * message recording won't be available in isolated
+ * guests should the following registration fail.
*/
hv_ctl_table_hdr = register_sysctl_table(hv_root_table);
if (!hv_ctl_table_hdr)
--
2.25.1

2022-03-02 11:35:19

by Dexuan Cui

Subject: RE: [PATCH] Drivers: hv: vmbus: Deactivate sysctl_record_panic_msg by default in isolated guests

> From: Andrea Parri (Microsoft) <[email protected]>
> Sent: Tuesday, March 1, 2022 6:12 AM
> ...
> hv_panic_page might contain guest-sensitive information, do not dump it
> over to Hyper-V by default in isolated guests.
>
> While at it, update some comments in hyperv_{panic,die}_event().
>
> Reported-by: Dexuan Cui <[email protected]>
> Signed-off-by: Andrea Parri (Microsoft) <[email protected]>
> ---

Reviewed-by: Dexuan Cui <[email protected]>

2022-03-29 23:26:46

by Wei Liu

Subject: Re: [PATCH] Drivers: hv: vmbus: Deactivate sysctl_record_panic_msg by default in isolated guests

On Tue, Mar 01, 2022 at 08:29:43PM +0000, Dexuan Cui wrote:
> > From: Andrea Parri (Microsoft) <[email protected]>
> > Sent: Tuesday, March 1, 2022 6:12 AM
> > ...
> > hv_panic_page might contain guest-sensitive information, do not dump it
> > over to Hyper-V by default in isolated guests.
> >
> > While at it, update some comments in hyperv_{panic,die}_event().
> >
> > Reported-by: Dexuan Cui <[email protected]>
> > Signed-off-by: Andrea Parri (Microsoft) <[email protected]>
> > ---
>
> Reviewed-by: Dexuan Cui <[email protected]>

Applied to hyperv-fixes. Thanks.