From: Dexuan Cui <decui@xxxxxxxxxxxxx> Sent: Monday, December 21, 2020 10:56 PM
>
> Currently the kexec kernel can panic or hang due to 2 causes:
>
> 1) hv_cpu_die() is not called upon kexec, so the hypervisor corrupts the
> old VP Assist Pages when the kexec kernel runs. The same issue is fixed
> for hibernation in commit 421f090c819d ("x86/hyperv: Suspend/resume the
> VP assist page for hibernation"). Now fix it for kexec.
>
> 2) hyperv_cleanup() is called too early. In the kexec path, the other CPUs
> are stopped in hv_machine_shutdown() -> native_machine_shutdown(), so
> between hv_kexec_handler() and native_machine_shutdown(), the other CPUs
> can still try to access the hypercall page and cause panic. The workaround
> "hv_hypercall_pg = NULL;" in hyperv_cleanup() is unreliabe. Move
> hyperv_cleanup() to a better place.
>
> Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx>
> ---
>
> Changes in v2:
> Improved the commit log as Michael Kelley suggested.
> No change to v1 otherwise.
>
> arch/x86/hyperv/hv_init.c | 4 ++++
> arch/x86/include/asm/mshyperv.h | 2 ++
> arch/x86/kernel/cpu/mshyperv.c | 18 ++++++++++++++++++
> drivers/hv/vmbus_drv.c | 2 --
> 4 files changed, 24 insertions(+), 2 deletions(-)
>
Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
