On Tue, Mar 05, 2019 at 08:17:03PM +0800, Kairui Song wrote: > diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c > index 7abb09e2eeb8..34aa1e953dfc 100644 > --- a/arch/x86/hyperv/hv_init.c > +++ b/arch/x86/hyperv/hv_init.c > @@ -406,6 +406,12 @@ void hyperv_cleanup(void) > /* Reset our OS id */ > wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0); > > + /* Cleanup hypercall page reference before reset the page */ > + hv_hypercall_pg = NULL; > + > + /* Make sure page reference is cleared before wrmsr */
This comment forgets to tell us who cares about this. And why the wrmsr itself isn't serializing enough. > + wmb(); > + > /* Reset the hypercall page */ > hypercall_msr.as_uint64 = 0; > wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); That looks like a fake MSR; and you're telling me that VMEXIT doesn't serialize?
