From: Sasha Levin <sashal@xxxxxxxxxx> Sent: Friday, November 18, 2022 6:11 PM > > From: Anirudh Rayabharam <anrayabh@xxxxxxxxxxxxxxxxxxx> > > [ Upstream commit 2982635a0b3d08d6fee2ff05632206286df0e703 ] > > hyperv_cleanup resets the hypercall page by setting the MSR to 0. However, > the root partition is not allowed to write to the GPA bits of the MSR. > Instead, it uses the hypercall page provided by the MSR. Similar is the > case with the reference TSC MSR. > > Clear only the enable bit instead of zeroing the entire MSR to make > the code valid for root partition too. > > Signed-off-by: Anirudh Rayabharam <anrayabh@xxxxxxxxxxxxxxxxxxx> > Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx> > Link: https://lore.kernel.org/all/20221027095729.1676394-3-anrayabh@xxxxxxxxxxxxxxxxxxx/ > Signed-off-by: Wei Liu <wei.liu@xxxxxxxxxx> > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> Same with this one -- no stable backports are needed as the patch is more about enabling a new scenario than fixing a bug. Again, Wei Liu or Anirudh should confirm. Michael > --- > arch/x86/hyperv/hv_init.c | 11 +++++++---- > 1 file changed, 7 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c > index 3de6d8b53367..10186bd6d67e 100644 > --- a/arch/x86/hyperv/hv_init.c > +++ b/arch/x86/hyperv/hv_init.c > @@ -537,6 +537,7 @@ void __init hyperv_init(void) > void hyperv_cleanup(void) > { > union hv_x64_msr_hypercall_contents hypercall_msr; > + union hv_reference_tsc_msr tsc_msr; > > unregister_syscore_ops(&hv_syscore_ops); > > @@ -552,12 +553,14 @@ void hyperv_cleanup(void) > hv_hypercall_pg = NULL; > > /* Reset the hypercall page */ > - hypercall_msr.as_uint64 = 0; > - wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); > + hypercall_msr.as_uint64 = hv_get_register(HV_X64_MSR_HYPERCALL); > + hypercall_msr.enable = 0; > + hv_set_register(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); > > /* Reset the TSC page */ > - hypercall_msr.as_uint64 = 0; > - wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64); > + tsc_msr.as_uint64 = hv_get_register(HV_X64_MSR_REFERENCE_TSC); > + tsc_msr.enable = 0; > + hv_set_register(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64); > } > > void hyperv_report_panic(struct pt_regs *regs, long err, bool in_die) > -- > 2.35.1
