arm64: Prevent kexec and hibernation if is_protected_kvm_enabled()

When pKVM is enabled, the hypervisor code at EL2 and its data structures
are inaccessible to the host kernel and cannot be torn down or replaced
as this would defeat the integrity properies which pKVM aims to provide.
Furthermore, the ABI between the host and EL2 is flexible and private to
whatever the current implementation of KVM requires and so booting a new
kernel with an old EL2 component is very likely to end in disaster.

In preparation for uninstalling the hyp stub calls which are relied upon
to reset EL2, disable kexec and hibernation in the host when protected
KVM is enabled.

Cc: Marc Zyngier <maz@kernel.org>
Cc: Quentin Perret <qperret@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211008135839.1193-3-will@kernel.org

diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 6f6ff072acbde706930cdae2b18fc19be42507bb..44369b99a57ee3f6a118eac09ccac09d144e635f 100644 (file)
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -1128,5 +1128,6 @@ bool cpus_are_stuck_in_kernel(void)
 {
        bool smp_spin_tables = (num_possible_cpus() > 1 && !have_cpu_die());
 
-       return !!cpus_stuck_in_kernel || smp_spin_tables;
+       return !!cpus_stuck_in_kernel || smp_spin_tables ||
+               is_protected_kvm_enabled();
 }