KVM: arm64: Fix EL2 mode availability checks

With protected nVHE hyp code interception host's PSCI SMCs, the host
starts seeing new CPUs boot in EL1 instead of EL2. The kernel logic
that keeps track of the boot mode needs to be adjusted.

Add a static key enabled if KVM protected mode initialization is
successful.

When the key is enabled, is_hyp_mode_available continues to report
`true` because its users either treat it as a check whether KVM will be
/ was initialized, or whether stub HVCs can be made (eg. hibernate).

is_hyp_mode_mismatched is changed to report `false` when the key is
enabled. That's because all cores' modes matched at the point of KVM
init and KVM will not allow cores not present at init to boot. That
said, the function is never used after KVM is initialized.

Signed-off-by: David Brazdil <dbrazdil@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20201202184122.26046-27-dbrazdil@google.com

1 files changed, 6 insertions, 3 deletions

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 7d162a296141..fadcc94931f9 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -48,6 +48,7 @@ __asm__(".arch_extension	virt");
 #endif
 
 static enum kvm_mode kvm_mode = KVM_MODE_DEFAULT;
+DEFINE_STATIC_KEY_FALSE(kvm_protected_mode_initialized);
 
 DECLARE_KVM_HYP_PER_CPU(unsigned long, kvm_hyp_vector);
 
@@ -1848,12 +1849,14 @@ int kvm_arch_init(void *opaque)
 	if (err)
 		goto out_hyp;
 
-	if (is_protected_kvm_enabled())
+	if (is_protected_kvm_enabled()) {
+		static_branch_enable(&kvm_protected_mode_initialized);
 		kvm_info("Protected nVHE mode initialized successfully\n");
-	else if (in_hyp_mode)
+	} else if (in_hyp_mode) {
 		kvm_info("VHE mode initialized successfully\n");
-	else
+	} else {
 		kvm_info("Hyp mode initialized successfully\n");
+	}
 
 	return 0;