arm64: KVM: Add ARCH_WORKAROUND_2 support for guests

commit 55e3748e8902ff641e334226bdcb432f9a5d78d3 upstream.

In order to offer ARCH_WORKAROUND_2 support to guests, we need
a bit of infrastructure.

Let's add a flag indicating whether or not the guest uses
SSBD mitigation. Depending on the state of this flag, allow
KVM to disable ARCH_WORKAROUND_2 before entering the guest,
and enable it when exiting it.

Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index d7cd541..2043697 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -1367,6 +1367,12 @@ static int init_hyp_mode(void)
 		}
 	}
 
+	err = hyp_map_aux_data();
+	if (err) {
+		kvm_err("Cannot map host auxilary data: %d\n", err);
+		goto out_err;
+	}
+
 	kvm_info("Hyp mode initialized successfully\n");
 
 	return 0;