KVM: arm64: Fix bad dereference on MTE-enabled systems

enter_exception64() performs an MTE check, which involves dereferencing
vcpu->kvm. While vcpu has already been fixed up to be a HYP VA pointer,
kvm is still a pointer in the kernel VA space.

This only affects nVHE configurations with MTE enabled, as in other
cases, the pointer is either valid (VHE) or not dereferenced (!MTE).

Fix this by first converting kvm to a HYP VA pointer.

Fixes: ea7fc1b ("KVM: arm64: Introduce MTE VM feature")
Signed-off-by: Ryan Roberts <[email protected]>
Reviewed-by: Steven Price <[email protected]>
[maz: commit message tidy-up]
Signed-off-by: Marc Zyngier <[email protected]>
Cc: [email protected]
Link: https://lore.kernel.org/r/[email protected]

Author: Ryan Roberts

arch/arm64/kvm/hyp/exception.c

@@ -13,6 +13,7 @@
 #include <hyp/adjust_pc.h>
 #include <linux/kvm_host.h>
 #include <asm/kvm_emulate.h>
+#include <asm/kvm_mmu.h>
 
 #if !defined (__KVM_NVHE_HYPERVISOR__) && !defined (__KVM_VHE_HYPERVISOR__)
 #error Hypervisor code only!
@@ -115,7 +116,7 @@ static void enter_exception64(struct kvm_vcpu *vcpu, unsigned long target_mode,
 	new |= (old & PSR_C_BIT);
 	new |= (old & PSR_V_BIT);
 
-	if (kvm_has_mte(vcpu->kvm))
+	if (kvm_has_mte(kern_hyp_va(vcpu->kvm)))
 		new |= PSR_TCO_BIT;
 
 	new |= (old & PSR_DIT_BIT);