BACKPORT: 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: ea7fc1bb1c ("KVM: arm64: Introduce MTE VM feature")
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Reviewed-by: Steven Price <steven.price@arm.com>
[maz: commit message tidy-up]
Signed-off-by: Marc Zyngier <maz@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20221027120945.29679-1-ryan.roberts@arm.com
(cherry picked from commit b6bcdc9f6b8321e4471ff45413b6410e16762a8d)
[willdeacon@: Fixed conflict with aosp/2046214 rework moving MTE feature
 check into caller]
Signed-off-by: Will Deacon <willdeacon@google.com>
Bug: 233587962
Bug: 233588291
Change-Id: Id0aac0fc38dff2569081910af7468ecf97b6eca3

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!
@@ -165,7 +166,8 @@ static void enter_exception64(struct kvm_vcpu *vcpu, unsigned long target_mode,
 	*vcpu_pc(vcpu) = vbar + offset;
 
 	old = *vcpu_cpsr(vcpu);
-	new = get_except64_cpsr(old, kvm_has_mte(vcpu->kvm), sctlr, target_mode);
+	new = get_except64_cpsr(old, kvm_has_mte(kern_hyp_va(vcpu->kvm)), sctlr,
+				target_mode);
 	*vcpu_cpsr(vcpu) = new;
 	__vcpu_write_spsr(vcpu, old);
 }