KVM: arm64: Tidying up PAuth code in KVM

Tidy up some of the PAuth trapping code to clear up some comments
and avoid clang/checkpatch warnings. Also, don't bother setting
PAuth HCR_EL2 bits in pKVM, since it's handled by the hypervisor.
Signed-off-by: Fuad Tabba <tabba@google.com>
Link: https://lore.kernel.org/r/20240722163311.1493879-1-tabba@google.comSigned-off-by: Oliver Upton <oliver.upton@linux.dev>

arch/arm64/kvm/arm.c

@@ -522,10 +522,10 @@ void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu)
 
 static void vcpu_set_pauth_traps(struct kvm_vcpu *vcpu)
 {
-	if (vcpu_has_ptrauth(vcpu)) {
+	if (vcpu_has_ptrauth(vcpu) && !is_protected_kvm_enabled()) {
 		/*
-		 * Either we're running running an L2 guest, and the API/APK
-		 * bits come from L1's HCR_EL2, or API/APK are both set.
+		 * Either we're running an L2 guest, and the API/APK bits come
+		 * from L1's HCR_EL2, or API/APK are both set.
 		 */
 		if (unlikely(vcpu_has_nv(vcpu) && !is_hyp_ctxt(vcpu))) {
 			u64 val;
@@ -542,16 +542,10 @@ static void vcpu_set_pauth_traps(struct kvm_vcpu *vcpu)
 		 * Save the host keys if there is any chance for the guest
 		 * to use pauth, as the entry code will reload the guest
 		 * keys in that case.
-		 * Protected mode is the exception to that rule, as the
-		 * entry into the EL2 code eagerly switch back and forth
-		 * between host and hyp keys (and kvm_hyp_ctxt is out of
-		 * reach anyway).
 		 */
-		if (is_protected_kvm_enabled())
-			return;
-
 		if (vcpu->arch.hcr_el2 & (HCR_API | HCR_APK)) {
 			struct kvm_cpu_context *ctxt;
+
 			ctxt = this_cpu_ptr_hyp_sym(kvm_hyp_ctxt);
 			ptrauth_save_keys(ctxt);
 		}

arch/arm64/kvm/hyp/include/hyp/switch.h

@@ -27,7 +27,6 @@
 #include <asm/kvm_hyp.h>
 #include <asm/kvm_mmu.h>
 #include <asm/kvm_nested.h>
-#include <asm/kvm_ptrauth.h>
 #include <asm/fpsimd.h>
 #include <asm/debug-monitors.h>
 #include <asm/processor.h>

arch/arm64/kvm/hyp/nvhe/switch.c

@@ -173,9 +173,8 @@ static void __pmu_switch_to_host(struct kvm_vcpu *vcpu)
 static bool kvm_handle_pvm_sys64(struct kvm_vcpu *vcpu, u64 *exit_code)
 {
 	/*
-	 * Make sure we handle the exit for workarounds and ptrauth
-	 * before the pKVM handling, as the latter could decide to
-	 * UNDEF.
+	 * Make sure we handle the exit for workarounds before the pKVM
+	 * handling, as the latter could decide to UNDEF.
 	 */
 	return (kvm_hyp_handle_sysreg(vcpu, exit_code) ||
 		kvm_handle_pvm_sysreg(vcpu, exit_code));