KVM: arm64: Fix PAR_EL1.{PTW,S} reporting on AT S1E*

When an AT S1E* operation fails, we need to report whether the
translation failed at S2, and whether this was during a S1 PTW.

But these two bits are not independent. PAR_EL1.PTW can only be
set of PAR_EL1.S is also set, and PAR_EL1.S can only be set on
its own when the full S1 PTW has succeeded, but that the access
itself is reporting a fault at S2.

As a result, it makes no sense to carry both ptw and s2 as parameters
to fail_s1_walk(), and they should be unified.

This fixes a number of cases where we were reporting PTW=1 *and*
S=0, which makes no sense.

Link: https://lore.kernel.org/r/20250422122612.2675672-2-maz@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>

Author: Marc Zyngier

arch/arm64/kvm/at.c

@@ -60,11 +60,11 @@ struct s1_walk_result {
 	bool	failed;
 };
 
-static void fail_s1_walk(struct s1_walk_result *wr, u8 fst, bool ptw, bool s2)
+static void fail_s1_walk(struct s1_walk_result *wr, u8 fst, bool s1ptw)
 {
 	wr->fst		= fst;
-	wr->ptw		= ptw;
-	wr->s2		= s2;
+	wr->ptw		= s1ptw;
+	wr->s2		= s1ptw;
 	wr->failed	= true;
 }
 
@@ -345,11 +345,11 @@ static int setup_s1_walk(struct kvm_vcpu *vcpu, u32 op, struct s1_walk_info *wi,
 	return 0;
 
 addrsz:				/* Address Size Fault level 0 */
-	fail_s1_walk(wr, ESR_ELx_FSC_ADDRSZ_L(0), false, false);
+	fail_s1_walk(wr, ESR_ELx_FSC_ADDRSZ_L(0), false);
 	return -EFAULT;
 
 transfault_l0:			/* Translation Fault level 0 */
-	fail_s1_walk(wr, ESR_ELx_FSC_FAULT_L(0), false, false);
+	fail_s1_walk(wr, ESR_ELx_FSC_FAULT_L(0), false);
 	return -EFAULT;
 }
 
@@ -380,13 +380,13 @@ static int walk_s1(struct kvm_vcpu *vcpu, struct s1_walk_info *wi,
 			if (ret) {
 				fail_s1_walk(wr,
 					     (s2_trans.esr & ~ESR_ELx_FSC_LEVEL) | level,
-					     true, true);
+					     true);
 				return ret;
 			}
 
 			if (!kvm_s2_trans_readable(&s2_trans)) {
 				fail_s1_walk(wr, ESR_ELx_FSC_PERM_L(level),
-					     true, true);
+					     true);
 
 				return -EPERM;
 			}
@@ -396,8 +396,7 @@ static int walk_s1(struct kvm_vcpu *vcpu, struct s1_walk_info *wi,
 
 		ret = kvm_read_guest(vcpu->kvm, ipa, &desc, sizeof(desc));
 		if (ret) {
-			fail_s1_walk(wr, ESR_ELx_FSC_SEA_TTW(level),
-				     true, false);
+			fail_s1_walk(wr, ESR_ELx_FSC_SEA_TTW(level), false);
 			return ret;
 		}
 
@@ -468,10 +467,10 @@ static int walk_s1(struct kvm_vcpu *vcpu, struct s1_walk_info *wi,
 	return 0;
 
 addrsz:
-	fail_s1_walk(wr, ESR_ELx_FSC_ADDRSZ_L(level), true, false);
+	fail_s1_walk(wr, ESR_ELx_FSC_ADDRSZ_L(level), false);
 	return -EINVAL;
 transfault:
-	fail_s1_walk(wr, ESR_ELx_FSC_FAULT_L(level), true, false);
+	fail_s1_walk(wr, ESR_ELx_FSC_FAULT_L(level), false);
 	return -ENOENT;
 }
 
@@ -1198,7 +1197,7 @@ static u64 handle_at_slow(struct kvm_vcpu *vcpu, u32 op, u64 vaddr)
 	}
 
 	if (perm_fail)
-		fail_s1_walk(&wr, ESR_ELx_FSC_PERM_L(wr.level), false, false);
+		fail_s1_walk(&wr, ESR_ELx_FSC_PERM_L(wr.level), false);
 
 compute_par:
 	return compute_par_s1(vcpu, &wr, wi.regime);