KVM: arm64: Report faults from S1 walk setup at the expected start level

Translation faults from TTBR must be reported on the start level,
and not level-0. Enforcing this requires moving quite a lot of
code around so that the start level can be computed early enough
that it is usable.

Reviewed-by: Oliver Upton <[email protected]>
Signed-off-by: Marc Zyngier <[email protected]>

Author: Marc Zyngier

arch/arm64/kvm/at.c

@@ -154,9 +154,6 @@ static int setup_s1_walk(struct kvm_vcpu *vcpu, struct s1_walk_info *wi,
 
 	va55 = va & BIT(55);
 
-	if (wi->regime == TR_EL2 && va55)
-		goto addrsz;
-
 	wi->s2 = wi->regime == TR_EL10 && (hcr & (HCR_VM | HCR_DC));
 
 	switch (wi->regime) {
@@ -179,6 +176,46 @@ static int setup_s1_walk(struct kvm_vcpu *vcpu, struct s1_walk_info *wi,
 		BUG();
 	}
 
+	/* Someone was silly enough to encode TG0/TG1 differently */
+	if (va55 && wi->regime != TR_EL2) {
+		wi->txsz = FIELD_GET(TCR_T1SZ_MASK, tcr);
+		tg = FIELD_GET(TCR_TG1_MASK, tcr);
+
+		switch (tg << TCR_TG1_SHIFT) {
+		case TCR_TG1_4K:
+			wi->pgshift = 12;	 break;
+		case TCR_TG1_16K:
+			wi->pgshift = 14;	 break;
+		case TCR_TG1_64K:
+		default:	    /* IMPDEF: treat any other value as 64k */
+			wi->pgshift = 16;	 break;
+		}
+	} else {
+		wi->txsz = FIELD_GET(TCR_T0SZ_MASK, tcr);
+		tg = FIELD_GET(TCR_TG0_MASK, tcr);
+
+		switch (tg << TCR_TG0_SHIFT) {
+		case TCR_TG0_4K:
+			wi->pgshift = 12;	 break;
+		case TCR_TG0_16K:
+			wi->pgshift = 14;	 break;
+		case TCR_TG0_64K:
+		default:	    /* IMPDEF: treat any other value as 64k */
+			wi->pgshift = 16;	 break;
+		}
+	}
+
+	wi->pa52bit = has_52bit_pa(vcpu, wi, tcr);
+
+	ia_bits = get_ia_size(wi);
+
+	/* AArch64.S1StartLevel() */
+	stride = wi->pgshift - 3;
+	wi->sl = 3 - (((ia_bits - 1) - wi->pgshift) / stride);
+
+	if (wi->regime == TR_EL2 && va55)
+		goto addrsz;
+
 	tbi = (wi->regime == TR_EL2 ?
 	       FIELD_GET(TCR_EL2_TBI, tcr) :
 	       (va55 ?
@@ -248,46 +285,15 @@ static int setup_s1_walk(struct kvm_vcpu *vcpu, struct s1_walk_info *wi,
 	/* R_BVXDG */
 	wi->hpd |= (wi->poe || wi->e0poe);
 
-	/* Someone was silly enough to encode TG0/TG1 differently */
-	if (va55) {
-		wi->txsz = FIELD_GET(TCR_T1SZ_MASK, tcr);
-		tg = FIELD_GET(TCR_TG1_MASK, tcr);
-
-		switch (tg << TCR_TG1_SHIFT) {
-		case TCR_TG1_4K:
-			wi->pgshift = 12;	 break;
-		case TCR_TG1_16K:
-			wi->pgshift = 14;	 break;
-		case TCR_TG1_64K:
-		default:	    /* IMPDEF: treat any other value as 64k */
-			wi->pgshift = 16;	 break;
-		}
-	} else {
-		wi->txsz = FIELD_GET(TCR_T0SZ_MASK, tcr);
-		tg = FIELD_GET(TCR_TG0_MASK, tcr);
-
-		switch (tg << TCR_TG0_SHIFT) {
-		case TCR_TG0_4K:
-			wi->pgshift = 12;	 break;
-		case TCR_TG0_16K:
-			wi->pgshift = 14;	 break;
-		case TCR_TG0_64K:
-		default:	    /* IMPDEF: treat any other value as 64k */
-			wi->pgshift = 16;	 break;
-		}
-	}
-
 	/* R_PLCGL, R_YXNYW */
 	if (!kvm_has_feat_enum(vcpu->kvm, ID_AA64MMFR2_EL1, ST, 48_47)) {
 		if (wi->txsz > 39)
-			goto transfault_l0;
+			goto transfault;
 	} else {
 		if (wi->txsz > 48 || (BIT(wi->pgshift) == SZ_64K && wi->txsz > 47))
-			goto transfault_l0;
+			goto transfault;
 	}
 
-	wi->pa52bit = has_52bit_pa(vcpu, wi, tcr);
-
 	/* R_GTJBY, R_SXWGM */
 	switch (BIT(wi->pgshift)) {
 	case SZ_4K:
@@ -300,28 +306,22 @@ static int setup_s1_walk(struct kvm_vcpu *vcpu, struct s1_walk_info *wi,
 	}
 
 	if ((lva && wi->txsz < 12) || (!lva && wi->txsz < 16))
-		goto transfault_l0;
-
-	ia_bits = get_ia_size(wi);
+		goto transfault;
 
 	/* R_YYVYV, I_THCZK */
 	if ((!va55 && va > GENMASK(ia_bits - 1, 0)) ||
 	    (va55 && va < GENMASK(63, ia_bits)))
-		goto transfault_l0;
+		goto transfault;
 
 	/* I_ZFSYQ */
 	if (wi->regime != TR_EL2 &&
 	    (tcr & (va55 ? TCR_EPD1_MASK : TCR_EPD0_MASK)))
-		goto transfault_l0;
+		goto transfault;
 
 	/* R_BNDVG and following statements */
 	if (kvm_has_feat(vcpu->kvm, ID_AA64MMFR2_EL1, E0PD, IMP) &&
 	    wi->as_el0 && (tcr & (va55 ? TCR_E0PD1 : TCR_E0PD0)))
-		goto transfault_l0;
-
-	/* AArch64.S1StartLevel() */
-	stride = wi->pgshift - 3;
-	wi->sl = 3 - (((ia_bits - 1) - wi->pgshift) / stride);
+		goto transfault;
 
 	ps = (wi->regime == TR_EL2 ?
 	      FIELD_GET(TCR_EL2_PS_MASK, tcr) : FIELD_GET(TCR_IPS_MASK, tcr));
@@ -351,12 +351,17 @@ static int setup_s1_walk(struct kvm_vcpu *vcpu, struct s1_walk_info *wi,
 
 	return 0;
 
-addrsz:				/* Address Size Fault level 0 */
+addrsz:
+	/*
+	 * Address Size Fault level 0 to indicate it comes from TTBR.
+	 * yes, this is an oddity.
+	 */
 	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);
+transfault:
+	/* Translation Fault on start level */
+	fail_s1_walk(wr, ESR_ELx_FSC_FAULT_L(wi->sl), false);
 	return -EFAULT;
 }