KVM: arm64: Add REQUIRES_E2H1 constraint as configuration flags

A bunch of EL2 configuration are very similar to their EL1 counterpart,
with the added constraint that HCR_EL2.E2H being 1.

For us, this means HCR_EL2.E2H being RES1, which is something we can
statically evaluate.

Add a REQUIRES_E2H1 constraint, which allows us to express conditions
in a much simpler way (without extra code). Existing occurrences are
converted, before we add a lot more.

Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Link: https://patch.msgid.link/20260202184329.2724080-12-maz@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>

Author: Marc Zyngier

arch/arm64/kvm/config.c

@@ -25,6 +25,7 @@ struct reg_bits_to_feat_map {
 #define	FIXED_VALUE	BIT(2)	/* RAZ/WI or RAO/WI in KVM */
 #define	MASKS_POINTER	BIT(3)	/* Pointer to fgt_masks struct instead of bits */
 #define	AS_RES1		BIT(4)	/* RES1 when not supported */
+#define	REQUIRES_E2H1	BIT(5)	/* Add HCR_EL2.E2H RES1 as a pre-condition */
 
 	unsigned long	flags;
 
@@ -311,21 +312,6 @@ static bool feat_trbe_mpam(struct kvm *kvm)
 		(read_sysreg_s(SYS_TRBIDR_EL1) & TRBIDR_EL1_MPAM));
 }
 
-static bool feat_asid2_e2h1(struct kvm *kvm)
-{
-	return kvm_has_feat(kvm, FEAT_ASID2) && !kvm_has_feat(kvm, FEAT_E2H0);
-}
-
-static bool feat_d128_e2h1(struct kvm *kvm)
-{
-	return kvm_has_feat(kvm, FEAT_D128) && !kvm_has_feat(kvm, FEAT_E2H0);
-}
-
-static bool feat_mec_e2h1(struct kvm *kvm)
-{
-	return kvm_has_feat(kvm, FEAT_MEC) && !kvm_has_feat(kvm, FEAT_E2H0);
-}
-
 static bool feat_ebep_pmuv3_ss(struct kvm *kvm)
 {
 	return kvm_has_feat(kvm, FEAT_EBEP) || kvm_has_feat(kvm, FEAT_PMUv3_SS);
@@ -1045,15 +1031,15 @@ static const DECLARE_FEAT_MAP(sctlr2_desc, SCTLR2_EL1,
 			      sctlr2_feat_map, FEAT_SCTLR2);
 
 static const struct reg_bits_to_feat_map tcr2_el2_feat_map[] = {
-	NEEDS_FEAT(TCR2_EL2_FNG1	|
-		   TCR2_EL2_FNG0	|
-		   TCR2_EL2_A2,
-		   feat_asid2_e2h1),
-	NEEDS_FEAT(TCR2_EL2_DisCH1	|
-		   TCR2_EL2_DisCH0	|
-		   TCR2_EL2_D128,
-		   feat_d128_e2h1),
-	NEEDS_FEAT(TCR2_EL2_AMEC1, feat_mec_e2h1),
+	NEEDS_FEAT_FLAG(TCR2_EL2_FNG1	|
+			TCR2_EL2_FNG0	|
+			TCR2_EL2_A2,
+			REQUIRES_E2H1, FEAT_ASID2),
+	NEEDS_FEAT_FLAG(TCR2_EL2_DisCH1	|
+			TCR2_EL2_DisCH0	|
+			TCR2_EL2_D128,
+			REQUIRES_E2H1, FEAT_D128),
+	NEEDS_FEAT_FLAG(TCR2_EL2_AMEC1, REQUIRES_E2H1, FEAT_MEC),
 	NEEDS_FEAT(TCR2_EL2_AMEC0, FEAT_MEC),
 	NEEDS_FEAT(TCR2_EL2_HAFT, FEAT_HAFT),
 	NEEDS_FEAT(TCR2_EL2_PTTWI	|
@@ -1284,6 +1270,7 @@ static struct resx compute_resx_bits(struct kvm *kvm,
 				     unsigned long require,
 				     unsigned long exclude)
 {
+	bool e2h0 = kvm_has_feat(kvm, FEAT_E2H0);
 	struct resx resx = {};
 
 	for (int i = 0; i < map_size; i++) {
@@ -1306,6 +1293,9 @@ static struct resx compute_resx_bits(struct kvm *kvm,
 			match = idreg_feat_match(kvm, &map[i]);
 		}
 
+		if (map[i].flags & REQUIRES_E2H1)
+			match &= !e2h0;
+
 		if (!match) {
 			if (map[i].flags & AS_RES1)
 				resx.res1 |= reg_feat_map_bits(&map[i]);