KVM: arm64: Add sanitisation to SCTLR_EL2

Sanitise SCTLR_EL2 the usual way. The most important aspect of
this is that we benefit from SCTLR_EL2.SPAN being RES1 when
HCR_EL2.E2H==0.

Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Link: https://patch.msgid.link/20260202184329.2724080-20-maz@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>

Author: Marc Zyngier

arch/arm64/include/asm/kvm_host.h

@@ -495,7 +495,6 @@ enum vcpu_sysreg {
 	DBGVCR32_EL2,	/* Debug Vector Catch Register */
 
 	/* EL2 registers */
-	SCTLR_EL2,	/* System Control Register (EL2) */
 	ACTLR_EL2,	/* Auxiliary Control Register (EL2) */
 	CPTR_EL2,	/* Architectural Feature Trap Register (EL2) */
 	HACR_EL2,	/* Hypervisor Auxiliary Control Register */
@@ -526,6 +525,7 @@ enum vcpu_sysreg {
 
 	/* Anything from this can be RES0/RES1 sanitised */
 	MARKER(__SANITISED_REG_START__),
+	SCTLR_EL2,	/* System Control Register (EL2) */
 	TCR2_EL2,	/* Extended Translation Control Register (EL2) */
 	SCTLR2_EL2,	/* System Control Register 2 (EL2) */
 	MDCR_EL2,	/* Monitor Debug Configuration Register (EL2) */

arch/arm64/kvm/config.c

@@ -1123,6 +1123,84 @@ static const struct reg_bits_to_feat_map sctlr_el1_feat_map[] = {
 static const DECLARE_FEAT_MAP(sctlr_el1_desc, SCTLR_EL1,
 			      sctlr_el1_feat_map, FEAT_AA64EL1);
 
+static const struct reg_bits_to_feat_map sctlr_el2_feat_map[] = {
+	NEEDS_FEAT_FLAG(SCTLR_EL2_CP15BEN,
+			RES1_WHEN_E2H0 | REQUIRES_E2H1,
+			FEAT_AA32EL0),
+	NEEDS_FEAT_FLAG(SCTLR_EL2_ITD	|
+			SCTLR_EL2_SED,
+			RES1_WHEN_E2H1 | REQUIRES_E2H1,
+			FEAT_AA32EL0),
+	NEEDS_FEAT_FLAG(SCTLR_EL2_BT0, REQUIRES_E2H1, FEAT_BTI),
+	NEEDS_FEAT(SCTLR_EL2_BT, FEAT_BTI),
+	NEEDS_FEAT_FLAG(SCTLR_EL2_CMOW, REQUIRES_E2H1, FEAT_CMOW),
+	NEEDS_FEAT_FLAG(SCTLR_EL2_TSCXT,
+			RES1_WHEN_E2H1 | REQUIRES_E2H1,
+			feat_csv2_2_csv2_1p2),
+	NEEDS_FEAT_FLAG(SCTLR_EL2_EIS	|
+			SCTLR_EL2_EOS,
+			AS_RES1, FEAT_ExS),
+	NEEDS_FEAT(SCTLR_EL2_EnFPM, FEAT_FPMR),
+	NEEDS_FEAT(SCTLR_EL2_IESB, FEAT_IESB),
+	NEEDS_FEAT_FLAG(SCTLR_EL2_EnALS, REQUIRES_E2H1, FEAT_LS64),
+	NEEDS_FEAT_FLAG(SCTLR_EL2_EnAS0, REQUIRES_E2H1, FEAT_LS64_ACCDATA),
+	NEEDS_FEAT_FLAG(SCTLR_EL2_EnASR, REQUIRES_E2H1, FEAT_LS64_V),
+	NEEDS_FEAT(SCTLR_EL2_nAA, FEAT_LSE2),
+	NEEDS_FEAT_FLAG(SCTLR_EL2_LSMAOE	|
+			SCTLR_EL2_nTLSMD,
+			AS_RES1 | REQUIRES_E2H1, FEAT_LSMAOC),
+	NEEDS_FEAT(SCTLR_EL2_EE, FEAT_MixedEnd),
+	NEEDS_FEAT_FLAG(SCTLR_EL2_E0E, REQUIRES_E2H1, feat_mixedendel0),
+	NEEDS_FEAT_FLAG(SCTLR_EL2_MSCEn, REQUIRES_E2H1, FEAT_MOPS),
+	NEEDS_FEAT_FLAG(SCTLR_EL2_ATA0	|
+			SCTLR_EL2_TCF0,
+			REQUIRES_E2H1, FEAT_MTE2),
+	NEEDS_FEAT(SCTLR_EL2_ATA	|
+		   SCTLR_EL2_TCF,
+		   FEAT_MTE2),
+	NEEDS_FEAT(SCTLR_EL2_ITFSB, feat_mte_async),
+	NEEDS_FEAT_FLAG(SCTLR_EL2_TCSO0, REQUIRES_E2H1, FEAT_MTE_STORE_ONLY),
+	NEEDS_FEAT(SCTLR_EL2_TCSO,
+		   FEAT_MTE_STORE_ONLY),
+	NEEDS_FEAT(SCTLR_EL2_NMI	|
+		   SCTLR_EL2_SPINTMASK,
+		   FEAT_NMI),
+	NEEDS_FEAT_FLAG(SCTLR_EL2_SPAN,	AS_RES1 | REQUIRES_E2H1, FEAT_PAN),
+	NEEDS_FEAT_FLAG(SCTLR_EL2_EPAN, REQUIRES_E2H1, FEAT_PAN3),
+	NEEDS_FEAT(SCTLR_EL2_EnDA	|
+		   SCTLR_EL2_EnDB	|
+		   SCTLR_EL2_EnIA	|
+		   SCTLR_EL2_EnIB,
+		   feat_pauth),
+	NEEDS_FEAT_FLAG(SCTLR_EL2_EnTP2, REQUIRES_E2H1, FEAT_SME),
+	NEEDS_FEAT(SCTLR_EL2_EnRCTX, FEAT_SPECRES),
+	NEEDS_FEAT(SCTLR_EL2_DSSBS, FEAT_SSBS),
+	NEEDS_FEAT_FLAG(SCTLR_EL2_TIDCP, REQUIRES_E2H1, FEAT_TIDCP1),
+	NEEDS_FEAT_FLAG(SCTLR_EL2_TWEDEL	|
+			SCTLR_EL2_TWEDEn,
+			REQUIRES_E2H1, FEAT_TWED),
+	NEEDS_FEAT_FLAG(SCTLR_EL2_nTWE	|
+			SCTLR_EL2_nTWI,
+			AS_RES1 | REQUIRES_E2H1, FEAT_AA64EL2),
+	NEEDS_FEAT_FLAG(SCTLR_EL2_UCI	|
+			SCTLR_EL2_UCT	|
+			SCTLR_EL2_DZE	|
+			SCTLR_EL2_SA0,
+			REQUIRES_E2H1, FEAT_AA64EL2),
+	NEEDS_FEAT(SCTLR_EL2_WXN	|
+		   SCTLR_EL2_I		|
+		   SCTLR_EL2_SA		|
+		   SCTLR_EL2_C		|
+		   SCTLR_EL2_A		|
+		   SCTLR_EL2_M,
+		   FEAT_AA64EL2),
+	FORCE_RES0(SCTLR_EL2_RES0),
+	FORCE_RES1(SCTLR_EL2_RES1),
+};
+
+static const DECLARE_FEAT_MAP(sctlr_el2_desc, SCTLR_EL2,
+			      sctlr_el2_feat_map, FEAT_AA64EL2);
+
 static const struct reg_bits_to_feat_map mdcr_el2_feat_map[] = {
 	NEEDS_FEAT(MDCR_EL2_EBWE, FEAT_Debugv8p9),
 	NEEDS_FEAT(MDCR_EL2_TDOSA, FEAT_DoubleLock),
@@ -1247,6 +1325,7 @@ void __init check_feature_map(void)
 	check_reg_desc(&sctlr2_desc);
 	check_reg_desc(&tcr2_el2_desc);
 	check_reg_desc(&sctlr_el1_desc);
+	check_reg_desc(&sctlr_el2_desc);
 	check_reg_desc(&mdcr_el2_desc);
 	check_reg_desc(&vtcr_el2_desc);
 }
@@ -1443,6 +1522,9 @@ struct resx get_reg_fixed_bits(struct kvm *kvm, enum vcpu_sysreg reg)
 	case SCTLR_EL1:
 		resx = compute_reg_resx_bits(kvm, &sctlr_el1_desc, 0, 0);
 		break;
+	case SCTLR_EL2:
+		resx = compute_reg_resx_bits(kvm, &sctlr_el2_desc, 0, 0);
+		break;
 	case MDCR_EL2:
 		resx = compute_reg_resx_bits(kvm, &mdcr_el2_desc, 0, 0);
 		break;

arch/arm64/kvm/nested.c

@@ -1766,6 +1766,10 @@ int kvm_init_nv_sysregs(struct kvm_vcpu *vcpu)
 	resx = get_reg_fixed_bits(kvm, SCTLR_EL1);
 	set_sysreg_masks(kvm, SCTLR_EL1, resx);
 
+	/* SCTLR_EL2 */
+	resx = get_reg_fixed_bits(kvm, SCTLR_EL2);
+	set_sysreg_masks(kvm, SCTLR_EL2, resx);
+
 	/* SCTLR2_ELx */
 	resx = get_reg_fixed_bits(kvm, SCTLR2_EL1);
 	set_sysreg_masks(kvm, SCTLR2_EL1, resx);