[PATCH v4 15/27] KVM: arm64: Support SME control registers

[Mark Brown]

SME is configured by the system registers SMCR_EL1 and SMCR_EL2, add
definitions and userspace access for them.  These control the SME vector
length in a manner similar to that for SVE and also have feature enable
bits for SME2 and FA64.  A subsequent patch will add management of them
for guests as part of the general floating point context switch, as is
done for the equivalent SVE registers.

Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
---
 arch/arm64/include/asm/kvm_host.h     |  2 ++
 arch/arm64/include/asm/vncr_mapping.h |  1 +
 arch/arm64/kvm/sys_regs.c             | 37 ++++++++++++++++++++++++++++++++++-
 3 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 5cc1014120ca6de249093b3e34437a99bc8bf935..f987698f88acf7b01e08e44b46a0982e36cced95 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -485,6 +485,7 @@ enum vcpu_sysreg {
 	CPTR_EL2,	/* Architectural Feature Trap Register (EL2) */
 	HACR_EL2,	/* Hypervisor Auxiliary Control Register */
 	ZCR_EL2,	/* SVE Control Register (EL2) */
+	SMCR_EL2,	/* SME Control Register (EL2) */
 	TTBR0_EL2,	/* Translation Table Base Register 0 (EL2) */
 	TTBR1_EL2,	/* Translation Table Base Register 1 (EL2) */
 	TCR_EL2,	/* Translation Control Register (EL2) */
@@ -522,6 +523,7 @@ enum vcpu_sysreg {
 	VNCR(ACTLR_EL1),/* Auxiliary Control Register */
 	VNCR(CPACR_EL1),/* Coprocessor Access Control */
 	VNCR(ZCR_EL1),	/* SVE Control */
+	VNCR(SMCR_EL1),	/* SME Control */
 	VNCR(TTBR0_EL1),/* Translation Table Base Register 0 */
 	VNCR(TTBR1_EL1),/* Translation Table Base Register 1 */
 	VNCR(TCR_EL1),	/* Translation Control Register */
diff --git a/arch/arm64/include/asm/vncr_mapping.h b/arch/arm64/include/asm/vncr_mapping.h
index 4f9bbd4d6c2671753124599475e5138bf6b9c749..74fc7400efbc7de6b8dd81a485f1e9d545baf7a9 100644
--- a/arch/arm64/include/asm/vncr_mapping.h
+++ b/arch/arm64/include/asm/vncr_mapping.h
@@ -42,6 +42,7 @@
 #define VNCR_HDFGWTR_EL2	0x1D8
 #define VNCR_ZCR_EL1            0x1E0
 #define VNCR_HAFGRTR_EL2	0x1E8
+#define VNCR_SMCR_EL1		0x1F0
 #define VNCR_TTBR0_EL1          0x200
 #define VNCR_TTBR1_EL1          0x210
 #define VNCR_FAR_EL1            0x220
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 49b7844af8a19467e7842347c4b05ceb44c4caaf..597d6a33826d001268d53174581ef8e61e7dd946 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -142,6 +142,7 @@ static bool get_el2_to_el1_mapping(unsigned int reg,
 		MAPPED_EL2_SYSREG(ELR_EL2,     ELR_EL1,	    NULL	     );
 		MAPPED_EL2_SYSREG(SPSR_EL2,    SPSR_EL1,    NULL	     );
 		MAPPED_EL2_SYSREG(ZCR_EL2,     ZCR_EL1,     NULL	     );
+		MAPPED_EL2_SYSREG(SMCR_EL2,    SMCR_EL1,    NULL	     );
 		MAPPED_EL2_SYSREG(CONTEXTIDR_EL2, CONTEXTIDR_EL1, NULL	     );
 	default:
 		return false;
@@ -2429,6 +2430,37 @@ static bool access_zcr_el2(struct kvm_vcpu *vcpu,
 	return true;
 }
 
+static unsigned int sme_el2_visibility(const struct kvm_vcpu *vcpu,
+				       const struct sys_reg_desc *rd)
+{
+	return __el2_visibility(vcpu, rd, sme_visibility);
+}
+
+static bool access_smcr_el2(struct kvm_vcpu *vcpu,
+			    struct sys_reg_params *p,
+			    const struct sys_reg_desc *r)
+{
+	unsigned int vq;
+	u64 smcr;
+
+	if (guest_hyp_sve_traps_enabled(vcpu)) {
+		kvm_inject_nested_sve_trap(vcpu);
+		return true;
+	}
+
+	if (!p->is_write) {
+		p->regval = vcpu_read_sys_reg(vcpu, SMCR_EL2);
+		return true;
+	}
+
+	smcr = p->regval;
+	vq = SYS_FIELD_GET(SMCR_ELx, LEN, smcr) + 1;
+	vq = min(vq, vcpu_sme_max_vq(vcpu));
+	vcpu_write_sys_reg(vcpu, SYS_FIELD_PREP(SMCR_ELx, LEN, vq - 1),
+			   SMCR_EL2);
+	return true;
+}
+
 static unsigned int s1poe_visibility(const struct kvm_vcpu *vcpu,
 				     const struct sys_reg_desc *rd)
 {
@@ -2695,7 +2727,7 @@ static const struct sys_reg_desc sys_reg_descs[] = {
 	{ SYS_DESC(SYS_ZCR_EL1), NULL, reset_val, ZCR_EL1, 0, .visibility = sve_visibility },
 	{ SYS_DESC(SYS_TRFCR_EL1), undef_access },
 	{ SYS_DESC(SYS_SMPRI_EL1), undef_access },
-	{ SYS_DESC(SYS_SMCR_EL1), undef_access },
+	{ SYS_DESC(SYS_SMCR_EL1), NULL, reset_val, SMCR_EL1, 0, .visibility = sme_visibility },
 	{ SYS_DESC(SYS_TTBR0_EL1), access_vm_reg, reset_unknown, TTBR0_EL1 },
 	{ SYS_DESC(SYS_TTBR1_EL1), access_vm_reg, reset_unknown, TTBR1_EL1 },
 	{ SYS_DESC(SYS_TCR_EL1), access_vm_reg, reset_val, TCR_EL1, 0 },
@@ -3047,6 +3079,9 @@ static const struct sys_reg_desc sys_reg_descs[] = {
 
 	EL2_REG_VNCR(HCRX_EL2, reset_val, 0),
 
+	EL2_REG_FILTERED(SMCR_EL2, access_smcr_el2, reset_val, 0,
+			 sme_el2_visibility),
+
 	EL2_REG(TTBR0_EL2, access_rw, reset_val, 0),
 	EL2_REG(TTBR1_EL2, access_rw, reset_val, 0),
 	EL2_REG(TCR_EL2, access_rw, reset_val, TCR_EL2_RES1),

-- 
2.39.5