KVM: arm/arm64: vgic: Implement VGICv3 CPU interface access

VGICv3 CPU interface registers are accessed using
KVM_DEV_ARM_VGIC_CPU_SYSREGS ioctl. These registers are accessed
as 64-bit. The cpu MPIDR value is passed along with register id.
It is used to identify the cpu for registers access.

The VM that supports SEIs expect it on destination machine to handle
guest aborts and hence checked for ICC_CTLR_EL1.SEIS compatibility.
Similarly, VM that supports Affinity Level 3 that is required for AArch64
mode, is required to be supported on destination machine. Hence checked
for ICC_CTLR_EL1.A3V compatibility.

The arch/arm64/kvm/vgic-sys-reg-v3.c handles read and write of VGIC
CPU registers for AArch64.

For AArch32 mode, arch/arm/kvm/vgic-v3-coproc.c file is created but
APIs are not implemented.

Updated arch/arm/include/uapi/asm/kvm.h with new definitions
required to compile for AArch32.

The version of VGIC v3 specification is defined here
Documentation/virtual/kvm/devices/arm-vgic-v3.txt

Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Pavel Fedin <p.fedin@samsung.com>
Signed-off-by: Vijaya Kumar K <Vijaya.Kumar@cavium.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

arch/arm/include/uapi/asm/kvm.h

@@ -186,9 +186,12 @@ struct kvm_arch_memory_slot {
 			(0xffffffffULL << KVM_DEV_ARM_VGIC_V3_MPIDR_SHIFT)
 #define   KVM_DEV_ARM_VGIC_OFFSET_SHIFT	0
 #define   KVM_DEV_ARM_VGIC_OFFSET_MASK	(0xffffffffULL << KVM_DEV_ARM_VGIC_OFFSET_SHIFT)
+#define   KVM_DEV_ARM_VGIC_SYSREG_INSTR_MASK (0xffff)
 #define KVM_DEV_ARM_VGIC_GRP_NR_IRQS	3
 #define KVM_DEV_ARM_VGIC_GRP_CTRL       4
 #define KVM_DEV_ARM_VGIC_GRP_REDIST_REGS 5
+#define KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS 6
+
 #define   KVM_DEV_ARM_VGIC_CTRL_INIT    0
 
 /* KVM_IRQ_LINE irq field index values */

arch/arm/kvm/Makefile

@@ -7,7 +7,7 @@ ifeq ($(plus_virt),+virt)
 	plus_virt_def := -DREQUIRES_VIRT=1
 endif
 
-ccflags-y += -Iarch/arm/kvm
+ccflags-y += -Iarch/arm/kvm -Ivirt/kvm/arm/vgic
 CFLAGS_arm.o := -I. $(plus_virt_def)
 CFLAGS_mmu.o := -I.
 
@@ -20,7 +20,7 @@ kvm-arm-y = $(KVM)/kvm_main.o $(KVM)/coalesced_mmio.o $(KVM)/eventfd.o $(KVM)/vf
 obj-$(CONFIG_KVM_ARM_HOST) += hyp/
 obj-y += kvm-arm.o init.o interrupts.o
 obj-y += arm.o handle_exit.o guest.o mmu.o emulate.o reset.o
-obj-y += coproc.o coproc_a15.o coproc_a7.o mmio.o psci.o perf.o
+obj-y += coproc.o coproc_a15.o coproc_a7.o mmio.o psci.o perf.o vgic-v3-coproc.o
 obj-y += $(KVM)/arm/aarch32.o
 
 obj-y += $(KVM)/arm/vgic/vgic.o

arch/arm/kvm/vgic-v3-coproc.c

@@ -0,0 +1,35 @@
+/*
+ * VGIC system registers handling functions for AArch32 mode
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/kvm.h>
+#include <linux/kvm_host.h>
+#include <asm/kvm_emulate.h>
+#include "vgic.h"
+
+int vgic_v3_has_cpu_sysregs_attr(struct kvm_vcpu *vcpu, bool is_write, u64 id,
+				 u64 *reg)
+{
+	/*
+	 * TODO: Implement for AArch32
+	 */
+	return -ENXIO;
+}
+
+int vgic_v3_cpu_sysregs_uaccess(struct kvm_vcpu *vcpu, bool is_write, u64 id,
+				u64 *reg)
+{
+	/*
+	 * TODO: Implement for AArch32
+	 */
+	return -ENXIO;
+}

arch/arm64/include/uapi/asm/kvm.h

@@ -206,9 +206,12 @@ struct kvm_arch_memory_slot {
 			(0xffffffffULL << KVM_DEV_ARM_VGIC_V3_MPIDR_SHIFT)
 #define   KVM_DEV_ARM_VGIC_OFFSET_SHIFT	0
 #define   KVM_DEV_ARM_VGIC_OFFSET_MASK	(0xffffffffULL << KVM_DEV_ARM_VGIC_OFFSET_SHIFT)
+#define   KVM_DEV_ARM_VGIC_SYSREG_INSTR_MASK (0xffff)
 #define KVM_DEV_ARM_VGIC_GRP_NR_IRQS	3
 #define KVM_DEV_ARM_VGIC_GRP_CTRL	4
 #define KVM_DEV_ARM_VGIC_GRP_REDIST_REGS 5
+#define KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS 6
+
 #define   KVM_DEV_ARM_VGIC_CTRL_INIT	0
 
 /* Device Control API on vcpu fd */

arch/arm64/kvm/Makefile

@@ -2,7 +2,7 @@
 # Makefile for Kernel-based Virtual Machine module
 #
 
-ccflags-y += -Iarch/arm64/kvm
+ccflags-y += -Iarch/arm64/kvm -Ivirt/kvm/arm/vgic
 CFLAGS_arm.o := -I.
 CFLAGS_mmu.o := -I.
 
@@ -19,6 +19,7 @@ kvm-$(CONFIG_KVM_ARM_HOST) += $(ARM)/psci.o $(ARM)/perf.o
 kvm-$(CONFIG_KVM_ARM_HOST) += inject_fault.o regmap.o
 kvm-$(CONFIG_KVM_ARM_HOST) += hyp.o hyp-init.o handle_exit.o
 kvm-$(CONFIG_KVM_ARM_HOST) += guest.o debug.o reset.o sys_regs.o sys_regs_generic_v8.o
+kvm-$(CONFIG_KVM_ARM_HOST) += vgic-sys-reg-v3.o
 kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/aarch32.o
 
 kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/vgic/vgic.o

arch/arm64/kvm/vgic-sys-reg-v3.c

@@ -0,0 +1,346 @@
+/*
+ * VGIC system registers handling functions for AArch64 mode
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/irqchip/arm-gic-v3.h>
+#include <linux/kvm.h>
+#include <linux/kvm_host.h>
+#include <asm/kvm_emulate.h>
+#include "vgic.h"
+#include "sys_regs.h"
+
+static bool access_gic_ctlr(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
+			    const struct sys_reg_desc *r)
+{
+	u32 host_pri_bits, host_id_bits, host_seis, host_a3v, seis, a3v;
+	struct vgic_cpu *vgic_v3_cpu = &vcpu->arch.vgic_cpu;
+	struct vgic_vmcr vmcr;
+	u64 val;
+
+	vgic_get_vmcr(vcpu, &vmcr);
+	if (p->is_write) {
+		val = p->regval;
+
+		/*
+		 * Disallow restoring VM state if not supported by this
+		 * hardware.
+		 */
+		host_pri_bits = ((val & ICC_CTLR_EL1_PRI_BITS_MASK) >>
+				 ICC_CTLR_EL1_PRI_BITS_SHIFT) + 1;
+		if (host_pri_bits > vgic_v3_cpu->num_pri_bits)
+			return false;
+
+		vgic_v3_cpu->num_pri_bits = host_pri_bits;
+
+		host_id_bits = (val & ICC_CTLR_EL1_ID_BITS_MASK) >>
+				ICC_CTLR_EL1_ID_BITS_SHIFT;
+		if (host_id_bits > vgic_v3_cpu->num_id_bits)
+			return false;
+
+		vgic_v3_cpu->num_id_bits = host_id_bits;
+
+		host_seis = ((kvm_vgic_global_state.ich_vtr_el2 &
+			     ICH_VTR_SEIS_MASK) >> ICH_VTR_SEIS_SHIFT);
+		seis = (val & ICC_CTLR_EL1_SEIS_MASK) >>
+			ICC_CTLR_EL1_SEIS_SHIFT;
+		if (host_seis != seis)
+			return false;
+
+		host_a3v = ((kvm_vgic_global_state.ich_vtr_el2 &
+			    ICH_VTR_A3V_MASK) >> ICH_VTR_A3V_SHIFT);
+		a3v = (val & ICC_CTLR_EL1_A3V_MASK) >> ICC_CTLR_EL1_A3V_SHIFT;
+		if (host_a3v != a3v)
+			return false;
+
+		/*
+		 * Here set VMCR.CTLR in ICC_CTLR_EL1 layout.
+		 * The vgic_set_vmcr() will convert to ICH_VMCR layout.
+		 */
+		vmcr.ctlr = val & ICC_CTLR_EL1_CBPR_MASK;
+		vmcr.ctlr |= val & ICC_CTLR_EL1_EOImode_MASK;
+		vgic_set_vmcr(vcpu, &vmcr);
+	} else {
+		val = 0;
+		val |= (vgic_v3_cpu->num_pri_bits - 1) <<
+			ICC_CTLR_EL1_PRI_BITS_SHIFT;
+		val |= vgic_v3_cpu->num_id_bits << ICC_CTLR_EL1_ID_BITS_SHIFT;
+		val |= ((kvm_vgic_global_state.ich_vtr_el2 &
+			ICH_VTR_SEIS_MASK) >> ICH_VTR_SEIS_SHIFT) <<
+			ICC_CTLR_EL1_SEIS_SHIFT;
+		val |= ((kvm_vgic_global_state.ich_vtr_el2 &
+			ICH_VTR_A3V_MASK) >> ICH_VTR_A3V_SHIFT) <<
+			ICC_CTLR_EL1_A3V_SHIFT;
+		/*
+		 * The VMCR.CTLR value is in ICC_CTLR_EL1 layout.
+		 * Extract it directly using ICC_CTLR_EL1 reg definitions.
+		 */
+		val |= vmcr.ctlr & ICC_CTLR_EL1_CBPR_MASK;
+		val |= vmcr.ctlr & ICC_CTLR_EL1_EOImode_MASK;
+
+		p->regval = val;
+	}
+
+	return true;
+}
+
+static bool access_gic_pmr(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
+			   const struct sys_reg_desc *r)
+{
+	struct vgic_vmcr vmcr;
+
+	vgic_get_vmcr(vcpu, &vmcr);
+	if (p->is_write) {
+		vmcr.pmr = (p->regval & ICC_PMR_EL1_MASK) >> ICC_PMR_EL1_SHIFT;
+		vgic_set_vmcr(vcpu, &vmcr);
+	} else {
+		p->regval = (vmcr.pmr << ICC_PMR_EL1_SHIFT) & ICC_PMR_EL1_MASK;
+	}
+
+	return true;
+}
+
+static bool access_gic_bpr0(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
+			    const struct sys_reg_desc *r)
+{
+	struct vgic_vmcr vmcr;
+
+	vgic_get_vmcr(vcpu, &vmcr);
+	if (p->is_write) {
+		vmcr.bpr = (p->regval & ICC_BPR0_EL1_MASK) >>
+			    ICC_BPR0_EL1_SHIFT;
+		vgic_set_vmcr(vcpu, &vmcr);
+	} else {
+		p->regval = (vmcr.bpr << ICC_BPR0_EL1_SHIFT) &
+			     ICC_BPR0_EL1_MASK;
+	}
+
+	return true;
+}
+
+static bool access_gic_bpr1(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
+			    const struct sys_reg_desc *r)
+{
+	struct vgic_vmcr vmcr;
+
+	if (!p->is_write)
+		p->regval = 0;
+
+	vgic_get_vmcr(vcpu, &vmcr);
+	if (!((vmcr.ctlr & ICH_VMCR_CBPR_MASK) >> ICH_VMCR_CBPR_SHIFT)) {
+		if (p->is_write) {
+			vmcr.abpr = (p->regval & ICC_BPR1_EL1_MASK) >>
+				     ICC_BPR1_EL1_SHIFT;
+			vgic_set_vmcr(vcpu, &vmcr);
+		} else {
+			p->regval = (vmcr.abpr << ICC_BPR1_EL1_SHIFT) &
+				     ICC_BPR1_EL1_MASK;
+		}
+	} else {
+		if (!p->is_write)
+			p->regval = min((vmcr.bpr + 1), 7U);
+	}
+
+	return true;
+}
+
+static bool access_gic_grpen0(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
+			      const struct sys_reg_desc *r)
+{
+	struct vgic_vmcr vmcr;
+
+	vgic_get_vmcr(vcpu, &vmcr);
+	if (p->is_write) {
+		vmcr.grpen0 = (p->regval & ICC_IGRPEN0_EL1_MASK) >>
+			       ICC_IGRPEN0_EL1_SHIFT;
+		vgic_set_vmcr(vcpu, &vmcr);
+	} else {
+		p->regval = (vmcr.grpen0 << ICC_IGRPEN0_EL1_SHIFT) &
+			     ICC_IGRPEN0_EL1_MASK;
+	}
+
+	return true;
+}
+
+static bool access_gic_grpen1(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
+			      const struct sys_reg_desc *r)
+{
+	struct vgic_vmcr vmcr;
+
+	vgic_get_vmcr(vcpu, &vmcr);
+	if (p->is_write) {
+		vmcr.grpen1 = (p->regval & ICC_IGRPEN1_EL1_MASK) >>
+			       ICC_IGRPEN1_EL1_SHIFT;
+		vgic_set_vmcr(vcpu, &vmcr);
+	} else {
+		p->regval = (vmcr.grpen1 << ICC_IGRPEN1_EL1_SHIFT) &
+			     ICC_IGRPEN1_EL1_MASK;
+	}
+
+	return true;
+}
+
+static void vgic_v3_access_apr_reg(struct kvm_vcpu *vcpu,
+				   struct sys_reg_params *p, u8 apr, u8 idx)
+{
+	struct vgic_v3_cpu_if *vgicv3 = &vcpu->arch.vgic_cpu.vgic_v3;
+	uint32_t *ap_reg;
+
+	if (apr)
+		ap_reg = &vgicv3->vgic_ap1r[idx];
+	else
+		ap_reg = &vgicv3->vgic_ap0r[idx];
+
+	if (p->is_write)
+		*ap_reg = p->regval;
+	else
+		p->regval = *ap_reg;
+}
+
+static bool access_gic_aprn(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
+			    const struct sys_reg_desc *r, u8 apr)
+{
+	struct vgic_cpu *vgic_v3_cpu = &vcpu->arch.vgic_cpu;
+	u8 idx = r->Op2 & 3;
+
+	/*
+	 * num_pri_bits are initialized with HW supported values.
+	 * We can rely safely on num_pri_bits even if VM has not
+	 * restored ICC_CTLR_EL1 before restoring APnR registers.
+	 */
+	switch (vgic_v3_cpu->num_pri_bits) {
+	case 7:
+		vgic_v3_access_apr_reg(vcpu, p, apr, idx);
+		break;
+	case 6:
+		if (idx > 1)
+			goto err;
+		vgic_v3_access_apr_reg(vcpu, p, apr, idx);
+		break;
+	default:
+		if (idx > 0)
+			goto err;
+		vgic_v3_access_apr_reg(vcpu, p, apr, idx);
+	}
+
+	return true;
+err:
+	if (!p->is_write)
+		p->regval = 0;
+
+	return false;
+}
+
+static bool access_gic_ap0r(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
+			    const struct sys_reg_desc *r)
+
+{
+	return access_gic_aprn(vcpu, p, r, 0);
+}
+
+static bool access_gic_ap1r(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
+			    const struct sys_reg_desc *r)
+{
+	return access_gic_aprn(vcpu, p, r, 1);
+}
+
+static bool access_gic_sre(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
+			   const struct sys_reg_desc *r)
+{
+	struct vgic_v3_cpu_if *vgicv3 = &vcpu->arch.vgic_cpu.vgic_v3;
+
+	/* Validate SRE bit */
+	if (p->is_write) {
+		if (!(p->regval & ICC_SRE_EL1_SRE))
+			return false;
+	} else {
+		p->regval = vgicv3->vgic_sre;
+	}
+
+	return true;
+}
+static const struct sys_reg_desc gic_v3_icc_reg_descs[] = {
+	/* ICC_PMR_EL1 */
+	{ Op0(3), Op1(0), CRn(4), CRm(6), Op2(0), access_gic_pmr },
+	/* ICC_BPR0_EL1 */
+	{ Op0(3), Op1(0), CRn(12), CRm(8), Op2(3), access_gic_bpr0 },
+	/* ICC_AP0R0_EL1 */
+	{ Op0(3), Op1(0), CRn(12), CRm(8), Op2(4), access_gic_ap0r },
+	/* ICC_AP0R1_EL1 */
+	{ Op0(3), Op1(0), CRn(12), CRm(8), Op2(5), access_gic_ap0r },
+	/* ICC_AP0R2_EL1 */
+	{ Op0(3), Op1(0), CRn(12), CRm(8), Op2(6), access_gic_ap0r },
+	/* ICC_AP0R3_EL1 */
+	{ Op0(3), Op1(0), CRn(12), CRm(8), Op2(7), access_gic_ap0r },
+	/* ICC_AP1R0_EL1 */
+	{ Op0(3), Op1(0), CRn(12), CRm(9), Op2(0), access_gic_ap1r },
+	/* ICC_AP1R1_EL1 */
+	{ Op0(3), Op1(0), CRn(12), CRm(9), Op2(1), access_gic_ap1r },
+	/* ICC_AP1R2_EL1 */
+	{ Op0(3), Op1(0), CRn(12), CRm(9), Op2(2), access_gic_ap1r },
+	/* ICC_AP1R3_EL1 */
+	{ Op0(3), Op1(0), CRn(12), CRm(9), Op2(3), access_gic_ap1r },
+	/* ICC_BPR1_EL1 */
+	{ Op0(3), Op1(0), CRn(12), CRm(12), Op2(3), access_gic_bpr1 },
+	/* ICC_CTLR_EL1 */
+	{ Op0(3), Op1(0), CRn(12), CRm(12), Op2(4), access_gic_ctlr },
+	/* ICC_SRE_EL1 */
+	{ Op0(3), Op1(0), CRn(12), CRm(12), Op2(5), access_gic_sre },
+	/* ICC_IGRPEN0_EL1 */
+	{ Op0(3), Op1(0), CRn(12), CRm(12), Op2(6), access_gic_grpen0 },
+	/* ICC_GRPEN1_EL1 */
+	{ Op0(3), Op1(0), CRn(12), CRm(12), Op2(7), access_gic_grpen1 },
+};
+
+int vgic_v3_has_cpu_sysregs_attr(struct kvm_vcpu *vcpu, bool is_write, u64 id,
+				u64 *reg)
+{
+	struct sys_reg_params params;
+	u64 sysreg = (id & KVM_DEV_ARM_VGIC_SYSREG_MASK) | KVM_REG_SIZE_U64;
+
+	params.regval = *reg;
+	params.is_write = is_write;
+	params.is_aarch32 = false;
+	params.is_32bit = false;
+
+	if (find_reg_by_id(sysreg, &params, gic_v3_icc_reg_descs,
+			      ARRAY_SIZE(gic_v3_icc_reg_descs)))
+		return 0;
+
+	return -ENXIO;
+}
+
+int vgic_v3_cpu_sysregs_uaccess(struct kvm_vcpu *vcpu, bool is_write, u64 id,
+				u64 *reg)
+{
+	struct sys_reg_params params;
+	const struct sys_reg_desc *r;
+	u64 sysreg = (id & KVM_DEV_ARM_VGIC_SYSREG_MASK) | KVM_REG_SIZE_U64;
+
+	if (is_write)
+		params.regval = *reg;
+	params.is_write = is_write;
+	params.is_aarch32 = false;
+	params.is_32bit = false;
+
+	r = find_reg_by_id(sysreg, &params, gic_v3_icc_reg_descs,
+			   ARRAY_SIZE(gic_v3_icc_reg_descs));
+	if (!r)
+		return -ENXIO;
+
+	if (!r->access(vcpu, &params, r))
+		return -EINVAL;
+
+	if (!is_write)
+		*reg = params.regval;
+
+	return 0;
+}

include/kvm/arm_vgic.h

@@ -71,6 +71,8 @@ struct vgic_global {
 
 	/* GIC system register CPU interface */
 	struct static_key_false gicv3_cpuif;
+
+	u32			ich_vtr_el2;
 };
 
 extern struct vgic_global kvm_vgic_global_state;
@@ -275,6 +277,12 @@ struct vgic_cpu {
 	u64 pendbaser;
 
 	bool lpis_enabled;
+
+	/* Cache guest priority bits */
+	u32 num_pri_bits;
+
+	/* Cache guest interrupt ID bits */
+	u32 num_id_bits;
 };
 
 extern struct static_key_false vgic_v2_cpuif_trap;

virt/kvm/arm/vgic/vgic-kvm-device.c

@@ -504,6 +504,14 @@ static int vgic_v3_attr_regs_access(struct kvm_device *dev,
 		if (!is_write)
 			*reg = tmp32;
 		break;
+	case KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS: {
+		u64 regid;
+
+		regid = (attr->attr & KVM_DEV_ARM_VGIC_SYSREG_INSTR_MASK);
+		ret = vgic_v3_cpu_sysregs_uaccess(vcpu, is_write,
+						  regid, reg);
+		break;
+	}
 	default:
 		ret = -EINVAL;
 		break;
@@ -537,6 +545,15 @@ static int vgic_v3_set_attr(struct kvm_device *dev,
 		reg = tmp32;
 		return vgic_v3_attr_regs_access(dev, attr, &reg, true);
 	}
+	case KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS: {
+		u64 __user *uaddr = (u64 __user *)(long)attr->addr;
+		u64 reg;
+
+		if (get_user(reg, uaddr))
+			return -EFAULT;
+
+		return vgic_v3_attr_regs_access(dev, attr, &reg, true);
+	}
 	}
 	return -ENXIO;
 }
@@ -563,6 +580,15 @@ static int vgic_v3_get_attr(struct kvm_device *dev,
 		tmp32 = reg;
 		return put_user(tmp32, uaddr);
 	}
+	case KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS: {
+		u64 __user *uaddr = (u64 __user *)(long)attr->addr;
+		u64 reg;
+
+		ret = vgic_v3_attr_regs_access(dev, attr, &reg, false);
+		if (ret)
+			return ret;
+		return put_user(reg, uaddr);
+	}
 	}
 
 	return -ENXIO;
@@ -581,6 +607,7 @@ static int vgic_v3_has_attr(struct kvm_device *dev,
 		break;
 	case KVM_DEV_ARM_VGIC_GRP_DIST_REGS:
 	case KVM_DEV_ARM_VGIC_GRP_REDIST_REGS:
+	case KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS:
 		return vgic_v3_has_attr_regs(dev, attr);
 	case KVM_DEV_ARM_VGIC_GRP_NR_IRQS:
 		return 0;

virt/kvm/arm/vgic/vgic-mmio-v3.c

@@ -645,6 +645,12 @@ int vgic_v3_has_attr_regs(struct kvm_device *dev, struct kvm_device_attr *attr)
 		iodev.base_addr = 0;
 		break;
 	}
+	case KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS: {
+		u64 reg, id;
+
+		id = (attr->attr & KVM_DEV_ARM_VGIC_SYSREG_INSTR_MASK);
+		return vgic_v3_has_cpu_sysregs_attr(vcpu, 0, id, &reg);
+	}
 	default:
 		return -ENXIO;
 	}

virt/kvm/arm/vgic/vgic-v3.c

@@ -238,6 +238,13 @@ void vgic_v3_enable(struct kvm_vcpu *vcpu)
 		vgic_v3->vgic_sre = 0;
 	}
 
+	vcpu->arch.vgic_cpu.num_id_bits = (kvm_vgic_global_state.ich_vtr_el2 &
+					   ICH_VTR_ID_BITS_MASK) >>
+					   ICH_VTR_ID_BITS_SHIFT;
+	vcpu->arch.vgic_cpu.num_pri_bits = ((kvm_vgic_global_state.ich_vtr_el2 &
+					    ICH_VTR_PRI_BITS_MASK) >>
+					    ICH_VTR_PRI_BITS_SHIFT) + 1;
+
 	/* Get the show on the road... */
 	vgic_v3->vgic_hcr = ICH_HCR_EN;
 }
@@ -336,6 +343,7 @@ int vgic_v3_probe(const struct gic_kvm_info *info)
 	 */
 	kvm_vgic_global_state.nr_lr = (ich_vtr_el2 & 0xf) + 1;
 	kvm_vgic_global_state.can_emulate_gicv2 = false;
+	kvm_vgic_global_state.ich_vtr_el2 = ich_vtr_el2;
 
 	if (!info->vcpu.start) {
 		kvm_info("GICv3: no GICV resource entry\n");

virt/kvm/arm/vgic/vgic.h

@@ -52,6 +52,27 @@
 			    VGIC_AFFINITY_LEVEL(val, 2) | \
 			    VGIC_AFFINITY_LEVEL(val, 3))
 
+/*
+ * As per Documentation/virtual/kvm/devices/arm-vgic-v3.txt,
+ * below macros are defined for CPUREG encoding.
+ */
+#define KVM_REG_ARM_VGIC_SYSREG_OP0_MASK   0x000000000000c000
+#define KVM_REG_ARM_VGIC_SYSREG_OP0_SHIFT  14
+#define KVM_REG_ARM_VGIC_SYSREG_OP1_MASK   0x0000000000003800
+#define KVM_REG_ARM_VGIC_SYSREG_OP1_SHIFT  11
+#define KVM_REG_ARM_VGIC_SYSREG_CRN_MASK   0x0000000000000780
+#define KVM_REG_ARM_VGIC_SYSREG_CRN_SHIFT  7
+#define KVM_REG_ARM_VGIC_SYSREG_CRM_MASK   0x0000000000000078
+#define KVM_REG_ARM_VGIC_SYSREG_CRM_SHIFT  3
+#define KVM_REG_ARM_VGIC_SYSREG_OP2_MASK   0x0000000000000007
+#define KVM_REG_ARM_VGIC_SYSREG_OP2_SHIFT  0
+
+#define KVM_DEV_ARM_VGIC_SYSREG_MASK (KVM_REG_ARM_VGIC_SYSREG_OP0_MASK | \
+				      KVM_REG_ARM_VGIC_SYSREG_OP1_MASK | \
+				      KVM_REG_ARM_VGIC_SYSREG_CRN_MASK | \
+				      KVM_REG_ARM_VGIC_SYSREG_CRM_MASK | \
+				      KVM_REG_ARM_VGIC_SYSREG_OP2_MASK)
+
 static inline bool irq_is_pending(struct vgic_irq *irq)
 {
 	if (irq->config == VGIC_CONFIG_EDGE)
@@ -139,6 +160,10 @@ int vgic_v3_dist_uaccess(struct kvm_vcpu *vcpu, bool is_write,
 			 int offset, u32 *val);
 int vgic_v3_redist_uaccess(struct kvm_vcpu *vcpu, bool is_write,
 			 int offset, u32 *val);
+int vgic_v3_cpu_sysregs_uaccess(struct kvm_vcpu *vcpu, bool is_write,
+			 u64 id, u64 *val);
+int vgic_v3_has_cpu_sysregs_attr(struct kvm_vcpu *vcpu, bool is_write, u64 id,
+				u64 *reg);
 int kvm_register_vgic_device(unsigned long type);
 void vgic_set_vmcr(struct kvm_vcpu *vcpu, struct vgic_vmcr *vmcr);
 void vgic_get_vmcr(struct kvm_vcpu *vcpu, struct vgic_vmcr *vmcr);