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From:   Anup Patel <Anup.Patel@wdc.com>
To:     Palmer Dabbelt <palmer@sifive.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Radim K <rkrcmar@redhat.com>
CC:     Daniel Lezcano <daniel.lezcano@linaro.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Atish Patra <Atish.Patra@wdc.com>,
        Alistair Francis <Alistair.Francis@wdc.com>,
        Damien Le Moal <Damien.LeMoal@wdc.com>,
        Christoph Hellwig <hch@infradead.org>,
        Anup Patel <anup@brainfault.org>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        "linux-riscv@lists.infradead.org" <linux-riscv@lists.infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Anup Patel <Anup.Patel@wdc.com>
Subject: [PATCH v4 08/20] RISC-V: KVM: Implement
 KVM_GET_ONE_REG/KVM_SET_ONE_REG ioctls
Thread-Topic: [PATCH v4 08/20] RISC-V: KVM: Implement
 KVM_GET_ONE_REG/KVM_SET_ONE_REG ioctls
Thread-Index: AQHVTRumjB3cjubtMkyNVKgO99In9A==
Date:   Wed, 7 Aug 2019 12:28:43 +0000
Message-ID: <20190807122726.81544-9-anup.patel@wdc.com>
References: <20190807122726.81544-1-anup.patel@wdc.com>
In-Reply-To: <20190807122726.81544-1-anup.patel@wdc.com>
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For KVM RISC-V, we use KVM_GET_ONE_REG/KVM_SET_ONE_REG ioctls to access
VCPU config and registers from user-space.

We have three types of VCPU registers:
1. CONFIG - these are VCPU config and capabilities
2. CORE   - these are VCPU general purpose registers
3. CSR    - these are VCPU control and status registers

The CONFIG registers available to user-space are ISA and TIMEBASE. Out
of these, TIMEBASE is a read-only register which inform user-space about
VCPU timer base frequency. The ISA register is a read and write register
where user-space can only write the desired VCPU ISA capabilities before
running the VCPU.

The CORE registers available to user-space are PC, RA, SP, GP, TP, A0-A7,
T0-T6, S0-S11 and MODE. Most of these are RISC-V general registers except
PC and MODE. The PC register represents program counter whereas the MODE
register represent VCPU privilege mode (i.e. S/U-mode).

The CSRs available to user-space are SSTATUS, SIE, STVEC, SSCRATCH, SEPC,
SCAUSE, STVAL, SIP, and SATP. All of these are read/write registers.

In future, more VCPU register types will be added (such as FP) for the
KVM_GET_ONE_REG/KVM_SET_ONE_REG ioctls.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
---
 arch/riscv/include/uapi/asm/kvm.h |  40 ++++-
 arch/riscv/kvm/vcpu.c             | 235 +++++++++++++++++++++++++++++-
 2 files changed, 272 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/as=
m/kvm.h
index 6dbc056d58ba..024f220eb17e 100644
--- a/arch/riscv/include/uapi/asm/kvm.h
+++ b/arch/riscv/include/uapi/asm/kvm.h
@@ -23,8 +23,15 @@
=20
 /* for KVM_GET_REGS and KVM_SET_REGS */
 struct kvm_regs {
+	/* out (KVM_GET_REGS) / in (KVM_SET_REGS) */
+	struct user_regs_struct regs;
+	unsigned long mode;
 };
=20
+/* Possible privilege modes for kvm_regs */
+#define KVM_RISCV_MODE_S	1
+#define KVM_RISCV_MODE_U	0
+
 /* for KVM_GET_FPU and KVM_SET_FPU */
 struct kvm_fpu {
 };
@@ -41,10 +48,41 @@ struct kvm_guest_debug_arch {
 struct kvm_sync_regs {
 };
=20
-/* dummy definition */
+/* for KVM_GET_SREGS and KVM_SET_SREGS */
 struct kvm_sregs {
+	unsigned long sstatus;
+	unsigned long sie;
+	unsigned long stvec;
+	unsigned long sscratch;
+	unsigned long sepc;
+	unsigned long scause;
+	unsigned long stval;
+	unsigned long sip;
+	unsigned long satp;
 };
=20
+#define KVM_REG_SIZE(id)		\
+	(1U << (((id) & KVM_REG_SIZE_MASK) >> KVM_REG_SIZE_SHIFT))
+
+/* If you need to interpret the index values, here is the key: */
+#define KVM_REG_RISCV_TYPE_MASK		0x00000000FF000000
+#define KVM_REG_RISCV_TYPE_SHIFT	24
+
+/* Config registers are mapped as type 1 */
+#define KVM_REG_RISCV_CONFIG		(0x01 << KVM_REG_RISCV_TYPE_SHIFT)
+#define KVM_REG_RISCV_CONFIG_ISA	0x0
+#define KVM_REG_RISCV_CONFIG_TIMEBASE	0x1
+
+/* Core registers are mapped as type 2 */
+#define KVM_REG_RISCV_CORE		(0x02 << KVM_REG_RISCV_TYPE_SHIFT)
+#define KVM_REG_RISCV_CORE_REG(name)	\
+		(offsetof(struct kvm_regs, name) / sizeof(unsigned long))
+
+/* Control and status registers are mapped as type 3 */
+#define KVM_REG_RISCV_CSR		(0x03 << KVM_REG_RISCV_TYPE_SHIFT)
+#define KVM_REG_RISCV_CSR_REG(name)	\
+		(offsetof(struct kvm_sregs, name) / sizeof(unsigned long))
+
 #endif
=20
 #endif /* __LINUX_KVM_RISCV_H */
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index 7f59e85c6af8..9396a83c0611 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -164,6 +164,215 @@ vm_fault_t kvm_arch_vcpu_fault(struct kvm_vcpu *vcpu,=
 struct vm_fault *vmf)
 	return VM_FAULT_SIGBUS;
 }
=20
+static int kvm_riscv_vcpu_get_reg_config(struct kvm_vcpu *vcpu,
+					 const struct kvm_one_reg *reg)
+{
+	unsigned long __user *uaddr =3D
+			(unsigned long __user *)(unsigned long)reg->addr;
+	unsigned long reg_num =3D reg->id & ~(KVM_REG_ARCH_MASK |
+					    KVM_REG_SIZE_MASK |
+					    KVM_REG_RISCV_CONFIG);
+	unsigned long reg_val;
+
+	if (KVM_REG_SIZE(reg->id) !=3D sizeof(unsigned long))
+		return -EINVAL;
+
+	switch (reg_num) {
+	case KVM_REG_RISCV_CONFIG_ISA:
+		reg_val =3D vcpu->arch.isa;
+		break;
+	case KVM_REG_RISCV_CONFIG_TIMEBASE:
+		reg_val =3D riscv_timebase;
+		break;
+	default:
+		return -EINVAL;
+	};
+
+	if (copy_to_user(uaddr, &reg_val, KVM_REG_SIZE(reg->id)))
+		return -EFAULT;
+
+	return 0;
+}
+
+static int kvm_riscv_vcpu_set_reg_config(struct kvm_vcpu *vcpu,
+					 const struct kvm_one_reg *reg)
+{
+	unsigned long __user *uaddr =3D
+			(unsigned long __user *)(unsigned long)reg->addr;
+	unsigned long reg_num =3D reg->id & ~(KVM_REG_ARCH_MASK |
+					    KVM_REG_SIZE_MASK |
+					    KVM_REG_RISCV_CONFIG);
+	unsigned long reg_val;
+
+	if (KVM_REG_SIZE(reg->id) !=3D sizeof(unsigned long))
+		return -EINVAL;
+
+	if (copy_from_user(&reg_val, uaddr, KVM_REG_SIZE(reg->id)))
+		return -EFAULT;
+
+	switch (reg_num) {
+	case KVM_REG_RISCV_CONFIG_ISA:
+		if (!vcpu->arch.ran_atleast_once) {
+			vcpu->arch.isa =3D reg_val;
+			vcpu->arch.isa &=3D riscv_isa_extension_base(NULL);
+			vcpu->arch.isa &=3D KVM_RISCV_ISA_ALLOWED;
+		} else {
+			return -ENOTSUPP;
+		}
+		break;
+	case KVM_REG_RISCV_CONFIG_TIMEBASE:
+		return -ENOTSUPP;
+	default:
+		return -EINVAL;
+	};
+
+	return 0;
+}
+
+static int kvm_riscv_vcpu_get_reg_core(struct kvm_vcpu *vcpu,
+				       const struct kvm_one_reg *reg)
+{
+	struct kvm_cpu_context *cntx =3D &vcpu->arch.guest_context;
+	unsigned long __user *uaddr =3D
+			(unsigned long __user *)(unsigned long)reg->addr;
+	unsigned long reg_num =3D reg->id & ~(KVM_REG_ARCH_MASK |
+					    KVM_REG_SIZE_MASK |
+					    KVM_REG_RISCV_CORE);
+	unsigned long reg_val;
+
+	if (KVM_REG_SIZE(reg->id) !=3D sizeof(unsigned long))
+		return -EINVAL;
+
+	if (reg_num =3D=3D KVM_REG_RISCV_CORE_REG(regs.pc))
+		reg_val =3D cntx->sepc;
+	else if (KVM_REG_RISCV_CORE_REG(regs.pc) < reg_num &&
+		 reg_num <=3D KVM_REG_RISCV_CORE_REG(regs.t6))
+		reg_val =3D ((unsigned long *)cntx)[reg_num];
+	else if (reg_num =3D=3D KVM_REG_RISCV_CORE_REG(mode))
+		reg_val =3D (cntx->sstatus & SR_SPP) ?
+				KVM_RISCV_MODE_S : KVM_RISCV_MODE_U;
+	else
+		return -EINVAL;
+
+	if (copy_to_user(uaddr, &reg_val, KVM_REG_SIZE(reg->id)))
+		return -EFAULT;
+
+	return 0;
+}
+
+static int kvm_riscv_vcpu_set_reg_core(struct kvm_vcpu *vcpu,
+				       const struct kvm_one_reg *reg)
+{
+	struct kvm_cpu_context *cntx =3D &vcpu->arch.guest_context;
+	unsigned long __user *uaddr =3D
+			(unsigned long __user *)(unsigned long)reg->addr;
+	unsigned long reg_num =3D reg->id & ~(KVM_REG_ARCH_MASK |
+					    KVM_REG_SIZE_MASK |
+					    KVM_REG_RISCV_CORE);
+	unsigned long reg_val;
+
+	if (KVM_REG_SIZE(reg->id) !=3D sizeof(unsigned long))
+		return -EINVAL;
+
+	if (copy_from_user(&reg_val, uaddr, KVM_REG_SIZE(reg->id)))
+		return -EFAULT;
+
+	if (reg_num =3D=3D KVM_REG_RISCV_CORE_REG(regs.pc))
+		cntx->sepc =3D reg_val;
+	else if (KVM_REG_RISCV_CORE_REG(regs.pc) < reg_num &&
+		 reg_num <=3D KVM_REG_RISCV_CORE_REG(regs.t6))
+		((unsigned long *)cntx)[reg_num] =3D reg_val;
+	else if (reg_num =3D=3D KVM_REG_RISCV_CORE_REG(mode)) {
+		if (reg_val =3D=3D KVM_RISCV_MODE_S)
+			cntx->sstatus |=3D SR_SPP;
+		else
+			cntx->sstatus &=3D ~SR_SPP;
+	} else
+		return -EINVAL;
+
+	return 0;
+}
+
+static int kvm_riscv_vcpu_get_reg_csr(struct kvm_vcpu *vcpu,
+				      const struct kvm_one_reg *reg)
+{
+	struct kvm_vcpu_csr *csr =3D &vcpu->arch.guest_csr;
+	unsigned long __user *uaddr =3D
+			(unsigned long __user *)(unsigned long)reg->addr;
+	unsigned long reg_num =3D reg->id & ~(KVM_REG_ARCH_MASK |
+					    KVM_REG_SIZE_MASK |
+					    KVM_REG_RISCV_CSR);
+	unsigned long reg_val;
+
+	if (KVM_REG_SIZE(reg->id) !=3D sizeof(unsigned long))
+		return -EINVAL;
+	if (reg_num >=3D sizeof(struct kvm_sregs) / sizeof(unsigned long))
+		return -EINVAL;
+
+	if (reg_num =3D=3D KVM_REG_RISCV_CSR_REG(sip))
+		kvm_riscv_vcpu_flush_interrupts(vcpu);
+
+	reg_val =3D ((unsigned long *)csr)[reg_num];
+
+	if (copy_to_user(uaddr, &reg_val, KVM_REG_SIZE(reg->id)))
+		return -EFAULT;
+
+	return 0;
+}
+
+static int kvm_riscv_vcpu_set_reg_csr(struct kvm_vcpu *vcpu,
+				      const struct kvm_one_reg *reg)
+{
+	struct kvm_vcpu_csr *csr =3D &vcpu->arch.guest_csr;
+	unsigned long __user *uaddr =3D
+			(unsigned long __user *)(unsigned long)reg->addr;
+	unsigned long reg_num =3D reg->id & ~(KVM_REG_ARCH_MASK |
+					    KVM_REG_SIZE_MASK |
+					    KVM_REG_RISCV_CSR);
+	unsigned long reg_val;
+
+	if (KVM_REG_SIZE(reg->id) !=3D sizeof(unsigned long))
+		return -EINVAL;
+	if (reg_num >=3D sizeof(struct kvm_sregs) / sizeof(unsigned long))
+		return -EINVAL;
+
+	if (copy_from_user(&reg_val, uaddr, KVM_REG_SIZE(reg->id)))
+		return -EFAULT;
+
+	((unsigned long *)csr)[reg_num] =3D reg_val;
+
+	if (reg_num =3D=3D KVM_REG_RISCV_CSR_REG(sip))
+		WRITE_ONCE(vcpu->arch.irqs_pending_mask, 0);
+
+	return 0;
+}
+
+static int kvm_riscv_vcpu_set_reg(struct kvm_vcpu *vcpu,
+				  const struct kvm_one_reg *reg)
+{
+	if ((reg->id & KVM_REG_RISCV_TYPE_MASK) =3D=3D KVM_REG_RISCV_CONFIG)
+		return kvm_riscv_vcpu_set_reg_config(vcpu, reg);
+	else if ((reg->id & KVM_REG_RISCV_TYPE_MASK) =3D=3D KVM_REG_RISCV_CORE)
+		return kvm_riscv_vcpu_set_reg_core(vcpu, reg);
+	else if ((reg->id & KVM_REG_RISCV_TYPE_MASK) =3D=3D KVM_REG_RISCV_CSR)
+		return kvm_riscv_vcpu_set_reg_csr(vcpu, reg);
+
+	return -EINVAL;
+}
+
+static int kvm_riscv_vcpu_get_reg(struct kvm_vcpu *vcpu,
+				  const struct kvm_one_reg *reg)
+{
+	if ((reg->id & KVM_REG_RISCV_TYPE_MASK) =3D=3D KVM_REG_RISCV_CONFIG)
+		return kvm_riscv_vcpu_get_reg_config(vcpu, reg);
+	else if ((reg->id & KVM_REG_RISCV_TYPE_MASK) =3D=3D KVM_REG_RISCV_CORE)
+		return kvm_riscv_vcpu_get_reg_core(vcpu, reg);
+	else if ((reg->id & KVM_REG_RISCV_TYPE_MASK) =3D=3D KVM_REG_RISCV_CSR)
+		return kvm_riscv_vcpu_get_reg_csr(vcpu, reg);
+
+	return -EINVAL;
+}
+
 long kvm_arch_vcpu_async_ioctl(struct file *filp,
 			       unsigned int ioctl, unsigned long arg)
 {
@@ -188,8 +397,30 @@ long kvm_arch_vcpu_async_ioctl(struct file *filp,
 long kvm_arch_vcpu_ioctl(struct file *filp,
 			 unsigned int ioctl, unsigned long arg)
 {
-	/* TODO: */
-	return -EINVAL;
+	struct kvm_vcpu *vcpu =3D filp->private_data;
+	void __user *argp =3D (void __user *)arg;
+	long r =3D -EINVAL;
+
+	switch (ioctl) {
+	case KVM_SET_ONE_REG:
+	case KVM_GET_ONE_REG: {
+		struct kvm_one_reg reg;
+
+		r =3D -EFAULT;
+		if (copy_from_user(&reg, argp, sizeof(reg)))
+			break;
+
+		if (ioctl =3D=3D KVM_SET_ONE_REG)
+			r =3D kvm_riscv_vcpu_set_reg(vcpu, &reg);
+		else
+			r =3D kvm_riscv_vcpu_get_reg(vcpu, &reg);
+		break;
+	}
+	default:
+		break;
+	}
+
+	return r;
 }
=20
 int kvm_arch_vcpu_ioctl_get_sregs(struct kvm_vcpu *vcpu,
--=20
2.17.1