Re: [PATCH 10/10] RISC-V: KVM: Expose IMSIC registers as attributes of AIA irqchip

From: Atish Patra
Date: Wed Jun 07 2023 - 19:17:35 EST

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On Wed, May 17, 2023 at 3:52 AM Anup Patel <apatel@xxxxxxxxxxxxxxxx> wrote:
>
> We expose IMSIC registers as KVM device attributes of the in-kernel
> AIA irqchip device. This will allow KVM user-space to save/restore
> IMISC state of each VCPU using KVM device ioctls().
>
> Signed-off-by: Anup Patel <apatel@xxxxxxxxxxxxxxxx>
> ---
> arch/riscv/include/asm/kvm_aia.h | 3 +
> arch/riscv/include/uapi/asm/kvm.h | 12 +++
> arch/riscv/kvm/aia_device.c | 29 ++++-
> arch/riscv/kvm/aia_imsic.c | 170 ++++++++++++++++++++++++++++++
> 4 files changed, 212 insertions(+), 2 deletions(-)
>
> diff --git a/arch/riscv/include/asm/kvm_aia.h b/arch/riscv/include/asm/kvm_aia.h
> index a4f6ebf90e31..1f37b600ca47 100644
> --- a/arch/riscv/include/asm/kvm_aia.h
> +++ b/arch/riscv/include/asm/kvm_aia.h
> @@ -97,6 +97,9 @@ int kvm_riscv_vcpu_aia_imsic_update(struct kvm_vcpu *vcpu);
> int kvm_riscv_vcpu_aia_imsic_rmw(struct kvm_vcpu *vcpu, unsigned long isel,
> unsigned long *val, unsigned long new_val,
> unsigned long wr_mask);
> +int kvm_riscv_aia_imsic_rw_attr(struct kvm *kvm, unsigned long type,
> + bool write, unsigned long *val);
> +int kvm_riscv_aia_imsic_has_attr(struct kvm *kvm, unsigned long type);
> void kvm_riscv_vcpu_aia_imsic_reset(struct kvm_vcpu *vcpu);
> int kvm_riscv_vcpu_aia_imsic_inject(struct kvm_vcpu *vcpu,
> u32 guest_index, u32 offset, u32 iid);
> diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h
> index e80210c2220b..624784bb21dd 100644
> --- a/arch/riscv/include/uapi/asm/kvm.h
> +++ b/arch/riscv/include/uapi/asm/kvm.h
> @@ -242,6 +242,18 @@ enum KVM_RISCV_SBI_EXT_ID {
>
> #define KVM_DEV_RISCV_AIA_GRP_APLIC 3
>
> +#define KVM_DEV_RISCV_AIA_GRP_IMSIC 4
> +#define KVM_DEV_RISCV_AIA_IMSIC_ISEL_BITS 12
> +#define KVM_DEV_RISCV_AIA_IMSIC_ISEL_MASK \
> + ((1U << KVM_DEV_RISCV_AIA_IMSIC_ISEL_BITS) - 1)
> +#define KVM_DEV_RISCV_AIA_IMSIC_MKATTR(__vcpu, __isel) \
> + (((__vcpu) << KVM_DEV_RISCV_AIA_IMSIC_ISEL_BITS) | \
> + ((__isel) & KVM_DEV_RISCV_AIA_IMSIC_ISEL_MASK))
> +#define KVM_DEV_RISCV_AIA_IMSIC_GET_ISEL(__attr) \
> + ((__attr) & KVM_DEV_RISCV_AIA_IMSIC_ISEL_MASK)
> +#define KVM_DEV_RISCV_AIA_IMSIC_GET_VCPU(__attr) \
> + ((__attr) >> KVM_DEV_RISCV_AIA_IMSIC_ISEL_BITS)
> +
> /* One single KVM irqchip, ie. the AIA */
> #define KVM_NR_IRQCHIPS 1
>
> diff --git a/arch/riscv/kvm/aia_device.c b/arch/riscv/kvm/aia_device.c
> index 17dba92a90e1..ac7bd98301a3 100644
> --- a/arch/riscv/kvm/aia_device.c
> +++ b/arch/riscv/kvm/aia_device.c
> @@ -326,7 +326,7 @@ static int aia_set_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
> u32 nr;
> u64 addr;
> int nr_vcpus, r = -ENXIO;
> - unsigned long type = (unsigned long)attr->attr;
> + unsigned long v, type = (unsigned long)attr->attr;
> void __user *uaddr = (void __user *)(long)attr->addr;
>
> switch (attr->group) {
> @@ -373,6 +373,15 @@ static int aia_set_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
> r = kvm_riscv_aia_aplic_set_attr(dev->kvm, type, nr);
> mutex_unlock(&dev->kvm->lock);
>
> + break;
> + case KVM_DEV_RISCV_AIA_GRP_IMSIC:
> + if (copy_from_user(&v, uaddr, sizeof(v)))
> + return -EFAULT;
> +
> + mutex_lock(&dev->kvm->lock);
> + r = kvm_riscv_aia_imsic_rw_attr(dev->kvm, type, true, &v);
> + mutex_unlock(&dev->kvm->lock);
> +
> break;
> }
>
> @@ -385,7 +394,7 @@ static int aia_get_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
> u64 addr;
> int nr_vcpus, r = -ENXIO;
> void __user *uaddr = (void __user *)(long)attr->addr;
> - unsigned long type = (unsigned long)attr->attr;
> + unsigned long v, type = (unsigned long)attr->attr;
>
> switch (attr->group) {
> case KVM_DEV_RISCV_AIA_GRP_CONFIG:
> @@ -434,6 +443,20 @@ static int aia_get_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
> if (copy_to_user(uaddr, &nr, sizeof(nr)))
> return -EFAULT;
>
> + break;
> + case KVM_DEV_RISCV_AIA_GRP_IMSIC:
> + if (copy_from_user(&v, uaddr, sizeof(v)))
> + return -EFAULT;
> +
> + mutex_lock(&dev->kvm->lock);
> + r = kvm_riscv_aia_imsic_rw_attr(dev->kvm, type, false, &v);
> + mutex_unlock(&dev->kvm->lock);
> + if (r)
> + return r;
> +
> + if (copy_to_user(uaddr, &v, sizeof(v)))
> + return -EFAULT;
> +
> break;
> }
>
> @@ -472,6 +495,8 @@ static int aia_has_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
> break;
> case KVM_DEV_RISCV_AIA_GRP_APLIC:
> return kvm_riscv_aia_aplic_has_attr(dev->kvm, attr->attr);
> + case KVM_DEV_RISCV_AIA_GRP_IMSIC:
> + return kvm_riscv_aia_imsic_has_attr(dev->kvm, attr->attr);
> }
>
> return -ENXIO;
> diff --git a/arch/riscv/kvm/aia_imsic.c b/arch/riscv/kvm/aia_imsic.c
> index 2dc09dcb8ab5..8f108cfa80e5 100644
> --- a/arch/riscv/kvm/aia_imsic.c
> +++ b/arch/riscv/kvm/aia_imsic.c
> @@ -277,6 +277,33 @@ static u32 imsic_mrif_topei(struct imsic_mrif *mrif, u32 nr_eix, u32 nr_msis)
> return 0;
> }
>
> +static int imsic_mrif_isel_check(u32 nr_eix, unsigned long isel)
> +{
> + u32 num = 0;
> +
> + switch (isel) {
> + case IMSIC_EIDELIVERY:
> + case IMSIC_EITHRESHOLD:
> + break;
> + case IMSIC_EIP0 ... IMSIC_EIP63:
> + num = isel - IMSIC_EIP0;
> + break;
> + case IMSIC_EIE0 ... IMSIC_EIE63:
> + num = isel - IMSIC_EIE0;
> + break;
> + default:
> + return -ENOENT;
> + };
> +#ifndef CONFIG_32BIT
> + if (num & 0x1)
> + return -EINVAL;
> +#endif
> + if ((num / 2) >= nr_eix)
> + return -EINVAL;
> +
> + return 0;
> +}
> +
> static int imsic_mrif_rmw(struct imsic_mrif *mrif, u32 nr_eix,
> unsigned long isel, unsigned long *val,
> unsigned long new_val, unsigned long wr_mask)
> @@ -407,6 +434,86 @@ static void imsic_vsfile_read(int vsfile_hgei, int vsfile_cpu, u32 nr_eix,
> imsic_vsfile_local_read, &idata, 1);
> }
>
> +struct imsic_vsfile_rw_data {
> + int hgei;
> + int isel;
> + bool write;
> + unsigned long val;
> +};
> +
> +static void imsic_vsfile_local_rw(void *data)
> +{
> + struct imsic_vsfile_rw_data *idata = data;
> + unsigned long new_hstatus, old_hstatus, old_vsiselect;
> +
> + old_vsiselect = csr_read(CSR_VSISELECT);
> + old_hstatus = csr_read(CSR_HSTATUS);
> + new_hstatus = old_hstatus & ~HSTATUS_VGEIN;
> + new_hstatus |= ((unsigned long)idata->hgei) << HSTATUS_VGEIN_SHIFT;
> + csr_write(CSR_HSTATUS, new_hstatus);
> +
> + switch (idata->isel) {
> + case IMSIC_EIDELIVERY:
> + if (idata->write)
> + imsic_vs_csr_write(IMSIC_EIDELIVERY, idata->val);
> + else
> + idata->val = imsic_vs_csr_read(IMSIC_EIDELIVERY);
> + break;
> + case IMSIC_EITHRESHOLD:
> + if (idata->write)
> + imsic_vs_csr_write(IMSIC_EITHRESHOLD, idata->val);
> + else
> + idata->val = imsic_vs_csr_read(IMSIC_EITHRESHOLD);
> + break;
> + case IMSIC_EIP0 ... IMSIC_EIP63:
> + case IMSIC_EIE0 ... IMSIC_EIE63:
> +#ifndef CONFIG_32BIT
> + if (idata->isel & 0x1)
> + break;
> +#endif
> + if (idata->write)
> + imsic_eix_write(idata->isel, idata->val);
> + else
> + idata->val = imsic_eix_read(idata->isel);
> + break;
> + default:
> + break;
> + }
> +
> + csr_write(CSR_HSTATUS, old_hstatus);
> + csr_write(CSR_VSISELECT, old_vsiselect);
> +}
> +
> +static int imsic_vsfile_rw(int vsfile_hgei, int vsfile_cpu, u32 nr_eix,
> + unsigned long isel, bool write,
> + unsigned long *val)
> +{
> + int rc;
> + struct imsic_vsfile_rw_data rdata;
> +
> + /* We can only access register if we have a IMSIC VS-file */
> + if (vsfile_cpu < 0 || vsfile_hgei <= 0)
> + return -EINVAL;
> +
> + /* Check IMSIC register iselect */
> + rc = imsic_mrif_isel_check(nr_eix, isel);
> + if (rc)
> + return rc;
> +
> + /* We can only access register on local CPU */
> + rdata.hgei = vsfile_hgei;
> + rdata.isel = isel;
> + rdata.write = write;
> + rdata.val = (write) ? *val : 0;
> + on_each_cpu_mask(cpumask_of(vsfile_cpu),
> + imsic_vsfile_local_rw, &rdata, 1);
> +
> + if (!write)
> + *val = rdata.val;
> +
> + return 0;
> +}
> +
> static void imsic_vsfile_local_clear(int vsfile_hgei, u32 nr_eix)
> {
> u32 i;
> @@ -758,6 +865,69 @@ int kvm_riscv_vcpu_aia_imsic_rmw(struct kvm_vcpu *vcpu, unsigned long isel,
> return rc;
> }
>
> +int kvm_riscv_aia_imsic_rw_attr(struct kvm *kvm, unsigned long type,
> + bool write, unsigned long *val)
> +{
> + u32 isel, vcpu_id;
> + unsigned long flags;
> + struct imsic *imsic;
> + struct kvm_vcpu *vcpu;
> + int rc, vsfile_hgei, vsfile_cpu;
> +
> + if (!kvm_riscv_aia_initialized(kvm))
> + return -ENODEV;
> +
> + vcpu_id = KVM_DEV_RISCV_AIA_IMSIC_GET_VCPU(type);
> + vcpu = kvm_get_vcpu_by_id(kvm, vcpu_id);
> + if (!vcpu)
> + return -ENODEV;
> +
> + isel = KVM_DEV_RISCV_AIA_IMSIC_GET_ISEL(type);
> + imsic = vcpu->arch.aia_context.imsic_state;
> +
> + read_lock_irqsave(&imsic->vsfile_lock, flags);
> +
> + rc = 0;
> + vsfile_hgei = imsic->vsfile_hgei;
> + vsfile_cpu = imsic->vsfile_cpu;
> + if (vsfile_cpu < 0) {
> + if (write) {
> + rc = imsic_mrif_rmw(imsic->swfile, imsic->nr_eix,
> + isel, NULL, *val, -1UL);
> + imsic_swfile_extirq_update(vcpu);
> + } else
> + rc = imsic_mrif_rmw(imsic->swfile, imsic->nr_eix,
> + isel, val, 0, 0);
> + }
> +
> + read_unlock_irqrestore(&imsic->vsfile_lock, flags);
> +
> + if (!rc && vsfile_cpu >= 0)
> + rc = imsic_vsfile_rw(vsfile_hgei, vsfile_cpu, imsic->nr_eix,
> + isel, write, val);
> +
> + return rc;
> +}
> +
> +int kvm_riscv_aia_imsic_has_attr(struct kvm *kvm, unsigned long type)
> +{
> + u32 isel, vcpu_id;
> + struct imsic *imsic;
> + struct kvm_vcpu *vcpu;
> +
> + if (!kvm_riscv_aia_initialized(kvm))
> + return -ENODEV;
> +
> + vcpu_id = KVM_DEV_RISCV_AIA_IMSIC_GET_VCPU(type);
> + vcpu = kvm_get_vcpu_by_id(kvm, vcpu_id);
> + if (!vcpu)
> + return -ENODEV;
> +
> + isel = KVM_DEV_RISCV_AIA_IMSIC_GET_ISEL(type);
> + imsic = vcpu->arch.aia_context.imsic_state;
> + return imsic_mrif_isel_check(imsic->nr_eix, isel);
> +}
> +
> void kvm_riscv_vcpu_aia_imsic_reset(struct kvm_vcpu *vcpu)
> {
> struct imsic *imsic = vcpu->arch.aia_context.imsic_state;
> --
> 2.34.1
>

Reviewed-by: Atish Patra <atishp@xxxxxxxxxxxx>
--
Regards,
Atish

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