2022-11-28 16:20:29

by Anup Patel

Subject: [PATCH 8/9] RISC-V: KVM: Add ONE_REG interface for mvendorid, marchid, and mimpid

We add ONE_REG interface for VCPU mvendorid, marchid, and mimpid
so that KVM user-space can change this details to support migration
across heterogeneous hosts.

Signed-off-by: Anup Patel <[email protected]>
---
arch/riscv/include/uapi/asm/kvm.h | 3 +++
arch/riscv/kvm/vcpu.c | 27 +++++++++++++++++++++++++++
2 files changed, 30 insertions(+)

diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h
index 8985ff234c01..92af6f3f057c 100644
--- a/arch/riscv/include/uapi/asm/kvm.h
+++ b/arch/riscv/include/uapi/asm/kvm.h
@@ -49,6 +49,9 @@ struct kvm_sregs {
struct kvm_riscv_config {
unsigned long isa;
unsigned long zicbom_block_size;
+ unsigned long mvendorid;
+ unsigned long marchid;
+ unsigned long mimpid;
};

/* CORE registers for KVM_GET_ONE_REG and KVM_SET_ONE_REG */
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index 312a8a926867..7c08567097f0 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -276,6 +276,15 @@ static int kvm_riscv_vcpu_get_reg_config(struct kvm_vcpu *vcpu,
return -EINVAL;
reg_val = riscv_cbom_block_size;
break;
+ case KVM_REG_RISCV_CONFIG_REG(mvendorid):
+ reg_val = vcpu->arch.mvendorid;
+ break;
+ case KVM_REG_RISCV_CONFIG_REG(marchid):
+ reg_val = vcpu->arch.marchid;
+ break;
+ case KVM_REG_RISCV_CONFIG_REG(mimpid):
+ reg_val = vcpu->arch.mimpid;
+ break;
default:
return -EINVAL;
}
@@ -338,6 +347,24 @@ static int kvm_riscv_vcpu_set_reg_config(struct kvm_vcpu *vcpu,
break;
case KVM_REG_RISCV_CONFIG_REG(zicbom_block_size):
return -EOPNOTSUPP;
+ case KVM_REG_RISCV_CONFIG_REG(mvendorid):
+ if (!vcpu->arch.ran_atleast_once)
+ vcpu->arch.mvendorid = reg_val;
+ else
+ return -EBUSY;
+ break;
+ case KVM_REG_RISCV_CONFIG_REG(marchid):
+ if (!vcpu->arch.ran_atleast_once)
+ vcpu->arch.marchid = reg_val;
+ else
+ return -EBUSY;
+ break;
+ case KVM_REG_RISCV_CONFIG_REG(mimpid):
+ if (!vcpu->arch.ran_atleast_once)
+ vcpu->arch.mimpid = reg_val;
+ else
+ return -EBUSY;
+ break;
default:
return -EINVAL;
}
--
2.34.1

2022-11-28 21:29:25

by Atish Patra

Subject: Re: [PATCH 8/9] RISC-V: KVM: Add ONE_REG interface for mvendorid, marchid, and mimpid

On Mon, Nov 28, 2022 at 8:15 AM Anup Patel <[email protected]> wrote:
>
> We add ONE_REG interface for VCPU mvendorid, marchid, and mimpid
> so that KVM user-space can change this details to support migration
> across heterogeneous hosts.
>
> Signed-off-by: Anup Patel <[email protected]>
> ---
> arch/riscv/include/uapi/asm/kvm.h | 3 +++
> arch/riscv/kvm/vcpu.c | 27 +++++++++++++++++++++++++++
> 2 files changed, 30 insertions(+)
>
> diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h
> index 8985ff234c01..92af6f3f057c 100644
> --- a/arch/riscv/include/uapi/asm/kvm.h
> +++ b/arch/riscv/include/uapi/asm/kvm.h
> @@ -49,6 +49,9 @@ struct kvm_sregs {
> struct kvm_riscv_config {
> unsigned long isa;
> unsigned long zicbom_block_size;
> + unsigned long mvendorid;
> + unsigned long marchid;
> + unsigned long mimpid;
> };
>
> /* CORE registers for KVM_GET_ONE_REG and KVM_SET_ONE_REG */
> diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> index 312a8a926867..7c08567097f0 100644
> --- a/arch/riscv/kvm/vcpu.c
> +++ b/arch/riscv/kvm/vcpu.c
> @@ -276,6 +276,15 @@ static int kvm_riscv_vcpu_get_reg_config(struct kvm_vcpu *vcpu,
> return -EINVAL;
> reg_val = riscv_cbom_block_size;
> break;
> + case KVM_REG_RISCV_CONFIG_REG(mvendorid):
> + reg_val = vcpu->arch.mvendorid;
> + break;
> + case KVM_REG_RISCV_CONFIG_REG(marchid):
> + reg_val = vcpu->arch.marchid;
> + break;
> + case KVM_REG_RISCV_CONFIG_REG(mimpid):
> + reg_val = vcpu->arch.mimpid;
> + break;
> default:
> return -EINVAL;
> }
> @@ -338,6 +347,24 @@ static int kvm_riscv_vcpu_set_reg_config(struct kvm_vcpu *vcpu,
> break;
> case KVM_REG_RISCV_CONFIG_REG(zicbom_block_size):
> return -EOPNOTSUPP;
> + case KVM_REG_RISCV_CONFIG_REG(mvendorid):
> + if (!vcpu->arch.ran_atleast_once)
> + vcpu->arch.mvendorid = reg_val;
> + else
> + return -EBUSY;
> + break;
> + case KVM_REG_RISCV_CONFIG_REG(marchid):
> + if (!vcpu->arch.ran_atleast_once)
> + vcpu->arch.marchid = reg_val;
> + else
> + return -EBUSY;
> + break;
> + case KVM_REG_RISCV_CONFIG_REG(mimpid):
> + if (!vcpu->arch.ran_atleast_once)
> + vcpu->arch.mimpid = reg_val;
> + else
> + return -EBUSY;
> + break;
> default:
> return -EINVAL;
> }
> --
> 2.34.1
>

Reviewed-by: Atish Patra <[email protected]>

--
Regards,
Atish

2022-11-29 06:27:12

by Andrew Jones

Subject: Re: [PATCH 8/9] RISC-V: KVM: Add ONE_REG interface for mvendorid, marchid, and mimpid

On Mon, Nov 28, 2022 at 09:44:23PM +0530, Anup Patel wrote:
> We add ONE_REG interface for VCPU mvendorid, marchid, and mimpid
> so that KVM user-space can change this details to support migration
> across heterogeneous hosts.
>
> Signed-off-by: Anup Patel <[email protected]>
> ---
> arch/riscv/include/uapi/asm/kvm.h | 3 +++
> arch/riscv/kvm/vcpu.c | 27 +++++++++++++++++++++++++++
> 2 files changed, 30 insertions(+)
>
> diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h
> index 8985ff234c01..92af6f3f057c 100644
> --- a/arch/riscv/include/uapi/asm/kvm.h
> +++ b/arch/riscv/include/uapi/asm/kvm.h
> @@ -49,6 +49,9 @@ struct kvm_sregs {
> struct kvm_riscv_config {
> unsigned long isa;
> unsigned long zicbom_block_size;
> + unsigned long mvendorid;
> + unsigned long marchid;
> + unsigned long mimpid;
> };
>
> /* CORE registers for KVM_GET_ONE_REG and KVM_SET_ONE_REG */
> diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> index 312a8a926867..7c08567097f0 100644
> --- a/arch/riscv/kvm/vcpu.c
> +++ b/arch/riscv/kvm/vcpu.c
> @@ -276,6 +276,15 @@ static int kvm_riscv_vcpu_get_reg_config(struct kvm_vcpu *vcpu,
> return -EINVAL;
> reg_val = riscv_cbom_block_size;
> break;
> + case KVM_REG_RISCV_CONFIG_REG(mvendorid):
> + reg_val = vcpu->arch.mvendorid;
> + break;
> + case KVM_REG_RISCV_CONFIG_REG(marchid):
> + reg_val = vcpu->arch.marchid;
> + break;
> + case KVM_REG_RISCV_CONFIG_REG(mimpid):
> + reg_val = vcpu->arch.mimpid;
> + break;
> default:
> return -EINVAL;
> }
> @@ -338,6 +347,24 @@ static int kvm_riscv_vcpu_set_reg_config(struct kvm_vcpu *vcpu,
> break;
> case KVM_REG_RISCV_CONFIG_REG(zicbom_block_size):
> return -EOPNOTSUPP;
> + case KVM_REG_RISCV_CONFIG_REG(mvendorid):
> + if (!vcpu->arch.ran_atleast_once)
> + vcpu->arch.mvendorid = reg_val;
> + else
> + return -EBUSY;
> + break;
> + case KVM_REG_RISCV_CONFIG_REG(marchid):
> + if (!vcpu->arch.ran_atleast_once)
> + vcpu->arch.marchid = reg_val;
> + else
> + return -EBUSY;
> + break;
> + case KVM_REG_RISCV_CONFIG_REG(mimpid):
> + if (!vcpu->arch.ran_atleast_once)
> + vcpu->arch.mimpid = reg_val;
> + else
> + return -EBUSY;
> + break;
> default:
> return -EINVAL;
> }
> --
> 2.34.1
>

At some point we should patch Documentation/virt/kvm/api.rst to describe
the possible errors we have. It's missing EOPNOTSUPP and EBUSY.

Also, I see a couple places were we use EOPNOTSUPP that would be better
as EBUSY. And finally I wonder if we shouldn't use ENOENT when the reg_num
is wrong/unknown, which would allow us to differentiate between bad
reg_num and bad reg_val in set-one ioctls.

I can send an RFC series to better describe these thoughts.

And for this patch,

Reviewed-by: Andrew Jones <[email protected]>

Thanks,
drew

2022-12-03 12:44:06

by Anup Patel

Subject: Re: [PATCH 8/9] RISC-V: KVM: Add ONE_REG interface for mvendorid, marchid, and mimpid

On Tue, Nov 29, 2022 at 11:16 AM Andrew Jones <[email protected]> wrote:
>
> On Mon, Nov 28, 2022 at 09:44:23PM +0530, Anup Patel wrote:
> > We add ONE_REG interface for VCPU mvendorid, marchid, and mimpid
> > so that KVM user-space can change this details to support migration
> > across heterogeneous hosts.
> >
> > Signed-off-by: Anup Patel <[email protected]>
> > ---
> > arch/riscv/include/uapi/asm/kvm.h | 3 +++
> > arch/riscv/kvm/vcpu.c | 27 +++++++++++++++++++++++++++
> > 2 files changed, 30 insertions(+)
> >
> > diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h
> > index 8985ff234c01..92af6f3f057c 100644
> > --- a/arch/riscv/include/uapi/asm/kvm.h
> > +++ b/arch/riscv/include/uapi/asm/kvm.h
> > @@ -49,6 +49,9 @@ struct kvm_sregs {
> > struct kvm_riscv_config {
> > unsigned long isa;
> > unsigned long zicbom_block_size;
> > + unsigned long mvendorid;
> > + unsigned long marchid;
> > + unsigned long mimpid;
> > };
> >
> > /* CORE registers for KVM_GET_ONE_REG and KVM_SET_ONE_REG */
> > diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> > index 312a8a926867..7c08567097f0 100644
> > --- a/arch/riscv/kvm/vcpu.c
> > +++ b/arch/riscv/kvm/vcpu.c
> > @@ -276,6 +276,15 @@ static int kvm_riscv_vcpu_get_reg_config(struct kvm_vcpu *vcpu,
> > return -EINVAL;
> > reg_val = riscv_cbom_block_size;
> > break;
> > + case KVM_REG_RISCV_CONFIG_REG(mvendorid):
> > + reg_val = vcpu->arch.mvendorid;
> > + break;
> > + case KVM_REG_RISCV_CONFIG_REG(marchid):
> > + reg_val = vcpu->arch.marchid;
> > + break;
> > + case KVM_REG_RISCV_CONFIG_REG(mimpid):
> > + reg_val = vcpu->arch.mimpid;
> > + break;
> > default:
> > return -EINVAL;
> > }
> > @@ -338,6 +347,24 @@ static int kvm_riscv_vcpu_set_reg_config(struct kvm_vcpu *vcpu,
> > break;
> > case KVM_REG_RISCV_CONFIG_REG(zicbom_block_size):
> > return -EOPNOTSUPP;
> > + case KVM_REG_RISCV_CONFIG_REG(mvendorid):
> > + if (!vcpu->arch.ran_atleast_once)
> > + vcpu->arch.mvendorid = reg_val;
> > + else
> > + return -EBUSY;
> > + break;
> > + case KVM_REG_RISCV_CONFIG_REG(marchid):
> > + if (!vcpu->arch.ran_atleast_once)
> > + vcpu->arch.marchid = reg_val;
> > + else
> > + return -EBUSY;
> > + break;
> > + case KVM_REG_RISCV_CONFIG_REG(mimpid):
> > + if (!vcpu->arch.ran_atleast_once)
> > + vcpu->arch.mimpid = reg_val;
> > + else
> > + return -EBUSY;
> > + break;
> > default:
> > return -EINVAL;
> > }
> > --
> > 2.34.1
> >
>
> At some point we should patch Documentation/virt/kvm/api.rst to describe
> the possible errors we have. It's missing EOPNOTSUPP and EBUSY.
>
> Also, I see a couple places were we use EOPNOTSUPP that would be better
> as EBUSY. And finally I wonder if we shouldn't use ENOENT when the reg_num
> is wrong/unknown, which would allow us to differentiate between bad
> reg_num and bad reg_val in set-one ioctls.
>
> I can send an RFC series to better describe these thoughts.

Sure, go ahead.

>
> And for this patch,
>
> Reviewed-by: Andrew Jones <[email protected]>
>
> Thanks,
> drew

Regards,
Anup