From mboxrd@z Thu Jan  1 00:00:00 1970
From: Marcelo Tosatti <mtosatti@redhat.com>
Subject: Re: [PATCH 3/3] KVM: Add KVM_VCPU_GET_REG_LIST/KVM_CAP_REG_LIST.
Date: Wed, 10 Oct 2012 15:12:39 -0300
Message-ID: <20121010181239.GA10649@amt.cnet>
References: <1346831926-31820-1-git-send-email-rusty.russell@linaro.org>
 <1346831926-31820-4-git-send-email-rusty.russell@linaro.org>
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Cc: kvm@vger.kernel.org, Avi Kivity <avi@redhat.com>,
	Christoffer Dall <c.dall@virtualopensystems.com>,
	Alexander Graf <agraf@suse.de>,
	Peter Maydell <peter.maydell@linaro.org>
To: Rusty Russell <rusty.russell@linaro.org>
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On Wed, Sep 05, 2012 at 05:28:46PM +0930, Rusty Russell wrote:
> This is a generic interface to find out what you can use
> KVM_GET_ONE_REG/KVM_SET_ONE_REG on.  Archs need to define
> KVM_HAVE_REG_LIST and then kvm_arch_num_regs() and
> kvm_arch_copy_reg_indices() functions.
>=20
> It's inspired by KVM_GET_MSR_INDEX_LIST, except it's a per-vcpu ioctl=
,
> and uses 64-bit indices.
>=20
> Signed-off-by: Rusty Russell <rusty.russell@linaro.org>
> ---
>  Documentation/virtual/kvm/api.txt |   20 ++++++++++++++++++++
>  include/linux/kvm.h               |   12 ++++++++++++
>  include/linux/kvm_host.h          |    5 ++++-
>  virt/kvm/kvm_main.c               |   20 ++++++++++++++++++++
>  4 files changed, 56 insertions(+), 1 deletion(-)
>=20
> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtua=
l/kvm/api.txt
> index b91bfd4..f30c3d0 100644
> --- a/Documentation/virtual/kvm/api.txt
> +++ b/Documentation/virtual/kvm/api.txt
> @@ -1985,6 +1985,26 @@ the virtualized real-mode area (VRMA) facility=
, the kernel will
>  re-create the VMRA HPTEs on the next KVM_RUN of any vcpu.)
> =20
> =20
> +4.76 KVM_VCPU_GET_REG_LIST
> +
> +Capability: KVM_CAP_REG_LIST
> +Architectures: all
> +Type: vcpu ioctl
> +Parameters: struct kvm_reg_list (in/out)
> +Returns: 0 on success; -1 on error
> +Errors:
> + =A0E2BIG: =A0=A0=A0=A0the reg index list is too big to fit in the a=
rray specified by
> + =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0the user (the number required w=
ill be written into n).
> +
> +struct kvm_reg_list {
> +	__u64 n; /* number of registers in reg[] */
> +	__u64 reg[0];
> +};
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 169a001..453fe93 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -2082,6 +2082,23 @@ out_free2:
>  		break;
>  	}
>  #endif
> +#ifdef KVM_HAVE_REG_LIST
> +	case KVM_VCPU_GET_REG_LIST: {
> +		struct kvm_reg_list __user *user_list =3D argp;
> +		struct kvm_reg_list reg_list;
> +		unsigned n;
> +
> +		if (copy_from_user(&reg_list, user_list, sizeof reg_list))
> +			return -EFAULT;
> +		n =3D reg_list.n;
> +		reg_list.n =3D kvm_arch_num_regs(vcpu);

The code does not actually support more than 2^32 registers, does it?
Why "__u64 n" ?