Re: [RFC PATCH v2 18/22] i386/xen: handle VCPUOP_register_runstate_memory_area

[Paul Durrant]

On 09/12/2022 09:56, David Woodhouse wrote:
> From: Joao Martins <joao.m.martins@oracle.com>
>
> Allow guest to setup the vcpu runstates which is used as
> steal clock.
>
> Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
> Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
> ---
>   target/i386/cpu.h     |  1 +
>   target/i386/kvm/kvm.c |  9 +++++++++
>   target/i386/machine.c |  4 +++-
>   target/i386/xen.c     | 35 +++++++++++++++++++++++++++++++++++
>   4 files changed, 48 insertions(+), 1 deletion(-)
[snip]
> +static int vcpuop_register_runstate_info(CPUState *cs, CPUState *target,
> +                                         uint64_t arg)
> +{
> +    struct vcpu_register_runstate_memory_area rma;
> +    uint64_t gpa;
> +    size_t len;
> +
> +    if (kvm_copy_from_gva(cs, arg, &rma, sizeof(*rma.addr.v))) {
> +        return -EFAULT;
> +    }
> +
> +    if (!kvm_gva_to_gpa(cs, rma.addr.p, &gpa, &len, false) ||
> +        len < sizeof(struct vcpu_time_info)) {
> +        return -EFAULT;
> +    }

Again, Xen stashes the GVA for this and not the GPA.

  Paul