Re: [RFC PATCH 13/21] i386/xen: implement HYPERVISOR_hvm_op

[Philippe Mathieu-Daudé]

On 5/12/22 18:31, David Woodhouse wrote:
> From: Joao Martins <joao.m.martins@oracle.com>
>
> This is when guest queries for support for HVMOP_pagetable_dying.
>
> Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
> Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
> ---
>   target/i386/xen.c | 18 ++++++++++++++++++
>   1 file changed, 18 insertions(+)
>
> diff --git a/target/i386/xen.c b/target/i386/xen.c
> index 5d2d8a7e00..38d4cae3d0 100644
> --- a/target/i386/xen.c
> +++ b/target/i386/xen.c
> @@ -17,6 +17,7 @@
>   
>   #include "standard-headers/xen/version.h"
>   #include "standard-headers/xen/memory.h"
> +#include "standard-headers/xen/hvm/hvm_op.h"
>   
>   #define PAGE_OFFSET    0xffffffff80000000UL
>   #define PAGE_SHIFT     12
> @@ -181,6 +182,20 @@ static int kvm_xen_hcall_memory_op(struct kvm_xen_exit 
> *exit,
>       return err ? HCALL_ERR : 0;
>   }
>   
> +static int kvm_xen_hcall_hvm_op(struct kvm_xen_exit *exit,
> +                                int cmd, uint64_t arg)
> +{
> +    switch (cmd) {
> +    case HVMOP_pagetable_dying: {
> +            exit->u.hcall.result = -ENOSYS;
> +            return 0;
> +        }
> +    }

Could it be helpful to have a trace event here, or log a GUEST_ERROR?

> +    exit->u.hcall.result = -ENOSYS;
> +    return HCALL_ERR;
> +}