Re: [XEN PATCH v1 1/1] x86/domctl: add gva_to_gfn command

[Ковалёв Сергей <valor@xxxxxxx>]

Thanks to all for suggestions and notes.

Though as Andrew Cooper noticed current approach is too over simplified.
As Tams K Lengyel noticed the effect could be too negligible and some
OS specific logic should be present.

So as for today we could drop the patch.

20.03.2023 19:32, Ковалёв Сергей пишет:
> gva_to_gfn command used for fast address translation in LibVMI project.
> With such a command it is possible to perform address translation in
> single call instead of series of queries to get every page table.
>
> Thanks to Dmitry Isaykin for involvement.
>
> Signed-off-by: Sergey Kovalev <valor@xxxxxxx>
>
> ---
> Cc: Jan Beulich <jbeulich@xxxxxxxx>
> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Cc: "Roger Pau Monné" <roger.pau@xxxxxxxxxx>
> Cc: Wei Liu <wl@xxxxxxx>
> Cc: George Dunlap <george.dunlap@xxxxxxxxxx>
> Cc: Julien Grall <julien@xxxxxxx>
> Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> Cc: Tamas K Lengyel <tamas@xxxxxxxxxxxxx>
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx
> ---
>
> ---
>   xen/arch/x86/domctl.c       | 17 +++++++++++++++++
>   xen/include/public/domctl.h | 13 +++++++++++++
>   2 files changed, 30 insertions(+)
>
> diff --git a/xen/arch/x86/domctl.c b/xen/arch/x86/domctl.c
> index 2118fcad5d..0c9706ea0a 100644
> --- a/xen/arch/x86/domctl.c
> +++ b/xen/arch/x86/domctl.c
> @@ -1364,6 +1364,23 @@ long arch_do_domctl(
>               copyback = true;
>           break;
>
> +    case XEN_DOMCTL_gva_to_gfn:
> +    {
> +        uint64_t ga = domctl->u.gva_to_gfn.addr;
> +        uint64_t cr3 = domctl->u.gva_to_gfn.cr3;
> +        struct vcpu* v = d->vcpu[0];
> +        uint32_t pfec = PFEC_page_present;
> +        unsigned int page_order;
> +
> +        uint64_t gfn = paging_ga_to_gfn_cr3(v, cr3, ga, &pfec, 
> &page_order);
> +        domctl->u.gva_to_gfn.addr = gfn;
> +        domctl->u.gva_to_gfn.page_order = page_order;
> +        if ( __copy_to_guest(u_domctl, domctl, 1) )
> +            ret = -EFAULT;
> +
> +        break;
> +    }
> +
>       default:
>           ret = -ENOSYS;
>           break;
> diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h
> index 51be28c3de..628dfc68fd 100644
> --- a/xen/include/public/domctl.h
> +++ b/xen/include/public/domctl.h
> @@ -948,6 +948,17 @@ struct xen_domctl_paging_mempool {
>       uint64_aligned_t size; /* Size in bytes. */
>   };
>
> +/*
> + * XEN_DOMCTL_gva_to_gfn.
> + *
> + * Get the guest virtual to guest physicall address translated.
> + */
> +struct xen_domctl_gva_to_gfn {
> +    uint64_aligned_t addr;
> +    uint64_aligned_t cr3;
> +    uint64_aligned_t page_order;
> +};
> +
>   #if defined(__i386__) || defined(__x86_64__)
>   struct xen_domctl_vcpu_msr {
>       uint32_t         index;
> @@ -1278,6 +1289,7 @@ struct xen_domctl {
>   #define XEN_DOMCTL_vmtrace_op                    84
>   #define XEN_DOMCTL_get_paging_mempool_size       85
>   #define XEN_DOMCTL_set_paging_mempool_size       86
> +#define XEN_DOMCTL_gva_to_gfn                    87
>   #define XEN_DOMCTL_gdbsx_guestmemio            1000
>   #define XEN_DOMCTL_gdbsx_pausevcpu             1001
>   #define XEN_DOMCTL_gdbsx_unpausevcpu           1002
> @@ -1340,6 +1352,7 @@ struct xen_domctl {
>           struct xen_domctl_vuart_op          vuart_op;
>           struct xen_domctl_vmtrace_op        vmtrace_op;
>           struct xen_domctl_paging_mempool    paging_mempool;
> +        struct xen_domctl_gva_to_gfn        gva_to_gfn;
>           uint8_t                             pad[128];
>       } u;
>   };
--
Best regards,
Sergey Kovalev