Re: [PATCH v2 09/17] xen/dom0less: store xenstore event channel in page

[Juergen Gross <jgross@xxxxxxxx>]

On 16.07.25 23:14, Jason Andryuk wrote:
> Write the associated event channel into the xenstore page so xenstored
> can read it.  xenstored can map the grant by the reserved grant table
> entry, and then read out the event channel and bind it.  This eliminates
> the need for an additional mechanism to discover the event channel.
>
> Signed-off-by: Jason Andryuk <jason.andryuk@xxxxxxx>
> ---
>   xen/common/device-tree/dom0less-build.c | 7 +++++++
>   1 file changed, 7 insertions(+)
>
> diff --git a/xen/common/device-tree/dom0less-build.c 
> b/xen/common/device-tree/dom0less-build.c
> index a2789e3bdf..284139bf14 100644
> --- a/xen/common/device-tree/dom0less-build.c
> +++ b/xen/common/device-tree/dom0less-build.c
> @@ -26,6 +26,7 @@
>   #include <public/io/xs_wire.h>
>   
>   #include <asm/dom0less-build.h>
> +#include <asm/guest_access.h>
>   #include <asm/setup.h>
>   
>   #include <xen/static-memory.h>
> @@ -126,8 +127,14 @@ static void __init initialize_domU_xenstore(void)
>   
>           if ( gfn != XENSTORE_PFN_LATE_ALLOC && IS_ENABLED(CONFIG_GRANT_TABLE) )
>           {
> +            evtchn_port_t port = d->arch.hvm.params[HVM_PARAM_STORE_EVTCHN];
> +            paddr_t evtchn_gaddr = gfn_to_gaddr(_gfn(gfn)) +
> +                offsetof(struct xenstore_domain_interface, evtchn_port);
> +
>               ASSERT(gfn < UINT32_MAX);
>               gnttab_seed_entry(d, GNTTAB_RESERVED_XENSTORE, xs_domid, gfn);
> +            access_guest_memory_by_gpa(d, evtchn_gaddr, &port, sizeof(port),
> +                                       true /* is_write */);
I couldn't find access_guest_memory_by_gpa() for x86. I think you either need to
introduce it for all archs, or you need to handle this differently.


Juergen

Attachment: OpenPGP_0xB0DE9DD628BF132F.asc
Description: OpenPGP public key

Attachment: OpenPGP_signature.asc
Description: OpenPGP digital signature