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Re: [PATCH v1 2/2] domctl: Handle some of XEN_DOMCTL_shadow_op without the domctl lock
- To: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Mon, 15 Jun 2026 16:23:54 +0200
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- Cc: Roger Pau Monné <roger.pau@xxxxxxxxxx>, Teddy Astie <teddy.astie@xxxxxxxxxx>, Anthony PERARD <anthony.perard@xxxxxxxxxx>, Michal Orzel <michal.orzel@xxxxxxx>, Julien Grall <julien@xxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, "Daniel P. Smith" <dpsmith@xxxxxxxxxxxxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
- Delivery-date: Mon, 15 Jun 2026 14:24:07 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 09.06.2026 17:15, Ross Lagerwall wrote:
> --- a/xen/common/domctl.c
> +++ b/xen/common/domctl.c
> @@ -559,6 +559,18 @@ long do_domctl(XEN_GUEST_HANDLE_PARAM(xen_domctl_t)
> u_domctl)
> ret = arch_do_domctl(op, d, u_domctl);
> goto domctl_out_unlock_domonly;
>
> + case XEN_DOMCTL_shadow_op:
> + if ( op->u.shadow_op.op == XEN_DOMCTL_SHADOW_OP_CLEAN ||
> + op->u.shadow_op.op == XEN_DOMCTL_SHADOW_OP_PEEK )
> + {
> + ret = xsm_domctl(XSM_OTHER, d, op);
> + if ( ret )
> + goto domctl_out_unlock_domonly;
> +
> + ret = arch_do_domctl(op, d, u_domctl);
> + goto domctl_out_unlock_domonly;
> + }
> + fallthrough;
> default:
> /* Everything else handled further down. */
> break;
I understand this did already go in as is, yet I have to admit I'm surprised
that it was ack-ed in this shape. For "domctl: handle XEN_DOMCTL_getvcpuinfo
without acquiring domctl lock" [1] it was specifically requested that I
introduce yet another switch(), to limit the number of xsm_domctl() call
sites. IOW I think subsequently this case block wants moving into the new
switch() that the referenced patch introduces.
Jan
[1] https://lists.xen.org/archives/html/xen-devel/2026-06/msg00857.html
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