Messages in this thread | | | Date | Tue, 22 Aug 2023 12:13:20 +0200 | Subject | Re: [PATCH V5] xen: privcmd: Add support for irqfd | From | Juergen Gross <> |
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On 22.08.23 11:45, Viresh Kumar wrote: > Xen provides support for injecting interrupts to the guests via the > HYPERVISOR_dm_op() hypercall. The same is used by the Virtio based > device backend implementations, in an inefficient manner currently. > > Generally, the Virtio backends are implemented to work with the Eventfd > based mechanism. In order to make such backends work with Xen, another > software layer needs to poll the Eventfds and raise an interrupt to the > guest using the Xen based mechanism. This results in an extra context > switch. > > This is not a new problem in Linux though. It is present with other > hypervisors like KVM, etc. as well. The generic solution implemented in > the kernel for them is to provide an IOCTL call to pass the interrupt > details and eventfd, which lets the kernel take care of polling the > eventfd and raising of the interrupt, instead of handling this in user > space (which involves an extra context switch). > > This patch adds support to inject a specific interrupt to guest using > the eventfd mechanism, by preventing the extra context switch. > > Inspired by existing implementations for KVM, etc.. > > Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Juergen Gross <jgross@suse.com>
Juergen
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