xen-devel.lists.xenproject.org archive mirror
 help / color / mirror / Atom feed
From: Corneliu ZUZU <czuzu@bitdefender.com>
To: Xen-devel <xen-devel@lists.xen.org>
Cc: Tamas K Lengyel <tamas@tklengyel.com>,
	Stefano Stabellini <stefano.stabellini@citrix.com>,
	Razvan Cojocaru <rcojocaru@bitdefender.com>,
	Jan Beulich <jbeulich@suse.com>
Subject: Scheduler/hypervisor traps, vm_event_vcpu_pause - some details on how they work?
Date: Mon, 14 Mar 2016 08:51:41 +0200	[thread overview]
Message-ID: <56E65F7D.10708@bitdefender.com> (raw)

Hey all,

I'm trying to add a vm-event function that would execute just before a 
vCPU resumes execution. To do this, I need to know precisely how and 
when this happens.
I've been browsing the codebase to try and gain some insight on the 
matter, but I still need some clarifications as parts of it are not so 
straight-forward.

Currently my understanding is that a vCPU can be entered in 3 ways:

1) The first entry, when the vCPU is first created. On ARM, the PC of 
the vCPU is set to continue_new_vcpu.
     Q1. How does this happen on X86?

2) After a hypervisor trap (X86 VMENTER/ARM ERET).
     Q2. How does pausing of the current vCPU (vm_event_vcpu_pause) 
work, specifically where does the context switch to another vCPU happen? 
Is it reentered through the below mentioned scheduling functions?
     Q3. Can we resume on another vCPU than the one that trapped if it 
wasn't paused?
     Q4. Can a hypervisor trap be interrupted by a scheduling operation?

3) Scheduler interrupt -> functions context_switch/continue_running.

Q5. Are these 3 the only ways a vCPU can be entered?

Thank you very much,
Corneliu.

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
http://lists.xen.org/xen-devel

                 reply	other threads:[~2016-03-14  6:51 UTC|newest]

Thread overview: [no followups] expand[flat|nested]  mbox.gz  Atom feed

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=56E65F7D.10708@bitdefender.com \
    --to=czuzu@bitdefender.com \
    --cc=jbeulich@suse.com \
    --cc=rcojocaru@bitdefender.com \
    --cc=stefano.stabellini@citrix.com \
    --cc=tamas@tklengyel.com \
    --cc=xen-devel@lists.xen.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).