From: Corneliu ZUZU <czuzu@bitdefender.com>
To: Tamas K Lengyel <tamas@tklengyel.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>,
Jan Beulich <jbeulich@suse.com>,
Razvan Cojocaru <rcojocaru@bitdefender.com>,
Xen-devel <xen-devel@lists.xen.org>
Subject: Re: [PATCH 2/7] vm-event: VM_EVENT_FLAG_DENY requires VM_EVENT_FLAG_VCPU_PAUSED
Date: Fri, 17 Jun 2016 11:43:59 +0300 [thread overview]
Message-ID: <a5f6d02d-004b-be40-9479-fcb41e6ff18b@bitdefender.com> (raw)
In-Reply-To: <CABfawh=pst-=2c0US6ZFqbxn4++kwgk5309QEud4TRr=k=kY4Q@mail.gmail.com>
On 6/16/2016 7:11 PM, Tamas K Lengyel wrote:
> On Thu, Jun 16, 2016 at 8:07 AM, Corneliu ZUZU <czuzu@bitdefender.com> wrote:
>> For VM_EVENT_FLAG_DENY to work, the vcpu must be paused (sync = 1) until the
>> vm-event is handled. A vm-event response having VM_EVENT_FLAG_DENY flag set
>> should also set the VM_EVENT_FLAG_VCPU_PAUSED flag. Enforce that in
>> vm_event_register_write_resume().
> Well, the problem with this is that the user can set the VCPU_PAUSED
> flag any time it wants. It can happen that Xen hasn't paused the vCPU
> but the user still sends that flag, in which case the unpause the flag
> induces will not actually do anything. You should also check if the
> vCPU is in fact paused rather then just relying on this flag.
>
> Tamas
>
Right, I actually meant to take a second look over that.
I see a situation like that was taken into account in
vm_event_vcpu_unpause (comment "prevent underflow of the vcpu pause count.")
How can I check for vcpu pause here?
Thanks,
Corneliu.
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next prev parent reply other threads:[~2016-06-17 8:43 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-16 14:04 [PATCH 0/7] vm-event: Implement ARM support for control-register writes Corneliu ZUZU
2016-06-16 14:06 ` [PATCH 1/7] minor (formatting) fixes Corneliu ZUZU
2016-06-16 14:24 ` Jan Beulich
2016-06-16 19:19 ` Corneliu ZUZU
2016-06-17 7:06 ` Jan Beulich
2016-06-17 10:46 ` Corneliu ZUZU
2016-06-16 16:02 ` Tamas K Lengyel
2016-06-17 8:33 ` Corneliu ZUZU
2016-06-17 8:36 ` Razvan Cojocaru
2016-06-17 9:29 ` Andrew Cooper
2016-06-17 9:35 ` Jan Beulich
2016-06-17 9:33 ` Jan Beulich
2016-06-17 9:36 ` Razvan Cojocaru
2016-06-17 9:40 ` Jan Beulich
2016-06-17 9:42 ` Razvan Cojocaru
2016-06-17 19:05 ` Tamas K Lengyel
2016-06-16 14:07 ` [PATCH 2/7] vm-event: VM_EVENT_FLAG_DENY requires VM_EVENT_FLAG_VCPU_PAUSED Corneliu ZUZU
2016-06-16 16:11 ` Tamas K Lengyel
2016-06-17 8:43 ` Corneliu ZUZU [this message]
2016-06-21 11:26 ` Corneliu ZUZU
2016-06-21 15:09 ` Tamas K Lengyel
2016-06-22 8:34 ` Corneliu ZUZU
2016-06-16 14:08 ` [PATCH 3/7] vm-event: introduce vm_event_vcpu_enter Corneliu ZUZU
2016-06-16 14:51 ` Jan Beulich
2016-06-16 20:10 ` Corneliu ZUZU
2016-06-16 20:33 ` Razvan Cojocaru
2016-06-17 10:41 ` Corneliu ZUZU
2016-06-17 7:17 ` Jan Beulich
2016-06-17 11:13 ` Corneliu ZUZU
2016-06-17 11:27 ` Jan Beulich
2016-06-17 12:13 ` Corneliu ZUZU
2016-06-16 16:17 ` Tamas K Lengyel
2016-06-17 9:19 ` Corneliu ZUZU
2016-06-17 8:55 ` Julien Grall
2016-06-17 11:40 ` Corneliu ZUZU
2016-06-17 13:22 ` Julien Grall
2016-06-16 14:09 ` [PATCH 4/7] vm-event/x86: use vm_event_vcpu_enter properly Corneliu ZUZU
2016-06-16 15:00 ` Jan Beulich
2016-06-16 20:20 ` Corneliu ZUZU
2016-06-17 7:20 ` Jan Beulich
2016-06-17 11:23 ` Corneliu ZUZU
2016-06-16 16:27 ` Tamas K Lengyel
2016-06-17 9:24 ` Corneliu ZUZU
2016-06-16 14:10 ` [PATCH 5/7] x86: replace monitor_write_data.do_write with enum Corneliu ZUZU
2016-06-16 14:12 ` [PATCH 6/7] vm-event/arm: move hvm_event_cr->common vm_event_monitor_cr Corneliu ZUZU
2016-06-16 15:16 ` Jan Beulich
2016-06-17 8:25 ` Corneliu ZUZU
2016-06-17 8:38 ` Jan Beulich
2016-06-17 11:31 ` Corneliu ZUZU
2016-06-21 7:08 ` Corneliu ZUZU
2016-06-21 7:20 ` Jan Beulich
2016-06-21 15:22 ` Tamas K Lengyel
2016-06-22 6:33 ` Jan Beulich
2016-06-16 16:55 ` Tamas K Lengyel
2016-06-17 10:37 ` Corneliu ZUZU
2016-06-16 14:13 ` [PATCH 7/7] vm-event/arm: implement support for control-register write vm-events Corneliu ZUZU
2016-06-16 14:26 ` Julien Grall
2016-06-16 19:24 ` Corneliu ZUZU
2016-06-16 21:28 ` Julien Grall
2016-06-17 11:46 ` Corneliu ZUZU
2016-06-16 16:49 ` Julien Grall
2016-06-17 10:36 ` Corneliu ZUZU
2016-06-17 13:18 ` Julien Grall
2016-06-22 16:35 ` Corneliu ZUZU
2016-06-22 17:17 ` Julien Grall
2016-06-22 18:39 ` Corneliu ZUZU
2016-06-22 19:37 ` Corneliu ZUZU
2016-06-22 19:41 ` Julien Grall
2016-06-23 5:31 ` Corneliu ZUZU
2016-06-23 5:49 ` Corneliu ZUZU
2016-06-23 11:11 ` Julien Grall
2016-06-24 9:32 ` Corneliu ZUZU
2016-06-23 11:00 ` Julien Grall
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