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From: "Jan Beulich" <JBeulich@suse.com>
To: Juergen Gross <JGross@suse.com>
Cc: tim@xen.org, sstabellini@kernel.org, wei.liu2@citrix.com,
	George.Dunlap@eu.citrix.com, andrew.cooper3@citrix.com,
	ian.jackson@eu.citrix.com, xen-devel@lists.xen.org,
	julien.grall@arm.com
Subject: Re: [PATCH v3 2/2] xen: add update indicator to vcpu_runstate_info
Date: Fri, 17 Jun 2016 02:03:21 -0600	[thread overview]
Message-ID: <5763CAE902000078000F5ED1@prv-mh.provo.novell.com> (raw)
In-Reply-To: <1466141184-28876-3-git-send-email-jgross@suse.com>

>>> On 17.06.16 at 07:26, <JGross@suse.com> wrote:
> In order to support reading another vcpu's mapped vcpu_runstate_info
> an indicator for an occurring update of the runstate information is
> needed.
> 
> Add the possibility to activate setting this indicator in the highest
> bit of state_entry_time via a vm_assist hypercall. When activated the
> update indicator will be set before the runstate information is
> modified in guest memory and it will be reset after modification is
> done. As state_entry_time is guaranteed to be different after each
> update the guest can detect any update (either in progress or while
> reading the runstate data) by comparing state_entry_time before and
> after reading runstate data: in case the values differ or the update
> indicator was set the data might be inconsistent and should be reread.
> 
> Signed-off-by: Juergen Gross <jgross@suse.com>

Reviewed-by: Jan Beulich <jbeulich@suse.com>

But I'd really like to see some of the explanation why we want this
moved here from the cover letter. This of course can be done while
committing, if no other need for a v4 arises.

Jan


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  reply	other threads:[~2016-06-17  8:03 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-17  5:26 [PATCH v3 0/2] Support consistent reads of mapped vcpu_runstate_info Juergen Gross
2016-06-17  5:26 ` [PATCH v3 1/2] xen/arm: add support for vm_assist hypercall Juergen Gross
2016-06-17  5:26 ` [PATCH v3 2/2] xen: add update indicator to vcpu_runstate_info Juergen Gross
2016-06-17  8:03   ` Jan Beulich [this message]
2016-06-20 17:36   ` Julien Grall

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