On 29.05.20 18:57, Alexander Duyck wrote:
> On Fri, May 29, 2020 at 1:13 AM David Hildenbrand <da...@redhat.com> wrote:
>>
>> On 27.05.20 06:06, Alexander Duyck wrote:
>>> From: Alexander Duyck <alexander.h.du...@linux.intel.com>
>>>
>>> Page poison provides a way for the guest to notify the host that it is
>>> initializing or poisoning freed pages with some specific poison value. As a
>>> result of this we can infer a couple traits about the guest:
>>>
>>> 1. Free pages will contain a specific pattern within the guest.
>>> 2. Modifying free pages from this value may cause an error in the guest.
>>> 3. Pages will be immediately written to by the driver when deflated.
>>>
>>> There are currently no existing features that make use of this data. In the
>>> upcoming feature free page reporting we will need to make use of this to
>>> identify if we can evict pages from the guest without causing data
>>> corruption.
>>>
>>> Add documentation for the page poison feature describing the basic
>>> functionality and requirements.
>>>
>>> Signed-off-by: Alexander Duyck <alexander.h.du...@linux.intel.com>
>>> ---
>>> conformance.tex | 2 ++
>>> content.tex | 59
>>> +++++++++++++++++++++++++++++++++++++++++++++++++++----
>>> 2 files changed, 57 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/conformance.tex b/conformance.tex
>>> index b6fdec090383..4ed9d62e8088 100644
>>> --- a/conformance.tex
>>> +++ b/conformance.tex
>>> @@ -149,6 +149,7 @@ \section{Conformance Targets}\label{sec:Conformance /
>>> Conformance Targets}
>>> \item \ref{drivernormative:Device Types / Memory Balloon Device / Feature
>>> bits}
>>> \item \ref{drivernormative:Device Types / Memory Balloon Device / Device
>>> Operation}
>>> \item \ref{drivernormative:Device Types / Memory Balloon Device / Device
>>> Operation / Memory Statistics}
>>> +\item \ref{drivernormative:Device Types / Memory Balloon Device / Device
>>> Operation / Page Poison}
>>> \end{itemize}
>>>
>>> \conformance{\subsection}{SCSI Host Driver
>>> Conformance}\label{sec:Conformance / Driver Conformance / SCSI Host Driver
>>> Conformance}
>>> @@ -331,6 +332,7 @@ \section{Conformance Targets}\label{sec:Conformance /
>>> Conformance Targets}
>>> \item \ref{devicenormative:Device Types / Memory Balloon Device / Feature
>>> bits}
>>> \item \ref{devicenormative:Device Types / Memory Balloon Device / Device
>>> Operation}
>>> \item \ref{devicenormative:Device Types / Memory Balloon Device / Device
>>> Operation / Memory Statistics}
>>> +\item \ref{devicenormative:Device Types / Memory Balloon Device / Device
>>> Operation / Page Poison}
>>> \end{itemize}
>>>
>>> \conformance{\subsection}{SCSI Host Device
>>> Conformance}\label{sec:Conformance / Device Conformance / SCSI Host Device
>>> Conformance}
>>> diff --git a/content.tex b/content.tex
>>> index 91735e3eb018..4a0ab90260ff 100644
>>> --- a/content.tex
>>> +++ b/content.tex
>>> @@ -5019,6 +5019,9 @@ \subsection{Feature bits}\label{sec:Device Types /
>>> Memory Balloon Device / Featu
>>> memory statistics is present.
>>> \item[VIRTIO_BALLOON_F_DEFLATE_ON_OOM (2) ] Deflate balloon on
>>> guest out of memory condition.
>>> +\item[ VIRTIO_BALLOON_F_PAGE_POISON(4) ] A hint to the device, that the
>>> driver
>>> + will immediately write \field{poison_val} to pages after deflating
>>> them.
>>> + Configuration field \field{poison_val} is valid.
>>>
>>
>> Here we have "that the driver will immediately" ...
>>
>> But we never document that in form of a normative statement (e.g., "The
>> driver MUST initialize pages with \field{poison_val} after deflating").
>
> I'm pretty sure we did document that. In the normative statement for
> the driver below we have:
> +The driver MUST initialize the deflated pages with \field{poison_val} when
> +they are reused by the driver.
>
Doh! I think I missed that somehow
Reviewed-by: David Hildenbrand <da...@redhat.com>
Thanks!
--
Thanks,
David / dhildenb
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