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").
Just wondering if that is intended (I imagine it will be different with
free page reporting)?
Apart from that looks good to me!
--
Thanks,
David / dhildenb
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