On 9/6/2023 4:32 PM, Michael S. Tsirkin wrote:
On Wed, Sep 06, 2023 at 04:16:37PM +0800, Zhu Lingshan wrote:
This patch adds two new le16 fields to common configuration structure
to support VIRTIO_F_QUEUE_STATE in PCI transport layer.
Signed-off-by: Zhu Lingshan <lingshan....@intel.com>
I do not see why this would be pci specific at all.
It is just the implementation is transport specific.
But besides I thought work on live migration will use
admin queue. This was explicitly one of the motivators.
I assume this straight forward solution can work.
Poking at the device from the driver to migrate it
is not going to work if the driver lives within guest.
The hypervisor can still set SUSPEND and do other stuffs like
collecting dirty pages.
The process should be freeze the guest first, then suspend the device.
---
transport-pci.tex | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/transport-pci.tex b/transport-pci.tex
index a5c6719..3161519 100644
--- a/transport-pci.tex
+++ b/transport-pci.tex
@@ -325,6 +325,10 @@ \subsubsection{Common configuration structure
layout}\label{sec:Virtio Transport
/* About the administration virtqueue. */
le16 admin_queue_index; /* read-only for driver */
le16 admin_queue_num; /* read-only for driver */
+
+ /* Virtqueue state */
+ le16 queue_avail_state; /* read-write */
+ le16 queue_used_state; /* read-write */
};
\end{lstlisting}
@@ -428,6 +432,17 @@ \subsubsection{Common configuration structure layout}\label{sec:Virtio Transport
The value 0 indicates no supported administration virtqueues.
This field is valid only if VIRTIO_F_ADMIN_VQ has been
negotiated.
+
+\item[\field{queue_avail_state}]
+ This field is valid only if VIRTIO_F_QUEUE_STATE has been
+ negotiated. The driver sets and gets the available state of
+ the virtqueue here (see \ref{sec:Virtqueues / Virtqueue State}).
+
+\item[\field{queue_used_state}]
+ This field is valid only if VIRTIO_F_QUEUE_STATE has been
+ negotiated. The driver sets and gets the used state of the
+ virtqueue here (see \ref{sec:Virtqueues / Virtqueue State}).
+
\end{description}
\devicenormative{\paragraph}{Common configuration structure layout}{Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / Common configuration structure layout}
@@ -488,6 +503,9 @@ \subsubsection{Common configuration structure
layout}\label{sec:Virtio Transport
present either a value of 0 or a power of 2 in
\field{queue_size}.
+If VIRTIO_F_QUEUE_STATE has not been negotiated, the device MUST ignore
+any accesses to \field{queue_avail_state} and \field{queue_used_state}.
+
If VIRTIO_F_ADMIN_VQ has been negotiated, the value
\field{admin_queue_index} MUST be equal to, or bigger than
\field{num_queues}; also, \field{admin_queue_num} MUST be
--
2.35.3
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