From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: virtio-comment-return-639-cohuck=redhat.com@lists.oasis-open.org Sender: List-Post: List-Help: List-Unsubscribe: List-Subscribe: From: "Dr. David Alan Gilbert (git)" Date: Fri, 22 Feb 2019 11:54:32 +0000 Message-Id: <20190222115433.7160-3-dgilbert@redhat.com> In-Reply-To: <20190222115433.7160-1-dgilbert@redhat.com> References: <20190222115433.7160-1-dgilbert@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Subject: [virtio-comment] [PATCH v2 2/3] shared memory: Define PCI capability To: virtio-comment@lists.oasis-open.org, virtio-dev@lists.oasis-open.org Cc: stefanha@redhat.com, cohuck@redhat.com List-ID: From: "Dr. David Alan Gilbert" Define the PCI capability used for enumerating shared memory regions. Signed-off-by: Dr. David Alan Gilbert Reviewed-by: Stefan Hajnoczi --- content.tex | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) diff --git a/content.tex b/content.tex index 3dd504c..9838208 100644 --- a/content.tex +++ b/content.tex @@ -688,6 +688,8 @@ The fields are interpreted as follows: #define VIRTIO_PCI_CAP_DEVICE_CFG 4 /* PCI configuration access */ #define VIRTIO_PCI_CAP_PCI_CFG 5 +/* Shared memory region */ +#define VIRTIO_PCI_CAP_SHARED_MEMORY_CFG 8 \end{lstlisting} Any other value is reserved for future use. @@ -1052,6 +1054,41 @@ any device type which has a device-specific configuration. The \field{offset} for the device-specific configuration MUST be 4-byte aligned. +\subsubsection{Shared memory capability}\label{sec:Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / Shared memory capability} + +Shared memory regions \ref{sec:Basic Facilities of a Virtio +Device / Shared Memory Regions} are enumerated on the PCI transport +as a sequence of VIRTIO_PCI_CAP_SHARED_MEMORY_CFG capabilities, one per region. + +The capability is immediately followed by an additional field like so: + +\begin{lstlisting} +struct virtio_pci_shm_cap { + struct virtio_pci_cap cap; + u32 offset_hi; + u32 length_hi; + u8 id; +}; +\end{lstlisting} + +Given that the \field{cap.length} and \field{cap.offset} fields +are only 32 bit, the additional \field{offset_hi} and \field {length_hi} +fields provide the most significant 32 bits of a total 64 bit offset and +length within the bar specified by \field{cap.bar}. \field{id} +uniquely identifies the given shared memory region using a device +specific identifier. + +While most capabilities can not be repeated, multiple +VIRTIO_PCI_CAP_SHARED_MEMORY_CFG capabilities are allowed as long +as the \field{id} is unique. + +\devicenormative{\paragraph}{Device-specific configuration}{Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / Shared memory capability} + +The region defined by the combination of the offsets and length +fields MUST be contained within the declared bar. + +The \field{id} MUST be unique for any one device instance. + \subsubsection{PCI configuration access capability}\label{sec:Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / PCI configuration access capability} The VIRTIO_PCI_CAP_PCI_CFG capability -- 2.20.1 This publicly archived list offers a means to provide input to the OASIS Virtual I/O Device (VIRTIO) TC. In order to verify user consent to the Feedback License terms and to minimize spam in the list archive, subscription is required before posting. Subscribe: virtio-comment-subscribe@lists.oasis-open.org Unsubscribe: virtio-comment-unsubscribe@lists.oasis-open.org List help: virtio-comment-help@lists.oasis-open.org List archive: https://lists.oasis-open.org/archives/virtio-comment/ Feedback License: https://www.oasis-open.org/who/ipr/feedback_license.pdf List Guidelines: https://www.oasis-open.org/policies-guidelines/mailing-lists Committee: https://www.oasis-open.org/committees/virtio/ Join OASIS: https://www.oasis-open.org/join/