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Subject: [PATCH v3 2/9] virtio-iommu: Add INVALIDATE request
Add a request that invalidates mappings of a domain attached with table.
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
device-types/iommu/description.tex | 165 ++++++++++++++++++++++
device-types/iommu/device-conformance.tex | 1 +
device-types/iommu/driver-conformance.tex | 1 +
3 files changed, 167 insertions(+)
diff --git a/device-types/iommu/description.tex b/device-types/iommu/description.tex
index edf8811..c20897a 100644
--- a/device-types/iommu/description.tex
+++ b/device-types/iommu/description.tex
@@ -180,6 +180,7 @@ \subsection{Device operations}\label{sec:Device Types / IOMMU Device / Device op
#define VIRTIO_IOMMU_T_UNMAP 4
#define VIRTIO_IOMMU_T_PROBE 5
#define VIRTIO_IOMMU_T_ATTACH_TABLE 6
+#define VIRTIO_IOMMU_T_INVALIDATE 7
\end{lstlisting}
A few general-purpose status codes are defined here.
@@ -712,6 +713,170 @@ \subsubsection{UNMAP request}\label{sec:Device Types / IOMMU Device / Device ope
mapping, then the device SHOULD remove all mappings affected by the range
and set the request \field{status} to VIRTIO_IOMMU_S_OK.
+\subsubsection{INVALIDATE request}\label{sec:Device Types / IOMMU Device / Device operations / INVALIDATE request}
+
+\begin{lstlisting}
+struct virtio_iommu_req_invalidate {
+ struct virtio_iommu_req_head head;
+ u8 scope;
+ u8 caches;
+ le16 flags;
+ le32 domain;
+ le32 pasid;
+ le64 id;
+ le64 address;
+ le64 nr_pages;
+ u8 page_size;
+ u8 reserved[19];
+ struct virtio_iommu_req_tail tail;
+};
+
+#define VIRTIO_IOMMU_INVAL_S_DOMAIN 1
+#define VIRTIO_IOMMU_INVAL_S_PASID 2
+#define VIRTIO_IOMMU_INVAL_S_ADDRESS 3
+
+#define VIRTIO_IOMMU_INVAL_C_PASID (1 << 0)
+#define VIRTIO_IOMMU_INVAL_C_TLB (1 << 1)
+
+#define VIRTIO_IOMMU_INVAL_F_LEAF (1 << 0)
+#define VIRTIO_IOMMU_INVAL_F_PASID (1 << 1)
+#define VIRTIO_IOMMU_INVAL_F_ID (1 << 2)
+#define VIRTIO_IOMMU_INVAL_F_GLOBAL (1 << 3)
+\end{lstlisting}
+
+Invalidate a mapping or configuration. When using PASID or page
+tables, the driver sends an INVALIDATE request to signal changes
+to table entries that might have been cached by the device, and
+to synchronize with table walkers.
+
+Field \field{scope} specifies which entries to invalidate:
+\begin{description}
+ \item[VIRTIO_IOMMU_INVAL_S_DOMAIN] invalidates all cached
+ entries for the given \field{domain}.
+ \item[VIRTIO_IOMMU_INVAL_S_PASID] invalidates all cached
+ entries for the given \field{domain} and \field{pasid}.
+ \item[VIRTIO_IOMMU_INVAL_S_ADDRESS] invalidates all cached
+ entries for the given \field{domain}, \field{pasid} and
+ virtual address range.
+\end{description}
+
+Field \field{caches} specifies which caches to invalidate:
+\begin{description}
+ \item[VIRTIO_IOMMU_INVAL_C_PASID] Invalidate entries cached
+ from the PASID table.
+ \item[VIRTIO_IOMMU_INVAL_C_TLB] Invalidate entries from the
+ Translation Lookaside Buffers (TLBs), including device TLBs
+ such as those implemented with the PCIe ATS extension.
+\end{description}
+
+For example, when the driver removes a mapping from a table
+attached to the \field{domain}, it sends an INVALIDATE request
+for \field{scope} ADDRESS and \field{caches} TLB. To invalidate
+the whole address space the driver sets the \field{scope} to
+DOMAIN, or to PASID when using a PASID table. When removing a
+page directory from a PASID table entry, the driver sends an
+INVALIDATE request with \field{scope} PASID, and all
+\field{caches} flags set.
+
+Field \field{flags} specifies additional information:
+\begin{description}
+ \item[VIRTIO_IOMMU_INVAL_F_LEAF] Only invalidate TLB entries
+ cached from leaf table entries.
+ \item[VIRTIO_IOMMU_INVAL_F_PASID] The \field{pasid} field is
+ valid.
+ \item[VIRTIO_IOMMU_INVAL_F_ID] The \field{id} field is valid.
+ \item[VIRTIO_IOMMU_INVAL_F_GLOBAL] In addition to TLB entries
+ targeted by the invalidation, also invalidate global entries.
+ For example PCIe ATS may create global entries if the IOMMU
+ sets the Global mapping bit in a Translation Completion.
+\end{description}
+
+Use of field \field{id} is specific to the table format. Some
+formats use only the PASID to identify address spaces within a
+domain, others use a separate ID for TLB entries.
+
+For a \field{scope} of VIRTIO_IOMMU_INVAL_S_ADDRESS, the
+invalidation affects the range of virtual addresses of size
+$\field{nr\_pages} \times 2^\field{page\_size}$, starting at
+\field{address}. Specifying the range size this way allows the
+device to efficiently remove TLB entries. For example a page
+table format could allow a 2MiB range to be mapped with either
+512 4KiB pages, or a single 2MiB block. In the latter case a
+single TLB entry is used, so the driver specifies a
+\field{page_size} of 21 and the device does not need to iterate
+over all 4KiB multiples to invalidate the range.
+
+The following table describes valid \field{caches}, \field{flags}
+and fields for each \field{scope}:
+
+\begin{tabular}{|l|c|c|c|}
+\hline
+ \field{scope} & DOMAIN & PASID & ADDRESS \\
+\hline
+ \field{caches} & PASID, TLB & PASID, TLB & TLB \\
+ \field{flags} & ID & LEAF, PASID, ID & LEAF, PASID, ID, GLOBAL \\
+ \field{domain} & Y & Y & Y \\
+ \field{pasid} & N & Y & Y \\
+ \field{id} & Y & Y & Y \\
+ \field{address} & N & N & Y \\
+ \field{nr_pages} & N & N & Y \\
+ \field{page_size} & N & N & Y \\
+\hline
+\end{tabular}
+
+When using a PASID table, an invalidation of \field{scope}
+PASID or ADDRESS without VIRTIO_IOMMU_INVAL_F_PASID targets cache
+entries that were created by DMA transactions without PASID.
+Depending on the hardware implementation, this may behave in the
+same way as an invalidation of \field{scope} DOMAIN, clearing all
+cached entries including those with PASID. Notably, it is the
+behavior specified by the PCIe ATS extension.
+
+\devicenormative{\paragraph}{INVALIDATE request}{Device Types / IOMMU Device / Device operations / INVALIDATE request}
+
+After handling an INVALIDATE request, the device SHOULD NOT let
+endpoints attached to \field{domain} access virtual address in
+the invalidated range, unless the range is valid in the table
+attached to the \field{domain}. In other words, the device SHOULD
+access the virtual address through the attached tables instead of
+a cache.
+
+For a \field{scope} of VIRTIO_IOMMU_INVAL_S_DOMAIN, the device
+SHOULD ignore fields \field{pasid}, \field{address},
+\field{nr_pages} and \field{page_size}.
+
+For a \field{scope} of VIRTIO_IOMMU_INVAL_S_PASID, the device
+SHOULD ignore fields \field{address}, \field{nr_pages},
+\field{page_size},
+
+If no cache entry exist for the given parameters, the device
+SHOULD set the \field{status} field to VIRTIO_IOMMU_S_OK. In
+other words, spurious invalidations are allowed.
+
+The device MAY invalidate more entries and caches than requested,
+and MAY ignore flag VIRTIO_IOMMU_INVAL_F_LEAF. Over-invalidation
+is allowed, but under-invalidation is not.
+
+\drivernormative{\paragraph}{INVALIDATE request}{Device Types / IOMMU Device / Device operations / INVALIDATE request}
+
+\field{domain} MUST have been created with an ATTACH_TABLE
+request.
+
+For a \field{scope} of VIRTIO_IOMMU_INVAL_S_DOMAIN, the driver
+SHOULD set fields \field{pasid}, \field{address},
+\field{nr_pages} and \field{page_size} to zero.
+
+For a \field{scope} of VIRTIO_IOMMU_INVAL_S_PASID, the driver
+SHOULD set fields \field{address}, \field{nr_pages},
+\field{page_size} to zero.
+
+An invalidation with \field{scope} VIRTIO_IOMMU_INVAL_S_PASID or
+VIRTIO_IOMMU_INVAL_S_ADDRESS that targets cache entries created
+by transactions with PASID SHOULD have a valid \field{pasid} field,
+not solely a valid \field{id} field. This is because a platform can
+enable device caches such as PCIe ATS implicitly, requiring a PASID in
+the invalidation.
+
\subsubsection{PROBE request}\label{sec:Device Types / IOMMU Device / Device operations / PROBE request}
If the VIRTIO_IOMMU_F_PROBE feature bit is present, the driver sends a
diff --git a/device-types/iommu/device-conformance.tex b/device-types/iommu/device-conformance.tex
index 3c71354..d6ce69b 100644
--- a/device-types/iommu/device-conformance.tex
+++ b/device-types/iommu/device-conformance.tex
@@ -11,6 +11,7 @@
\item \ref{devicenormative:Device Types / IOMMU Device / Device operations / DETACH request}
\item \ref{devicenormative:Device Types / IOMMU Device / Device operations / MAP request}
\item \ref{devicenormative:Device Types / IOMMU Device / Device operations / UNMAP request}
+\item \ref{devicenormative:Device Types / IOMMU Device / Device operations / INVALIDATE request}
\item \ref{devicenormative:Device Types / IOMMU Device / Device operations / PROBE request}
\item \ref{devicenormative:Device Types / IOMMU Device / Device operations / PROBE properties / RESVMEM}
\item \ref{devicenormative:Device Types / IOMMU Device / Device operations / Fault reporting}
diff --git a/device-types/iommu/driver-conformance.tex b/device-types/iommu/driver-conformance.tex
index d7a313c..fa77bc7 100644
--- a/device-types/iommu/driver-conformance.tex
+++ b/device-types/iommu/driver-conformance.tex
@@ -12,6 +12,7 @@
\item \ref{drivernormative:Device Types / IOMMU Device / Device operations / DETACH request}
\item \ref{drivernormative:Device Types / IOMMU Device / Device operations / MAP request}
\item \ref{drivernormative:Device Types / IOMMU Device / Device operations / UNMAP request}
+\item \ref{drivernormative:Device Types / IOMMU Device / Device operations / INVALIDATE request}
\item \ref{drivernormative:Device Types / IOMMU Device / Device operations / PROBE request}
\item \ref{drivernormative:Device Types / IOMMU Device / Device operations / PROBE properties / RESVMEM}
\item \ref{drivernormative:Device Types / IOMMU Device / Device operations / Fault reporting}
--
2.43.0
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