Changeset 94969 in vbox for trunk/src/VBox/Devices/VirtIO/VirtioCore.h

Timestamp:

May 9, 2022 5:06:17 PM (3 years ago)

Author:

vboxsync

Message:

Devices/Virtio|ai: Fixes and performance improvements for the 1.0 virtio-net implementation, bugref:8651

File:

• trunk/src/VBox/Devices/VirtIO/VirtioCore.h (modified) (4 diffs)

trunk/src/VBox/Devices/VirtIO/VirtioCore.h

@@ -22 +22 @@
 # pragma once
 #endif
+
+/* Do not allocate VIRTQBUF from the heap when possible */
+#define VIRTIO_VBUF_ON_STACK 1
 
 #include <iprt/ctype.h>
@@ -676 +679 @@
 uint16_t virtioCoreVirtqAvailBufCount(PPDMDEVINS pDevIns, PVIRTIOCORE pVirtio, uint16_t uVirtqNbr);
 
+#ifdef VIRTIO_VBUF_ON_STACK
+/**
+ * This function is identical to virtioCoreR3VirtqAvailBufGet(), *except* it doesn't consume
+ * peeked buffer from avail ring of the virtq. The function *becomes* identical to the
+ * virtioCoreR3VirtqAvailBufGet() only if virtioCoreR3VirtqAvailRingNext() is invoked to
+ * consume buf from the queue's avail ring, followed by invocation of virtioCoreR3VirtqUsedBufPut(),
+ * to hand host-processed buffer back to guest, which completes guest-initiated virtq buffer circuit.
+ *
+ * @param   pDevIns     The device instance.
+ * @param   pVirtio     Pointer to the shared virtio state.
+ * @param   uVirtqNbr   Virtq number
+ * @param   pVirtqBuf   Pointer to descriptor chain that contains the
+ *                      pre-processed transaction information pulled from the virtq.
+ *
+ * @returns VBox status code:
+ * @retval  VINF_SUCCESS         Success
+ * @retval  VERR_INVALID_STATE   VirtIO not in ready state (asserted).
+ * @retval  VERR_NOT_AVAILABLE   If the queue is empty.
+ */
+int  virtioCoreR3VirtqAvailBufPeek(PPDMDEVINS pDevIns, PVIRTIOCORE pVirtio, uint16_t uVirtqNbr,
+                                   PVIRTQBUF pVirtqBuf);
+
+/**
+ * This function fetches the next buffer (descriptor chain) from the VirtIO "avail" ring of
+ * indicated queue, separating the buf's s/g vectors into OUT (e.g. guest-to-host)
+ * components and and IN (host-to-guest) components.
+ *
+ * Caller is responsible for GCPhys to host virtual memory conversions. If the
+ * virtq buffer being peeked at is "consumed", virtioCoreR3VirtqAvailRingNext() must
+ * be called, and after that virtioCoreR3VirtqUsedBufPut() must be called to
+ * complete the buffer transfer cycle with the guest.
+ *
+ * @param   pDevIns     The device instance.
+ * @param   pVirtio     Pointer to the shared virtio state.
+ * @param   uVirtqNbr   Virtq number
+ * @param   pVirtqBuf   Pointer to descriptor chain that contains the
+ *                      pre-processed transaction information pulled from the virtq.
+ * @param   fRemove     flags whether to remove desc chain from queue (false = peek)
+ *
+ * @returns VBox status code:
+ * @retval  VINF_SUCCESS         Success
+ * @retval  VERR_INVALID_STATE   VirtIO not in ready state (asserted).
+ * @retval  VERR_NOT_AVAILABLE   If the queue is empty.
+ */
+int  virtioCoreR3VirtqAvailBufGet(PPDMDEVINS pDevIns, PVIRTIOCORE pVirtio, uint16_t uVirtqNbr,
+                                  PVIRTQBUF pVirtqBuf, bool fRemove);
+
+/**
+ * Fetches a specific descriptor chain using avail ring of indicated queue and converts the
+ * descriptor chain into its OUT (to device) and IN (to guest) components.
+ *
+ * The caller is responsible for GCPhys to host virtual memory conversions and *must*
+ * return the virtq buffer using virtioCoreR3VirtqUsedBufPut() to complete the roundtrip
+ * virtq transaction.
+ * *
+ * @param   pDevIns     The device instance.
+ * @param   pVirtio     Pointer to the shared virtio state.
+ * @param   uVirtqNbr   Virtq number
+ * @param   pVirtqBuf   Pointer to descriptor chain that contains the
+ *                      pre-processed transaction information pulled from the virtq.
+ * @param   fRemove     flags whether to remove desc chain from queue (false = peek)
+ *
+ * @returns VBox status code:
+ * @retval  VINF_SUCCESS         Success
+ * @retval  VERR_INVALID_STATE   VirtIO not in ready state (asserted).
+ * @retval  VERR_NOT_AVAILABLE   If the queue is empty.
+ */
+int virtioCoreR3VirtqAvailBufGet(PPDMDEVINS pDevIns, PVIRTIOCORE pVirtio, uint16_t uVirtqNbr,
+                                  uint16_t uHeadIdx, PVIRTQBUF pVirtqBuf);
+#else /* !VIRTIO_VBUF_ON_STACK */
 /**
  * This function is identical to virtioCoreR3VirtqAvailBufGet(), *except* it doesn't consume
@@ -748 +821 @@
 int virtioCoreR3VirtqAvailBufGet(PPDMDEVINS pDevIns, PVIRTIOCORE pVirtio, uint16_t uVirtqNbr,
                                   uint16_t uHeadIdx, PPVIRTQBUF ppVirtqBuf);
+#endif /* !VIRTIO_VBUF_ON_STACK */
 
 /**
@@ -1092 +1166 @@
 int  virtioCoreVirtqUsedRingSync(PPDMDEVINS pDevIns, PVIRTIOCORE pVirtio, uint16_t uVirtqNbr);
 
+#ifdef VIRTIO_VBUF_ON_STACK
+/**
+ * Allocates a descriptor chain object with the reference count of one. Copying the reference
+ * to this object requires a call to virtioCoreR3VirtqBufRetain. All references must be later
+ * released with virtioCoreR3VirtqBufRelease. Just to be clear, one alloc plus one retain will
+ * require two releases.
+ *
+ * @returns A descriptor chain object.
+ *
+ * @retval  NULL if out of memory.
+ * 
+ * NOTE: VIRTQBUF_T objects allocated on the stack will have garbage in the u32Magic field,
+ * triggering an assertion if virtioCoreR3VirtqBufRelease is called on them.
+ */
+PVIRTQBUF virtioCoreR3VirtqBufAlloc(void);
+#endif /* VIRTIO_VBUF_ON_STACK */
+
 /**
  * Retains a reference to the given descriptor chain.