Changeset 82978 in vbox for trunk

Timestamp:

Feb 4, 2020 2:52:50 PM (5 years ago)

Author:

vboxsync

svn:sync-xref-src-repo-rev:

135987

Message:

VMM/GMMR0: Introduce a spinlock to protect the AVL tree and associated TLB. bugref:9627

File:

• trunk/src/VBox/VMM/VMMR0/GMMR0.cpp (modified) (14 diffs)

trunk/src/VBox/VMM/VMMR0/GMMR0.cpp

@@ -177 +177 @@
 #include <iprt/mp.h>
 #include <iprt/semaphore.h>
+#include <iprt/spinlock.h>
 #include <iprt/string.h>
 #include <iprt/time.h>
@@ -522 +523 @@
     RTNATIVETHREAD      hMtxOwner;
 #endif
-    /** The chunk tree. */
+    /** Spinlock protecting the AVL tree.
+     * @todo Make this a read-write spinlock as we should allow concurrent
+     *       lookups. */
+    RTSPINLOCK          hSpinLockTree;
+    /** The chunk tree.
+     * Protected by hSpinLockTree. */
     PAVLU32NODECORE     pChunks;
-    /** The chunk TLB. */
+    /** The chunk TLB.
+     * Protected by hSpinLockTree. */
     GMMCHUNKTLB         ChunkTLB;
     /** The private free set. */
@@ -810 +817 @@
                 break;
         }
+        pGMM->hSpinLockTree = NIL_RTSPINLOCK;
+        if (RT_SUCCESS(rc))
+            rc = RTSpinlockCreate(&pGMM->hSpinLockTree, RTSPINLOCK_FLAGS_INTERRUPT_SAFE, "gmm-chunk-tree");
         if (RT_SUCCESS(rc))
         {
@@ -884 +894 @@
          * Bail out.
          */
+        RTSpinlockDestroy(pGMM->hSpinLockTree);
         while (iMtx-- > 0)
             RTSemFastMutexDestroy(pGMM->aChunkMtx[iMtx].hMtx);
@@ -931 +942 @@
     pGMM->hMtx        = NIL_RTSEMFASTMUTEX;
 #endif
+    RTSpinlockDestroy(pGMM->hSpinLockTree);
+    pGMM->hSpinLockTree = NIL_RTSPINLOCK;
 
     /* Free any chunks still hanging around. */
@@ -1845 +1858 @@
  * @param   idChunk     The ID of the chunk to find.
  * @param   pTlbe       Pointer to the TLB entry.
+ *
+ * @note    Caller owns spinlock.
  */
 static PGMMCHUNK gmmR0GetChunkSlow(PGMM pGMM, uint32_t idChunk, PGMMCHUNKTLBE pTlbe)
@@ -1857 +1872 @@
 
 /**
- * Finds a allocation chunk.
+ * Finds a allocation chunk, spin-locked.
  *
  * This is not expected to fail and will bitch if it does.
@@ -1865 +1880 @@
  * @param   idChunk     The ID of the chunk to find.
  */
+DECLINLINE(PGMMCHUNK) gmmR0GetChunkLocked(PGMM pGMM, uint32_t idChunk)
+{
+    /*
+     * Do a TLB lookup, branch if not in the TLB.
+     */
+    PGMMCHUNKTLBE pTlbe  = &pGMM->ChunkTLB.aEntries[GMM_CHUNKTLB_IDX(idChunk)];
+    PGMMCHUNK     pChunk = pTlbe->pChunk;
+    if (   pChunk == NULL
+        || pTlbe->idChunk != idChunk)
+        pChunk = gmmR0GetChunkSlow(pGMM, idChunk, pTlbe);
+    return pChunk;
+}
+
+
+/**
+ * Finds a allocation chunk.
+ *
+ * This is not expected to fail and will bitch if it does.
+ *
+ * @returns Pointer to the allocation chunk, NULL if not found.
+ * @param   pGMM        Pointer to the GMM instance.
+ * @param   idChunk     The ID of the chunk to find.
+ */
 DECLINLINE(PGMMCHUNK) gmmR0GetChunk(PGMM pGMM, uint32_t idChunk)
 {
-    /*
-     * Do a TLB lookup, branch if not in the TLB.
-     */
-    PGMMCHUNKTLBE pTlbe = &pGMM->ChunkTLB.aEntries[GMM_CHUNKTLB_IDX(idChunk)];
-    if (    pTlbe->idChunk != idChunk
-        ||  !pTlbe->pChunk)
-        return gmmR0GetChunkSlow(pGMM, idChunk, pTlbe);
-    return pTlbe->pChunk;
+    RTSpinlockAcquire(pGMM->hSpinLockTree);
+    PGMMCHUNK pChunk = gmmR0GetChunkLocked(pGMM, idChunk);
+    RTSpinlockRelease(pGMM->hSpinLockTree);
+    return pChunk;
 }
 
@@ -2239 +2273 @@
             {
                 pChunk->Core.Key = gmmR0AllocateChunkId(pGMM);
-                if (    pChunk->Core.Key != NIL_GMM_CHUNKID
-                    &&  pChunk->Core.Key <= GMM_CHUNKID_LAST
-                    &&  RTAvlU32Insert(&pGMM->pChunks, &pChunk->Core))
+                if (   pChunk->Core.Key != NIL_GMM_CHUNKID
+                    && pChunk->Core.Key <= GMM_CHUNKID_LAST)
                 {
-                    pGMM->cChunks++;
-                    RTListAppend(&pGMM->ChunkList, &pChunk->ListNode);
-                    gmmR0LinkChunk(pChunk, pSet);
-                    LogFlow(("gmmR0RegisterChunk: pChunk=%p id=%#x cChunks=%d\n", pChunk, pChunk->Core.Key, pGMM->cChunks));
-
-                    if (ppChunk)
-                        *ppChunk = pChunk;
-                    GMM_CHECK_SANITY_UPON_LEAVING(pGMM);
-                    return VINF_SUCCESS;
+                    RTSpinlockAcquire(pGMM->hSpinLockTree);
+                    if (RTAvlU32Insert(&pGMM->pChunks, &pChunk->Core))
+                    {
+                        pGMM->cChunks++;
+                        RTListAppend(&pGMM->ChunkList, &pChunk->ListNode);
+                        RTSpinlockRelease(pGMM->hSpinLockTree);
+
+                        gmmR0LinkChunk(pChunk, pSet);
+
+                        LogFlow(("gmmR0RegisterChunk: pChunk=%p id=%#x cChunks=%d\n", pChunk, pChunk->Core.Key, pGMM->cChunks));
+
+                        if (ppChunk)
+                            *ppChunk = pChunk;
+                        GMM_CHECK_SANITY_UPON_LEAVING(pGMM);
+                        return VINF_SUCCESS;
+                    }
+                    RTSpinlockRelease(pGMM->hSpinLockTree);
                 }
 
@@ -3358 +3399 @@
     gmmR0UnlinkChunk(pChunk);
 
+    RTSpinlockAcquire(pGMM->hSpinLockTree);
+
     RTListNodeRemove(&pChunk->ListNode);
 
@@ -3372 +3415 @@
     Assert(pGMM->cChunks > 0);
     pGMM->cChunks--;
+
+    RTSpinlockRelease(pGMM->hSpinLockTree);
 
     /*
@@ -4398 +4443 @@
  * Gets the ring-0 virtual address for the given page.
  *
+ * This is used by PGM when IEM and such wants to access guest RAM from ring-0.
+ * One of the ASSUMPTIONS here is that the @a idPage is used by the VM and the
+ * corresponding chunk will remain valid beyond the call (at least till the EMT
+ * returns to ring-3).
+ *
  * @returns VBox status code.
  * @param   pGVM        Pointer to the kernel-only VM instace data.
@@ -4409 +4459 @@
     PGMM pGMM;
     GMM_GET_VALID_INSTANCE(pGMM, VERR_GMM_INSTANCE);
-    gmmR0MutexAcquire(pGMM); /** @todo shared access */
+
+    RTSpinlockAcquire(pGMM->hSpinLockTree);
 
     int rc;
-    PGMMCHUNK pChunk = gmmR0GetChunk(pGMM, idPage >> GMM_CHUNKID_SHIFT);
-    if (pChunk)
+    PGMMCHUNK pChunk = gmmR0GetChunkLocked(pGMM, idPage >> GMM_CHUNKID_SHIFT);
+    if (RT_LIKELY(pChunk))
     {
         const GMMPAGE *pPage = &pChunk->aPages[idPage & GMM_PAGEID_IDX_MASK];
@@ -4430 +4481 @@
         rc = VERR_GMM_PAGE_NOT_FOUND;
 
-    gmmR0MutexRelease(pGMM);
+    RTSpinlockRelease(pGMM->hSpinLockTree);
     return rc;
 }