From: Owen Smith <owen.smith@citrix.com>
Date: Thu, 16 Feb 2023 11:55:45 +0000 (+0000)
Subject: Skip uninitialized CPUs
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=b2473b5924773ce55624b2e0b8802d811ba77afb;p=pvdrivers%2Fwin%2Fxenbus.git

Skip uninitialized CPUs

EvtchnFifoAcquire() will loop through all CPUs to call EVTCHNOP_init_control.
Skip any CPUs that are not initialized, which is indicated by
SystemProcessorVcpuId() failing, instead of failing the Acquire operation.

This is primarily an issue when KeQueryMaximumProcessorCountEx() returns
a different value to KeQueryActiveProcessorCountEx(), or the system
processor callback has not been called with KeProcessorAddCompleteNotify
for that CPU.

Signed-off-by: Owen Smith <owen.smith@citrix.com>

Fix up error path that also calls SystemProcessorVcpuId().

Signed-off-by: Paul Durrant <pdurrant@amazon.com>
---

diff --git a/src/xenbus/evtchn_fifo.c b/src/xenbus/evtchn_fifo.c
index a8dab8c..88b810a 100644
--- a/src/xenbus/evtchn_fifo.c
+++ b/src/xenbus/evtchn_fifo.c
@@ -507,14 +507,20 @@ EvtchnFifoAcquire(
         PFN_NUMBER          Pfn;
         PHYSICAL_ADDRESS    Address;
 
+        status = SystemProcessorVcpuId(Index, &vcpu_id);
+
+        Index++;
+
+        if (status == STATUS_NOT_SUPPORTED)
+            continue;
+
+        if (!NT_SUCCESS(status))
+            goto fail1;
+
         Mdl = __AllocatePage();
 
         status = STATUS_NO_MEMORY;
         if (Mdl == NULL)
-            goto fail1;
-
-        status = SystemProcessorVcpuId(Index, &vcpu_id);
-        if (!NT_SUCCESS(status))
             goto fail2;
 
         Pfn = MmGetMdlPfnArray(Mdl)[0];
@@ -532,8 +538,6 @@ EvtchnFifoAcquire(
                   Address.LowPart);
 
         Context->ControlBlockMdl[vcpu_id] = Mdl;
-
-        Index++;
     }
 
     Trace("<====\n");
@@ -546,11 +550,11 @@ done:
 fail3:
     Error("fail3\n");
 
+    __FreePage(Mdl);
+
 fail2:
     Error("fail2\n");
 
-    __FreePage(Mdl);
-
 fail1:
     Error("fail1 (%08x)\n", status);
 
@@ -559,7 +563,11 @@ fail1:
     while (--Index >= 0) {
         unsigned int    vcpu_id;
 
-        (VOID) SystemProcessorVcpuId(Index, &vcpu_id);
+        status = SystemProcessorVcpuId(Index, &vcpu_id);
+        if (status == STATUS_NOT_SUPPORTED)
+            continue;
+
+        BUG_ON(!NT_SUCCESS(status));
 
         Mdl = Context->ControlBlockMdl[vcpu_id];
         Context->ControlBlockMdl[vcpu_id] = NULL;