Re: [XENVKBD PATCH] Fix FDO invalidation when no devices are present

[Owen Smith <owen.smith@xxxxxxxxx>]

Reviewed-by: Owen Smith <owen.smith@xxxxxxxxx>

On Wed, Jul 23, 2025 at 3:05 PM Tu Dinh <ngoc-tu.dinh@xxxxxxxxxx> wrote:

__FdoEnumerate is called with Devices==NULL to signify that the entire
device xenstore key has been removed. However, the PdoIsMissing check
was under the Devices!=NULL check, and will never be called. This means
existing PDOs will never be validated in this situation.

Instead, always check for the PDO's existence even if Devices==NULL.

Fixes: 270cb87d3d2a ("Invalidate FDOs when no devices are present")
Signed-off-by: Tu Dinh <ngoc-tu.dinh@xxxxxxxxxx>
---
This is rather untested, but the logic was rewritten to follow xenvif.
---
 src/xenvkbd/fdo.c | 32 ++++++++++++++++----------------
 1 file changed, 16 insertions(+), 16 deletions(-)

diff --git a/src/xenvkbd/fdo.c b/src/xenvkbd/fdo.c
index 98297fc..12b8717 100644
--- a/src/xenvkbd/fdo.c
+++ b/src/xenvkbd/fdo.c
@@ -771,23 +771,23 @@ __FdoEnumerate(
                         break;
                     }
                 }
+            }

-                if (!PdoIsMissing(Pdo)) {
-                    if (PdoIsEjectRequested(Pdo)) {
-                        IoRequestDeviceEject(PdoGetDeviceObject(Pdo));
-                    } else if (Missing) {
-                        PdoSetMissing(Pdo, "device disappeared");
-
-                        // If the PDO has not yet been enumerated then we can
-                        // go ahead and mark it as deleted, otherwise we need
-                        // to notify PnP manager and wait for the REMOVE_DEVICE
-                        // IRP.
-                        if (PdoGetDevicePnpState(Pdo) == Present) {
-                            PdoSetDevicePnpState(Pdo, Deleted);
-                            PdoDestroy(Pdo);
-                        } else {
-                            NeedInvalidate = TRUE;
-                        }
+            if (!PdoIsMissing(Pdo)) {
+                if (PdoIsEjectRequested(Pdo)) {
+                    IoRequestDeviceEject(PdoGetDeviceObject(Pdo));
+                } else if (Missing) {
+                    PdoSetMissing(Pdo, "device disappeared");
+
+                    // If the PDO has not yet been enumerated then we can
+                    // go ahead and mark it as deleted, otherwise we need
+                    // to notify PnP manager and wait for the REMOVE_DEVICE
+                    // IRP.
+                    if (PdoGetDevicePnpState(Pdo) == Present) {
+                        PdoSetDevicePnpState(Pdo, Deleted);
+                        PdoDestroy(Pdo);
+                    } else {
+                        NeedInvalidate = TRUE;
                     }
                 }
             }
--
2.50.0.windows.2


Ngoc Tu Dinh | Vates XCP-ng Developer

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