Re: [win-pv-devel] [PATCH 1/2] Continue checking for emulated type if not PCI or IDE

["Durrant, Paul" <pdurrant@xxxxxxxxxxxx>]

> -----Original Message-----
> From: win-pv-devel <win-pv-devel-bounces@xxxxxxxxxxxxxxxxxxxx> On Behalf
> Of Owen Smith
> Sent: 05 February 2020 16:53
> To: win-pv-devel@xxxxxxxxxxxxxxxxxxxx
> Cc: Owen Smith <owen.smith@xxxxxxxxxx>
> Subject: [win-pv-devel] [PATCH 1/2] Continue checking for emulated type if
> not PCI or IDE
> 
> When determining the XENFILT_EMULATED_OBJECT_TYPE, keep trying all
> supplied HardwareIDs/CompatibleIDs until an exact match is made. If an
> early match is made that is not a valid type, ignore the match and
> continue checking for either "PCI" or "IDE".
> This covers situations where XenFilt's Parameters key contains stale
> strings from previous (v8.x) versions, and fixes an upgrade failure when
> upgrading v8.x to v9.x
> 
> Signed-off-by: Owen Smith <owen.smith@xxxxxxxxxx>
> ---
>  src/xenfilt/driver.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/src/xenfilt/driver.c b/src/xenfilt/driver.c
> index 0167c21..53df169 100644
> --- a/src/xenfilt/driver.c
> +++ b/src/xenfilt/driver.c
> @@ -760,7 +760,8 @@ DriverGetEmulatedType(
>                  Type = XENFILT_EMULATED_OBJECT_TYPE_IDE;
> 
>              RegistryFreeSzValue(Ansi);
> -            break;
> +            if (Type != XENFILT_EMULATED_OBJECT_TYPE_UNKNOWN)
> +                break;
>          } else {
>              Trace("NO MATCH: %s\n", &Id[Index]);
>          }
> --

I think it would be neater to code it as follows:

diff --git a/src/xenfilt/driver.c b/src/xenfilt/driver.c
index 0167c21..8f14ec8 100644
--- a/src/xenfilt/driver.c
+++ b/src/xenfilt/driver.c
@@ -738,7 +738,7 @@ DriverGetEmulatedType(
     Type = XENFILT_EMULATED_OBJECT_TYPE_UNKNOWN;
     Index = 0;

-    for (;;) {
+    do {
         ULONG           Length;
         PANSI_STRING    Ansi;
         NTSTATUS        status;
@@ -760,13 +760,12 @@ DriverGetEmulatedType(
                 Type = XENFILT_EMULATED_OBJECT_TYPE_IDE;

             RegistryFreeSzValue(Ansi);
-            break;
         } else {
             Trace("NO MATCH: %s\n", &Id[Index]);
         }

         Index += Length + 1;
-    }
+    } while (Type == XENFILT_EMULATED_OBJECT_TYPE_UNKNOWN);

     return Type;
 }

  Paul
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