Re: [PATCH 3/6] Delete stornvme's StartOverride

[Paul Durrant <xadimgnik@xxxxxxxxx>]

On 17/06/2021 13:33, Owen Smith wrote:
> Using an emulated NVMe device for installation will not be able to
> revert to emulated NVMe device once xenvbd has been used to boot. This
> is due to stornvme creating a StartOverride value that overrides
> stornvme's StartType to manual (from boot) when stornvme is not loaded
> during boot. This occurs when xenbus has unplugged the emulated NVMe
> controller at boot. Disabling the unplug is not sufficient to have
> stornvme load at boot, which results in a 0x7B bugcheck.
Ick!

> Signed-off-by: Owen Smith <owen.smith@xxxxxxxxxx>
> ---
>   src/monitor/monitor.c | 60 +++++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 60 insertions(+)
>
> diff --git a/src/monitor/monitor.c b/src/monitor/monitor.c
Not sure the monitor is the best place to do this; it seems a little too 
critical for that. Could we use this ancient interface instead?
https://docs.microsoft.com/en-us/windows-hardware/drivers/ddi/ntddk/nf-ntddk-ioregisterbootdriverreinitialization

  Paul

> index 9adfb79..c858249 100644
> --- a/src/monitor/monitor.c
> +++ b/src/monitor/monitor.c
> @@ -1172,6 +1172,64 @@ fail1:
>       return FALSE;
>   }
>   
> +static BOOL
> +DeleteStartOverride(
> +    _In_    LPTSTR      DriverName
> +    )
> +{
> +    TCHAR               ServiceKeyName[MAX_PATH];
> +    HKEY                Key;
> +    HRESULT             Error;
> +
> +    Error = StringCbPrintf(ServiceKeyName,
> +                            MAX_PATH,
> +                            SERVICES_KEY "\\%s",
> +                            DriverName);
> +    if (!SUCCEEDED(Error))
> +        goto fail1;
> +
> +    Error = RegOpenKeyEx(HKEY_LOCAL_MACHINE,
> +                         ServiceKeyName,
> +                         0,
> +                         KEY_ALL_ACCESS,
> +                         &Key);
> +    if (Error != ERROR_SUCCESS) {
> +        SetLastError(Error);
> +        goto fail2;
> +    }
> +
> +    Error = RegDeleteTree(Key,
> +                          "StartOverride");
> +    if (Error != ERROR_SUCCESS) {
> +        SetLastError(Error);
> +        goto fail3;
> +    }
> +
> +    RegCloseKey(Key);
> +
> +    return TRUE;
> +
> +fail3:
> +    Log("fail3");
> +
> +    RegCloseKey(Key);
> +
> +fail2:
> +    Log("fail2");
> +
> +fail1:
> +    Error = GetLastError();
> +
> +    {
> +        PTCHAR  Message;
> +        Message = GetErrorMessage(Error);
> +        Log("fail1 (%s)", Message);
> +        LocalFree(Message);
> +    }
> +
> +    return FALSE;
> +}
> +
>   VOID WINAPI
>   MonitorMain(
>       _In_    DWORD       argc,
> @@ -1251,6 +1309,7 @@ MonitorMain(
>       if (!Success)
>           goto fail9;
>   
> +    (VOID) DeleteStartOverride("stornvme");
>       SetEvent(Context->RequestEvent);
>   
>       ReportStatus(SERVICE_RUNNING, NO_ERROR, 0);
> @@ -1285,6 +1344,7 @@ MonitorMain(
>       }
>   
>   done:
> +    (VOID) DeleteStartOverride("stornvme");
>       (VOID) RegDeleteTree(Context->RequestKey, NULL);
>   
>       free(Context->Question);