Re: [win-pv-devel] [PATCH] Add registry overrides for features (v2)

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: win-pv-devel [mailto:win-pv-devel-bounces@xxxxxxxxxxxxxxxxxxxx] On
> Behalf Of Paul Durrant
> Sent: 03 February 2017 12:42
> To: Owen Smith <owen.smith@xxxxxxxxxx>; win-pv-
> devel@xxxxxxxxxxxxxxxxxxxx
> Cc: Owen Smith <owen.smith@xxxxxxxxxx>
> Subject: Re: [win-pv-devel] [PATCH] Add registry overrides for features (v2)
> 
> > -----Original Message-----
> > From: win-pv-devel [mailto:win-pv-devel-bounces@xxxxxxxxxxxxxxxxxxxx]
> On
> > Behalf Of owen.smith@xxxxxxxxxx
> > Sent: 03 February 2017 12:39
> > To: win-pv-devel@xxxxxxxxxxxxxxxxxxxx
> > Cc: Owen Smith <owen.smith@xxxxxxxxxx>
> > Subject: [win-pv-devel] [PATCH] Add registry overrides for features (v2)
> >
> > From: Owen Smith <owen.smith@xxxxxxxxxx>
> >
> > * Add a REG_DWORD to XenVbd's Parameters key, with names based
> >   on the features, as per xenstore value, and set to 0 to
> >   override use of that feature.
> >
> > Changes over v1:
> > * removed check on DriverGerParametersKey() return value, as its
> >   guaranteed to be valid (failure to get the key results in
> >   DriverEntry failing)
> >
> > For example,
> >  "HKLM\System\CCS\Services\XenVbd\Parameters" "feature-barrier" 0
> >   will prevent the frontend issuing BLKIF_OP_WRITE_BARRIERs
> >  "HKLM\System\CCS\Services\XenVbd\Parameters" "feature-discard" 0
> >   will prevent the frontend issuing BLKIF_OP_DISCARDs
> >
> > Signed-off-by: Owen Smith <owen.smith@xxxxxxxxxx>
> 
> LGTM.
> 
> Acked-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
> 

Now that it has built I'm also going to cherry-pick this back onto staging-8.2 
as it should be very useful.

  Paul

> > ---
> >  src/xenvbd/driver.c   | 16 ++++++++++++++++
> >  src/xenvbd/driver.h   |  5 +++++
> >  src/xenvbd/frontend.c | 29 +++++++++++++++++++++++++++++
> >  3 files changed, 50 insertions(+)
> >
> > diff --git a/src/xenvbd/driver.c b/src/xenvbd/driver.c
> > index 114c740..1f713c4 100644
> > --- a/src/xenvbd/driver.c
> > +++ b/src/xenvbd/driver.c
> > @@ -82,6 +82,22 @@ __DriverParseOption(
> >      RegistryFreeSzValue(Option);
> >  }
> >
> > +static FORCEINLINE HANDLE
> > +__DriverGetParametersKey(
> > +    VOID
> > +    )
> > +{
> > +    return Driver.ParametersKey;
> > +}
> > +
> > +HANDLE
> > +DriverGetParametersKey(
> > +    VOID
> > +    )
> > +{
> > +    return __DriverGetParametersKey();
> > +}
> > +
> >  NTSTATUS
> >  DriverDispatchPnp(
> >      IN  PDEVICE_OBJECT  DeviceObject,
> > diff --git a/src/xenvbd/driver.h b/src/xenvbd/driver.h
> > index cf55330..e7730a9 100644
> > --- a/src/xenvbd/driver.h
> > +++ b/src/xenvbd/driver.h
> > @@ -57,6 +57,11 @@ typedef struct _XENVBD_PARAMETERS {
> >
> >  extern XENVBD_PARAMETERS    DriverParameters;
> >
> > +extern HANDLE
> > +DriverGetParametersKey(
> > +    VOID
> > +    );
> > +
> >  extern NTSTATUS
> >  DriverDispatchPnp(
> >      IN  PDEVICE_OBJECT  DeviceObject,
> > diff --git a/src/xenvbd/frontend.c b/src/xenvbd/frontend.c
> > index 11e9121..e65a3b0 100644
> > --- a/src/xenvbd/frontend.c
> > +++ b/src/xenvbd/frontend.c
> > @@ -30,6 +30,7 @@
> >   */
> >
> >  #include "frontend.h"
> > +#include "registry.h"
> >  #include "driver.h"
> >  #include "fdo.h"
> >  #include "pdoinquiry.h"
> > @@ -621,6 +622,7 @@ FrontendReadFeature(
> >  {
> >      NTSTATUS        status;
> >      PCHAR           Buffer;
> > +    ULONG           Override;
> >      BOOLEAN         Old = *Value;
> >
> >      status = XENBUS_STORE(Read,
> > @@ -637,6 +639,15 @@ FrontendReadFeature(
> >                      Frontend->Store,
> >                      Buffer);
> >
> > +    // check registry for disable-override
> > +    status = RegistryQueryDwordValue(DriverGetParametersKey(),
> > +                                    Name,
> > +                                    &Override);
> > +    if (NT_SUCCESS(status)) {
> > +        if (Override == 0)
> > +            *Value = FALSE;
> > +    }
> > +
> >      return Old != *Value;
> >  }
> >
> > @@ -644,11 +655,13 @@ static FORCEINLINE BOOLEAN
> >  FrontendReadValue32(
> >      IN  PXENVBD_FRONTEND            Frontend,
> >      IN  PCHAR                       Name,
> > +    IN  BOOLEAN                     AllowOverride,
> >      IN  PULONG                      Value
> >      )
> >  {
> >      NTSTATUS        status;
> >      PCHAR           Buffer;
> > +    ULONG           Override;
> >      ULONG           Old = *Value;
> >
> >      status = XENBUS_STORE(Read,
> > @@ -665,6 +678,16 @@ FrontendReadValue32(
> >                      Frontend->Store,
> >                      Buffer);
> >
> > +    // check registry for disable-override
> > +    if (AllowOverride) {
> > +        status = RegistryQueryDwordValue(DriverGetParametersKey(),
> > +                                        Name,
> > +                                        &Override);
> > +        if (NT_SUCCESS(status)) {
> > +            *Value = Override;
> > +        }
> > +    }
> > +
> >      return Old != *Value;
> >  }
> >
> > @@ -727,12 +750,15 @@ __ReadDiskInfo(
> >
> >      Changed |= FrontendReadValue32(Frontend,
> >                                    "info",
> > +                                  FALSE,
> >                                    &Frontend->DiskInfo.DiskInfo);
> >      Changed |= FrontendReadValue32(Frontend,
> >                                    "sector-size",
> > +                                  FALSE,
> >                                    &Frontend->DiskInfo.SectorSize);
> >      Changed |= FrontendReadValue32(Frontend,
> >                                    "physical-sector-size",
> > +                                  FALSE,
> >                                    &Frontend->DiskInfo.PhysSectorSize);
> >      Changed |= FrontendReadValue64(Frontend,
> >                                    "sectors",
> > @@ -780,6 +806,7 @@ FrontendReadFeatures(
> >                                     &Frontend->Caps.Removable);
> >      Changed |= FrontendReadValue32(Frontend,
> >                                     "feature-max-indirect-segments",
> > +                                   TRUE,
> >                                     &Frontend->Features.Indirect);
> >      Changed |= FrontendReadFeature(Frontend,
> >                                     "feature-persistent",
> > @@ -821,9 +848,11 @@ FrontendReadDiskInfo(
> >                                     &Frontend->DiskInfo.DiscardSecure);
> >      Changed |= FrontendReadValue32(Frontend,
> >                                     "discard-alignment",
> > +                                   TRUE,
> >                                     &Frontend->DiskInfo.DiscardAlignment);
> >      Changed |= FrontendReadValue32(Frontend,
> >                                     "discard-granularity",
> > +                                   TRUE,
> >                                     &Frontend->DiskInfo.DiscardGranularity);
> >
> >      if (!Changed)
> > --
> > 2.8.3
> >
> >
> > _______________________________________________
> > win-pv-devel mailing list
> > win-pv-devel@xxxxxxxxxxxxxxxxxxxx
> > https://lists.xenproject.org/cgi-bin/mailman/listinfo/win-pv-devel
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