Re: [PATCH] IntelSiliconPkg/VTdDxe: Change EBS Event TPL to CALLBACK.

["Zeng, Star" <star.zeng@intel.com>]

So there will be a guidance for this " PCI device disable BME at NOTIFY " to be documented?

Thanks,
Star
-----Original Message-----
From: Yao, Jiewen 
Sent: Thursday, October 26, 2017 2:03 PM
To: Zeng, Star <star.zeng@intel.com>; edk2-devel@lists.01.org
Cc: Laszlo Ersek (lersek@redhat.com) <lersek@redhat.com>
Subject: RE: [PATCH] IntelSiliconPkg/VTdDxe: Change EBS Event TPL to CALLBACK.

Right. In the future, we will let PCI device disable BME at NOTIFY.

So we let IOMMU use CALLBACK, to make sure BME is disabled before IOMMU is disabled.

Thank you
Yao Jiewen

> -----Original Message-----
> From: Zeng, Star
> Sent: Thursday, October 26, 2017 1:55 PM
> To: Yao, Jiewen <jiewen.yao@intel.com>; edk2-devel@lists.01.org
> Cc: Laszlo Ersek (lersek@redhat.com) <lersek@redhat.com>; Zeng, Star 
> <star.zeng@intel.com>
> Subject: RE: [PATCH] IntelSiliconPkg/VTdDxe: Change EBS Event TPL to CALLBACK.
> 
> I am confused.
> 
> Is this patch to make the device driver's EBS event notification to be 
> run before IntelVTdDxe's EBS event notification?
> 
> If yes, this patch seemingly can only make sure the behavior when the 
> device driver's EBS event notification is at NOTIFY, but not CALLBACK.
> 
> 
> Thanks,
> Star
> -----Original Message-----
> From: Yao, Jiewen
> Sent: Thursday, October 26, 2017 1:16 PM
> To: Zeng, Star <star.zeng@intel.com>; edk2-devel@lists.01.org
> Cc: Laszlo Ersek (lersek@redhat.com) <lersek@redhat.com>
> Subject: RE: [PATCH] IntelSiliconPkg/VTdDxe: Change EBS Event TPL to CALLBACK.
> 
> That is fine.
> 
> Here, disabling IOMMU means to disable the protection and allow all 
> DMA access.
> I do not think it will bring any functional impact.
> 
> Thank you
> Yao Jiewen
> 
> 
> > -----Original Message-----
> > From: Zeng, Star
> > Sent: Thursday, October 26, 2017 12:58 PM
> > To: Yao, Jiewen <jiewen.yao@intel.com>; edk2-devel@lists.01.org
> > Cc: Laszlo Ersek (lersek@redhat.com) <lersek@redhat.com>; Zeng, Star 
> > <star.zeng@intel.com>
> > Subject: RE: [PATCH] IntelSiliconPkg/VTdDxe: Change EBS Event TPL to
> CALLBACK.
> >
> > Some device driver may also have exit boot service event at 
> > CALLBACK, for example AtaPassThruExitBootServices() that was added by Laszlo.
> >
> >
> > Thanks,
> > Star
> > -----Original Message-----
> > From: Yao, Jiewen
> > Sent: Thursday, October 26, 2017 10:14 AM
> > To: edk2-devel@lists.01.org
> > Cc: Zeng, Star <star.zeng@intel.com>
> > Subject: [PATCH] IntelSiliconPkg/VTdDxe: Change EBS Event TPL to CALLBACK.
> >
> > Change ExitBootServices TPL to CALLBACK, so that a device can 
> > disable BME before IOMMU grants access right.
> >
> > Cc: Star Zeng <star.zeng@intel.com>
> > Contributed-under: TianoCore Contribution Agreement 1.1
> > Signed-off-by: Jiewen Yao <jiewen.yao@intel.com>
> > ---
> >  IntelSiliconPkg/Feature/VTd/IntelVTdDxe/DmaProtection.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/IntelSiliconPkg/Feature/VTd/IntelVTdDxe/DmaProtection.c
> > b/IntelSiliconPkg/Feature/VTd/IntelVTdDxe/DmaProtection.c
> > index f5de01f..4a4d82e 100644
> > --- a/IntelSiliconPkg/Feature/VTd/IntelVTdDxe/DmaProtection.c
> > +++ b/IntelSiliconPkg/Feature/VTd/IntelVTdDxe/DmaProtection.c
> > @@ -483,7 +483,7 @@ InitializeDmaProtection (
> >
> >    Status = gBS->CreateEventEx (
> >                    EVT_NOTIFY_SIGNAL,
> > -                  TPL_NOTIFY,
> > +                  TPL_CALLBACK,
> >                    OnExitBootServices,
> >                    NULL,
> >                    &gEfiEventExitBootServicesGuid, @@ -492,7 +492,7 
> > @@ InitializeDmaProtection (
> >    ASSERT_EFI_ERROR (Status);
> >
> >    Status = EfiCreateEventLegacyBootEx (
> > -             TPL_NOTIFY,
> > +             TPL_CALLBACK,
> >               OnLegacyBoot,
> >               NULL,
> >               &LegacyBootEvent
> > --
> > 2.7.4.windows.1