[edk2-devel] [PATCH] MdeModulePkg/XhciDxe: Fix Aligned Page Allocation

Tue Oct 15 17:19:32 UTC 2019

Hello Hao,

Thanks for the clarification. I have made the changes and submitted a new patch. Also, in case the IOMMU PPI does not exist, we are now allocating the memory and adjust return pointers to be aligned. There is no freeing of unaligned pages here as PEI framework does not provide a mechanism for that.

Thanks
Ashish
________________________________
From: Wu, Hao A <hao.a.wu at intel.com>
Sent: Monday, October 14, 2019 7:21 PM
To: Ashish Singhal <ashishsingha at nvidia.com>; devel at edk2.groups.io <devel at edk2.groups.io>; Ni, Ray <ray.ni at intel.com>
Subject: RE: [edk2-devel] [PATCH] MdeModulePkg/XhciDxe: Fix Aligned Page Allocation

Hello,

Sorry for the delayed response.

For the PEI changes, I found that when using the function IoMmuFreeBuffer() to

free the first/last unaligned page(s), the below operations related to 'Mapping':

>|  Status = mIoMmu->SetAttribute (mIoMmu, Mapping, 0);

>|  Status = mIoMmu->Unmap (mIoMmu, Mapping);

will be done multiple times. I think they should only be done once and should

happen when freeing the aligned buffer.

Hence, I would suggest to add a new helper function called

IoMmuAllocateAlignedBuffer(), which will be similar to the existing

IoMmuAllocateBuffer() but with a couple of additional things to handle:

1. If the IOMMU PPI exists:

a. Allocate the buffer according to the real number of pages needed;

b. (New) Free the first & last unaligned pages;

c. Map the allocated aligned buffer;

d. Set the IOMMU attribute for the buffer.

2. If the IOMMU PPI does not exist:

a. Allocate the buffer according to the real number of pages needed;

b. (New) Free the first & last unaligned pages.

Also, could you help to separate the change for XhciPei into a separate patch?

It will be helpful to locate the exact commit made to XhciPei and XhciDxe in

the future.

Best Regards,

Hao Wu

From: Ashish Singhal [mailto:ashishsingha at nvidia.com]
Sent: Tuesday, October 15, 2019 2:17 AM
To: Wu, Hao A; devel at edk2.groups.io; Ni, Ray
Subject: Re: [edk2-devel] [PATCH] MdeModulePkg/XhciDxe: Fix Aligned Page Allocation

Hello Hao,

Were you able to validate the PEI change I sent last week?

Thanks

Ashish

________________________________

From: Ashish Singhal <ashishsingha at nvidia.com>
Sent: Friday, October 11, 2019 12:07 PM
To: Wu, Hao A <hao.a.wu at intel.com>; devel at edk2.groups.io <devel at edk2.groups.io>; Ni, Ray <ray.ni at intel.com>
Subject: Re: [edk2-devel] [PATCH] MdeModulePkg/XhciDxe: Fix Aligned Page Allocation

Patch set 2 has been submitted for review.

Thanks

Ashish

________________________________

From: Wu, Hao A <hao.a.wu at intel.com>
Sent: Thursday, October 10, 2019 11:53 PM
To: devel at edk2.groups.io <devel at edk2.groups.io>; Ashish Singhal <ashishsingha at nvidia.com>; Ni, Ray <ray.ni at intel.com>
Subject: RE: [edk2-devel] [PATCH] MdeModulePkg/XhciDxe: Fix Aligned Page Allocation

Hello Ashish,

I think the IOMMU feature is added for the protection of FW integrity against

HW devices, which is the motivation to use IOMMU PPI for memory allocation.

The fix is easy for the DXE part since the IOMMU part has been integrated to the

implementation of the PciIo protocol.

As for the XhciPei case, my thought is that a new helper function (maybe called

'IoMmuAllocateAlignedBuffer') can be added in DmaMem.c file. The main differece

between IoMmuAllocateAlignedBuffer() and existing IoMmuAllocateBuffer() will be:

1. If IOMMU PPI exists, mIoMmu->AllocateBuffer() should be called with bigger

number of pages for alignment and mIoMmu->FreeBuffer() can be called right after

to free the unused pages.

2. If IOMMU PPI does not exist, this case will fall back to a similar fix for

the DXE case.

Ideally, IoMmuFreeBuffer() can be reused to free the aligned buffer.

Please help to raise if you observe any open for the above proposal, thanks.

Best Regards,

Hao Wu

From: devel at edk2.groups.io [mailto:devel at edk2.groups.io] On Behalf Of Ashish Singhal
Sent: Friday, October 11, 2019 11:30 AM
To: Wu, Hao A; devel at edk2.groups.io; Ni, Ray
Subject: Re: [edk2-devel] [PATCH] MdeModulePkg/XhciDxe: Fix Aligned Page Allocation

Hello Hao,

What is your motivation towards using IoMMUPei for memory allocation now instead of Pei Services? The fix would be simple if we just change the number of pages needed to accommodate for the alignment. The call to free the pages would not do anything.

If we use IoMMUPei, we may need to change function definition for allocate to return how many pages were allocated for each call so that freeing can be done correctly as well. This may need more refactoring of the code that initially thought of.

Thanks

Ashish

From: Wu, Hao A <hao.a.wu at intel.com>
Sent: Thursday, October 10, 2019 9:00 PM
To: devel at edk2.groups.io; Ashish Singhal <ashishsingha at nvidia.com>; Ni, Ray <ray.ni at intel.com>
Subject: RE: [edk2-devel] [PATCH] MdeModulePkg/XhciDxe: Fix Aligned Page Allocation

Thanks Ashish,

Please help to send out the fix for XhciPei in a separate patch as well.

I can help to see if verification can be done on my side.

Best Regards,

Hao Wu

From: devel at edk2.groups.io<mailto:devel at edk2.groups.io> [mailto:devel at edk2.groups.io] On Behalf Of Ashish Singhal
Sent: Friday, October 11, 2019 1:51 AM
To: Wu, Hao A; devel at edk2.groups.io<mailto:devel at edk2.groups.io>; Ni, Ray
Subject: Re: [edk2-devel] [PATCH] MdeModulePkg/XhciDxe: Fix Aligned Page Allocation

Hello Hao,

I agree that for completeness we should fix the issue in both DXE as well as PEI but on my target, we do not have any PEI phase for me to be able to verify any change that I will be making. If you still want, I can still make the change so that someone else can verify or we can have someone else fix PEI and push my change meanwhile to fix the issue in DXE.

Thanks

Ashish

________________________________

From: Wu, Hao A <hao.a.wu at intel.com<mailto:hao.a.wu at intel.com>>
Sent: Wednesday, October 9, 2019 8:09 PM
To: Ashish Singhal <ashishsingha at nvidia.com<mailto:ashishsingha at nvidia.com>>; devel at edk2.groups.io<mailto:devel at edk2.groups.io> <devel at edk2.groups.io<mailto:devel at edk2.groups.io>>; Ni, Ray <ray.ni at intel.com<mailto:ray.ni at intel.com>>
Subject: RE: [PATCH] MdeModulePkg/XhciDxe: Fix Aligned Page Allocation

> -----Original Message-----
> From: Ashish Singhal [mailto:ashishsingha at nvidia.com]
> Sent: Thursday, October 10, 2019 9:58 AM
> To: Wu, Hao A; devel at edk2.groups.io<mailto:devel at edk2.groups.io>; Ni, Ray
> Subject: RE: [PATCH] MdeModulePkg/XhciDxe: Fix Aligned Page Allocation
>
> Hello Hao,
>
> I can see that the PEI also has the same issue and take a look at that as well
> but I have no way to verify that as we are not using it. For the change I have
> made in DXE, I have verified it with an alignment of 4K and 64K.

Is it possible for you to verify the PEI case with a test PEI module that
performs read operation to a USB storage device? I think this will trigger
the affecting codes.

In my opinion, it would be better for the fix to be complete.

Best Regards,
Hao Wu

>
> Thanks
> Ashish
>
> -----Original Message-----
> From: Wu, Hao A <hao.a.wu at intel.com<mailto:hao.a.wu at intel.com>>
> Sent: Wednesday, October 9, 2019 7:33 PM
> To: Ashish Singhal <ashishsingha at nvidia.com<mailto:ashishsingha at nvidia.com>>; devel at edk2.groups.io<mailto:devel at edk2.groups.io>; Ni,
> Ray <ray.ni at intel.com<mailto:ray.ni at intel.com>>
> Subject: RE: [PATCH] MdeModulePkg/XhciDxe: Fix Aligned Page Allocation
>
> > -----Original Message-----
> > From: Ashish Singhal [mailto:ashishsingha at nvidia.com]
> > Sent: Thursday, October 10, 2019 1:02 AM
> > To: devel at edk2.groups.io<mailto:devel at edk2.groups.io>; Wu, Hao A; Ni, Ray
> > Cc: Ashish Singhal
> > Subject: [PATCH] MdeModulePkg/XhciDxe: Fix Aligned Page Allocation
> >
> > While allocating pages aligned at an alignment higher than 4K,
> > allocate memory taking into consideration the padding required for
> > that alignment. The calls to free pages takes care of this already.
> >
> > Signed-off-by: Ashish Singhal <ashishsingha at nvidia.com<mailto:ashishsingha at nvidia.com>>
> > ---
> >  MdeModulePkg/Bus/Pci/XhciDxe/UsbHcMem.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/MdeModulePkg/Bus/Pci/XhciDxe/UsbHcMem.c
> > b/MdeModulePkg/Bus/Pci/XhciDxe/UsbHcMem.c
> > index fd79988..aa69c47 100644
> > --- a/MdeModulePkg/Bus/Pci/XhciDxe/UsbHcMem.c
> > +++ b/MdeModulePkg/Bus/Pci/XhciDxe/UsbHcMem.c
> > @@ -656,7 +656,7 @@ UsbHcAllocateAlignedPages (
> >                        PciIo,
> >                        AllocateAnyPages,
> >                        EfiBootServicesData,
> > -                      Pages,
> > +                      RealPages,
> >                        &Memory,
> >                        0
> >                        );
>
>
> Hello,
>
> The change looks good to me.
>
> Just a couple of things to confirm:
>
> 1. I think there is a similar case within the XhciPei driver Could you help to
> resolve it as well?
>
> I think for the PEI counterpart you may need to update both
> UsbHcAllocateAlignedPages() and UsbHcFreeAlignedPages(), since the
> IOMMU helper functions like IoMmuAllocateBuffer() and IoMmuFreeBuffer()
> might not be suitable now. Instead, I think services in the IoMmu PPI can be
> used.
>
> 2. Could you help to provide the information on what test has been done for
> the proposed patch?
>
> Thanks in advance.
>
> Best Regards,
> Hao Wu
>
>
> > --
> > 2.7.4
>
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