Re: [PATCH 2/2] IOMMU/MMU: Adjust low level functions for VT-d Device-TLB flush error.

From: "Xu, Quan" <quan.xu@intel.com>
To: "Tian, Kevin" <kevin.tian@intel.com>
Cc: "Nakajima, Jun" <jun.nakajima@intel.com>,
	Keir Fraser <keir@xen.org>, Jan Beulich <jbeulich@suse.com>,
	George Dunlap <george.dunlap@eu.citrix.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Dario Faggioli <dario.faggioli@citrix.com>,
	"xen-devel@lists.xen.org" <xen-devel@lists.xen.org>,
	Julien Grall <julien.grall@arm.com>,
	Stefano Stabellini <stefano.stabellini@citrix.com>,
	Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
	"Wu, Feng" <feng.wu@intel.com>
Subject: Re: [PATCH 2/2] IOMMU/MMU: Adjust low level functions for VT-d Device-TLB flush error.
Date: Fri, 18 Mar 2016 02:30:06 +0000	[thread overview]
Message-ID: <945CA011AD5F084CBEA3E851C0AB28894B8670AD@SHSMSX101.ccr.corp.intel.com> (raw)
In-Reply-To: <AADFC41AFE54684AB9EE6CBC0274A5D15F7EC7CE@SHSMSX101.ccr.corp.intel.com>

On March 17, 2016 3:38pm, Tian, Kevin <kevin.tian@intel.com> wrote:
> > From: Xu, Quan
> > Sent: Thursday, March 17, 2016 2:55 PM
> >
> > Current code would be panic(), when VT-d Device-TLB flush timed out.
> > the panic() is going to be eliminated, so we must check all kinds of
> > error and all the way up the call trees.
> 
> sorry that I'm unclear what is the criteria of defining high level and low level
> functions in two patches. Could you elaborate? Once I thought you may mean
> common code and vendor specific code, however...
> 

In this patch set, it is adjusting top level functions of the call tree first, and working my way down to leaf ones.
I tried to define that top level is mainly about MMU, and the low level is mainly about IOMMU. Mixed things are in
Consideration of compiling and simplification. For high level of these call trees, IMO it is a reasonable attempt at splitting things.

> >  xen/arch/x86/mm/p2m-ept.c                     |   2 +-
> >  xen/drivers/passthrough/amd/iommu_init.c      |  12 ++-
> >  xen/drivers/passthrough/amd/pci_amd_iommu.c   |   2 +-
> >  xen/drivers/passthrough/arm/smmu.c            |  10 ++-
> >  xen/drivers/passthrough/iommu.c               |  17 ++--
> >  xen/drivers/passthrough/vtd/extern.h          |   2 +-
> >  xen/drivers/passthrough/vtd/iommu.c           | 120
> > ++++++++++++++++++--------
> >  xen/drivers/passthrough/vtd/quirks.c          |  26 +++---
> >  xen/include/asm-x86/hvm/svm/amd-iommu-proto.h |   2 +-
> >  xen/include/asm-x86/iommu.h                   |   2 +-
> >  xen/include/xen/iommu.h                       |   6 +-
> 
> Above you have general passthrough/iommu.c though most of others are
> vendor specific.
> 

 .e.g, as the 'struct iommu_ops' is common structure for arm/amd/intel.

> Then in PATCH [1/2], you have:
> 
> xen/arch/x86/acpi/power.c             | 14 +++++++++++++-
>  xen/arch/x86/mm.c                     | 13 ++++++++-----
>  xen/arch/x86/mm/p2m-ept.c             | 10 +++++++++-
>  xen/arch/x86/mm/p2m-pt.c              | 12 ++++++++++--
>  xen/common/grant_table.c              |  5 +++--
>  xen/common/memory.c                   |  5 +++--
>  xen/drivers/passthrough/iommu.c       | 16 +++++++++++-----
>  xen/drivers/passthrough/vtd/x86/vtd.c |  7 +++++--
>  xen/drivers/passthrough/x86/iommu.c   |  6 +++++-
>  xen/include/xen/iommu.h               |  6 +++---
> 
> They are also mixed.
> 

It is in Consideration of compiling and simplification. 
 e.g. for this call tree,  ...--iommu_suspend()--device_power_down()--...
 device_power_down() is in -xen/arch/x86/acpi/power.c
 iommu_suspend() is in -xen/drivers/passthrough/iommu.c

when I tried to return error code from iommu_suspend(), which is with 'void' annotation.
I need change it from 'void' to 'int', then it is unavoidable to mix things.

Any good idea? To be honest, I am very tired to at splitting things like this :).

Quan

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