linux-kernel - Re: [PATCH 2/2] x86/pci: Clean up usage of X86_DEV_DMA

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Message-ID: <20190410214500.GK256045@google.com>
Date:   Wed, 10 Apr 2019 16:45:01 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     Christoph Hellwig <hch@....de>, linux-pci@...r.kernel.org,
        x86@...nel.org, linux-kernel@...r.kernel.org,
        Keith Busch <keith.busch@...el.com>,
        Jonathan Derrick <jonathan.derrick@...el.com>
Subject: Re: [PATCH 2/2] x86/pci: Clean up usage of X86_DEV_DMA_OPS

[+cc Keith, Jonathan (VMD guys)]

I'm OK with this from a PCI perspective.  It would be nice if

  dma_domain_list
  dma_domain_list_lock
  add_dma_domain()
  del_dma_domain()
  set_dma_domain_ops()

could all be moved to vmd.c, since they're really only used there.

But we don't really have a good way to call host bridge-specific code
like set_dma_domain_ops() except via pcibios_add_device().  Someday
maybe pcibios_add_device() will become a host bridge method.

Acked-by: Bjorn Helgaas <bhelgaas@...gle.com>


On Wed, Apr 10, 2019 at 10:16:17AM +0200, Ingo Molnar wrote:
> (+Cc. Patch quoted below. Acked-by from an x86 perspective.)
> 
> * Christoph Hellwig <hch@....de> wrote:
> 
> > We have supported per-device dma_map_ops in generic code for a long
> > time, and this symbol just guards the inclusion of the dma_map_ops
> > registry used for vmd.  Stop enabling it for anything but vmd.
> > 
> > Signed-off-by: Christoph Hellwig <hch@....de>
> > ---
> >  arch/x86/Kconfig               | 3 ---
> >  drivers/misc/mic/Kconfig       | 4 ++--
> >  drivers/pci/controller/Kconfig | 1 +
> >  drivers/pci/controller/vmd.c   | 7 -------
> >  4 files changed, 3 insertions(+), 12 deletions(-)
> > 
> > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> > index 38c62ff8a3f0..d8e2e6519a61 100644
> > --- a/arch/x86/Kconfig
> > +++ b/arch/x86/Kconfig
> > @@ -28,7 +28,6 @@ config X86_64
> >  	select MODULES_USE_ELF_RELA
> >  	select NEED_DMA_MAP_STATE
> >  	select SWIOTLB
> > -	select X86_DEV_DMA_OPS
> >  	select ARCH_HAS_SYSCALL_WRAPPER
> >  
> >  #
> > @@ -703,7 +702,6 @@ config STA2X11
> >  	bool "STA2X11 Companion Chip Support"
> >  	depends on X86_32_NON_STANDARD && PCI
> >  	select ARCH_HAS_PHYS_TO_DMA
> > -	select X86_DEV_DMA_OPS
> >  	select SWIOTLB
> >  	select MFD_STA2X11
> >  	select GPIOLIB
> > @@ -2877,7 +2875,6 @@ config HAVE_ATOMIC_IOMAP
> >  
> >  config X86_DEV_DMA_OPS
> >  	bool
> > -	depends on X86_64 || STA2X11
> >  
> >  config HAVE_GENERIC_GUP
> >  	def_bool y
> > diff --git a/drivers/misc/mic/Kconfig b/drivers/misc/mic/Kconfig
> > index 242dcee14689..6736f72cc14a 100644
> > --- a/drivers/misc/mic/Kconfig
> > +++ b/drivers/misc/mic/Kconfig
> > @@ -4,7 +4,7 @@ comment "Intel MIC Bus Driver"
> >  
> >  config INTEL_MIC_BUS
> >  	tristate "Intel MIC Bus Driver"
> > -	depends on 64BIT && PCI && X86 && X86_DEV_DMA_OPS
> > +	depends on 64BIT && PCI && X86
> >  	help
> >  	  This option is selected by any driver which registers a
> >  	  device or driver on the MIC Bus, such as CONFIG_INTEL_MIC_HOST,
> > @@ -21,7 +21,7 @@ comment "SCIF Bus Driver"
> >  
> >  config SCIF_BUS
> >  	tristate "SCIF Bus Driver"
> > -	depends on 64BIT && PCI && X86 && X86_DEV_DMA_OPS
> > +	depends on 64BIT && PCI && X86
> >  	help
> >  	  This option is selected by any driver which registers a
> >  	  device or driver on the SCIF Bus, such as CONFIG_INTEL_MIC_HOST
> > diff --git a/drivers/pci/controller/Kconfig b/drivers/pci/controller/Kconfig
> > index 6012f3059acd..011c57cae4b0 100644
> > --- a/drivers/pci/controller/Kconfig
> > +++ b/drivers/pci/controller/Kconfig
> > @@ -267,6 +267,7 @@ config PCIE_TANGO_SMP8759
> >  
> >  config VMD
> >  	depends on PCI_MSI && X86_64 && SRCU
> > +	select X86_DEV_DMA_OPS
> >  	tristate "Intel Volume Management Device Driver"
> >  	---help---
> >  	  Adds support for the Intel Volume Management Device (VMD). VMD is a
> > diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
> > index cf6816b55b5e..999a5509e57e 100644
> > --- a/drivers/pci/controller/vmd.c
> > +++ b/drivers/pci/controller/vmd.c
> > @@ -95,10 +95,8 @@ struct vmd_dev {
> >  	struct irq_domain	*irq_domain;
> >  	struct pci_bus		*bus;
> >  
> > -#ifdef CONFIG_X86_DEV_DMA_OPS
> >  	struct dma_map_ops	dma_ops;
> >  	struct dma_domain	dma_domain;
> > -#endif
> >  };
> >  
> >  static inline struct vmd_dev *vmd_from_bus(struct pci_bus *bus)
> > @@ -293,7 +291,6 @@ static struct msi_domain_info vmd_msi_domain_info = {
> >  	.chip		= &vmd_msi_controller,
> >  };
> >  
> > -#ifdef CONFIG_X86_DEV_DMA_OPS
> >  /*
> >   * VMD replaces the requester ID with its own.  DMA mappings for devices in a
> >   * VMD domain need to be mapped for the VMD, not the device requiring
> > @@ -438,10 +435,6 @@ static void vmd_setup_dma_ops(struct vmd_dev *vmd)
> >  	add_dma_domain(domain);
> >  }
> >  #undef ASSIGN_VMD_DMA_OPS
> > -#else
> > -static void vmd_teardown_dma_ops(struct vmd_dev *vmd) {}
> > -static void vmd_setup_dma_ops(struct vmd_dev *vmd) {}
> > -#endif
> >  
> >  static char __iomem *vmd_cfg_addr(struct vmd_dev *vmd, struct pci_bus *bus,
> >  				  unsigned int devfn, int reg, int len)
> > -- 
> > 2.20.1
> >