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

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Date:   Wed, 10 Apr 2019 10:16:17 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     Christoph Hellwig <hch@....de>,
        Bjorn Helgaas <bhelgaas@...gle.com>, linux-pci@...r.kernel.org
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] x86/pci: Clean up usage of X86_DEV_DMA_OPS



(+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
>