linux-kernel - Re: [PATCH 06/11] x86/dma: Get rid of iommu_pass

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Message-ID: <20190820111753.GD31607@zn.tnic>
Date:   Tue, 20 Aug 2019 13:17:53 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Joerg Roedel <joro@...tes.org>
Cc:     corbet@....net, tony.luck@...el.com, fenghua.yu@...el.com,
        tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
        x86@...nel.org, linux-doc@...r.kernel.org,
        linux-ia64@...r.kernel.org, iommu@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, Thomas.Lendacky@....com,
        Suravee.Suthikulpanit@....com, Joerg Roedel <jroedel@...e.de>
Subject: Re: [PATCH 06/11] x86/dma: Get rid of iommu_pass_through

On Mon, Aug 19, 2019 at 03:22:51PM +0200, Joerg Roedel wrote:
> From: Joerg Roedel <jroedel@...e.de>
> 
> This variable has no users anymore. Remove it and tell the
> IOMMU code via its new functions about requested DMA modes.
> 
> Signed-off-by: Joerg Roedel <jroedel@...e.de>
> ---
>  arch/x86/include/asm/iommu.h |  1 -
>  arch/x86/kernel/pci-dma.c    | 20 +++-----------------
>  2 files changed, 3 insertions(+), 18 deletions(-)
> 
> diff --git a/arch/x86/include/asm/iommu.h b/arch/x86/include/asm/iommu.h
> index baedab8ac538..b91623d521d9 100644
> --- a/arch/x86/include/asm/iommu.h
> +++ b/arch/x86/include/asm/iommu.h
> @@ -4,7 +4,6 @@
>  
>  extern int force_iommu, no_iommu;
>  extern int iommu_detected;
> -extern int iommu_pass_through;
>  
>  /* 10 seconds */
>  #define DMAR_OPERATION_TIMEOUT ((cycles_t) tsc_khz*10*1000)
> diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
> index f62b498b18fb..fa4352dce491 100644
> --- a/arch/x86/kernel/pci-dma.c
> +++ b/arch/x86/kernel/pci-dma.c
> @@ -1,6 +1,7 @@
>  // SPDX-License-Identifier: GPL-2.0
>  #include <linux/dma-direct.h>
>  #include <linux/dma-debug.h>
> +#include <linux/iommu.h>
>  #include <linux/dmar.h>
>  #include <linux/export.h>
>  #include <linux/memblock.h>
> @@ -34,21 +35,6 @@ int no_iommu __read_mostly;
>  /* Set this to 1 if there is a HW IOMMU in the system */
>  int iommu_detected __read_mostly = 0;
>  
> -/*
> - * This variable becomes 1 if iommu=pt is passed on the kernel command line.
> - * If this variable is 1, IOMMU implementations do no DMA translation for
> - * devices and allow every device to access to whole physical memory. This is
> - * useful if a user wants to use an IOMMU only for KVM device assignment to
> - * guests and not for driver dma translation.
> - * It is also possible to disable by default in kernel config, and enable with
> - * iommu=nopt at boot time.
> - */
> -#ifdef CONFIG_IOMMU_DEFAULT_PASSTHROUGH
> -int iommu_pass_through __read_mostly = 1;
> -#else
> -int iommu_pass_through __read_mostly;
> -#endif
> -
>  extern struct iommu_table_entry __iommu_table[], __iommu_table_end[];
>  
>  void __init pci_iommu_alloc(void)
> @@ -120,9 +106,9 @@ static __init int iommu_setup(char *p)
>  			swiotlb = 1;
>  #endif
>  		if (!strncmp(p, "pt", 2))
> -			iommu_pass_through = 1;
> +			iommu_set_default_passthrough(true);
>  		if (!strncmp(p, "nopt", 4))
> -			iommu_pass_through = 0;
> +			iommu_set_default_translated(true);
>  
>  		gart_parse_options(p);
>  
> -- 

Reviewed-by: Borislav Petkov <bp@...e.de>

-- 
Regards/Gruss,
    Boris.

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