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Message-ID: <1a12ce97-2e21-0b28-b852-31f21626c378@huawei.com>
Date: Tue, 21 May 2019 13:59:06 +0100
From: John Garry <john.garry@...wei.com>
To: Zhen Lei <thunder.leizhen@...wei.com>,
Jean-Philippe Brucker <jean-philippe.brucker@....com>,
Robin Murphy <robin.murphy@....com>,
"Will Deacon" <will.deacon@....com>,
Joerg Roedel <joro@...tes.org>,
Jonathan Corbet <corbet@....net>,
linux-doc <linux-doc@...r.kernel.org>,
Sebastian Ott <sebott@...ux.ibm.com>,
Gerald Schaefer <gerald.schaefer@...ibm.com>,
"Martin Schwidefsky" <schwidefsky@...ibm.com>,
Heiko Carstens <heiko.carstens@...ibm.com>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Paul Mackerras <paulus@...ba.org>,
"Michael Ellerman" <mpe@...erman.id.au>,
Tony Luck <tony.luck@...el.com>,
Fenghua Yu <fenghua.yu@...el.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
"H . Peter Anvin" <hpa@...or.com>,
David Woodhouse <dwmw2@...radead.org>,
iommu <iommu@...ts.linux-foundation.org>,
linux-kernel <linux-kernel@...r.kernel.org>,
linux-s390 <linux-s390@...r.kernel.org>,
linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
x86 <x86@...nel.org>, linux-ia64 <linux-ia64@...r.kernel.org>
CC: Hanjun Guo <guohanjun@...wei.com>, Linuxarm <linuxarm@...wei.com>
Subject: Re: [PATCH v7 1/1] iommu: enhance IOMMU dma mode build options
On 20/05/2019 14:59, Zhen Lei wrote:
> First, add build option IOMMU_DEFAULT_{LAZY|STRICT}, so that we have the
> opportunity to set {lazy|strict} mode as default at build time. Then put
> the three config options in an choice, make people can only choose one of
> the three at a time.
>
> The default IOMMU dma modes on each ARCHs have no change.
>
> Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>
Apart from more minor comments, FWIW:
Reviewed-by: John Garry <john.garry@...wei.com>
> ---
> arch/ia64/kernel/pci-dma.c | 2 +-
> arch/powerpc/platforms/powernv/pci-ioda.c | 3 ++-
> arch/s390/pci/pci_dma.c | 2 +-
> arch/x86/kernel/pci-dma.c | 7 ++---
> drivers/iommu/Kconfig | 44 ++++++++++++++++++++++++++-----
> drivers/iommu/amd_iommu_init.c | 3 ++-
> drivers/iommu/intel-iommu.c | 2 +-
> drivers/iommu/iommu.c | 3 ++-
> 8 files changed, 48 insertions(+), 18 deletions(-)
>
> diff --git a/arch/ia64/kernel/pci-dma.c b/arch/ia64/kernel/pci-dma.c
> index fe988c49f01ce6a..655511dbf3c3b34 100644
> --- a/arch/ia64/kernel/pci-dma.c
> +++ b/arch/ia64/kernel/pci-dma.c
> @@ -22,7 +22,7 @@
> int force_iommu __read_mostly;
> #endif
>
> -int iommu_pass_through;
> +int iommu_pass_through = IS_ENABLED(CONFIG_IOMMU_DEFAULT_PASSTHROUGH);
As commented privately, I could never see this set for ia64, and it
seems to exist just to keep the linker happy. Anyway, I am not sure if
ever suitable to be set.
>
> static int __init pci_iommu_init(void)
> {
> diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
> index 3ead4c237ed0ec9..383e082a9bb985c 100644
> --- a/arch/powerpc/platforms/powernv/pci-ioda.c
> +++ b/arch/powerpc/platforms/powernv/pci-ioda.c
> @@ -85,7 +85,8 @@ void pe_level_printk(const struct pnv_ioda_pe *pe, const char *level,
> va_end(args);
> }
>
> -static bool pnv_iommu_bypass_disabled __read_mostly;
> +static bool pnv_iommu_bypass_disabled __read_mostly =
> + !IS_ENABLED(CONFIG_IOMMU_DEFAULT_PASSTHROUGH);
> static bool pci_reset_phbs __read_mostly;
>
> static int __init iommu_setup(char *str)
> diff --git a/arch/s390/pci/pci_dma.c b/arch/s390/pci/pci_dma.c
> index 9e52d1527f71495..784ad1e0acecfb1 100644
> --- a/arch/s390/pci/pci_dma.c
> +++ b/arch/s390/pci/pci_dma.c
> @@ -17,7 +17,7 @@
>
> static struct kmem_cache *dma_region_table_cache;
> static struct kmem_cache *dma_page_table_cache;
> -static int s390_iommu_strict;
> +static int s390_iommu_strict = IS_ENABLED(CONFIG_IOMMU_DEFAULT_STRICT);
>
> static int zpci_refresh_global(struct zpci_dev *zdev)
> {
> diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
> index d460998ae828514..fb2bab42a0a3173 100644
> --- a/arch/x86/kernel/pci-dma.c
> +++ b/arch/x86/kernel/pci-dma.c
> @@ -43,11 +43,8 @@
> * 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
> +int iommu_pass_through __read_mostly =
> + IS_ENABLED(CONFIG_IOMMU_DEFAULT_PASSTHROUGH);
>
> extern struct iommu_table_entry __iommu_table[], __iommu_table_end[];
>
> diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
> index 6f07f3b21816c64..8a1f1793cde76b4 100644
> --- a/drivers/iommu/Kconfig
> +++ b/drivers/iommu/Kconfig
> @@ -74,17 +74,47 @@ config IOMMU_DEBUGFS
> debug/iommu directory, and then populate a subdirectory with
> entries as required.
>
> -config IOMMU_DEFAULT_PASSTHROUGH
> - bool "IOMMU passthrough by default"
> +choice
> + prompt "IOMMU default DMA mode"
> depends on IOMMU_API
> - help
> - Enable passthrough by default, removing the need to pass in
> - iommu.passthrough=on or iommu=pt through command line. If this
> - is enabled, you can still disable with iommu.passthrough=off
> - or iommu=nopt depending on the architecture.
> + default IOMMU_DEFAULT_PASSTHROUGH if (PPC_POWERNV && PCI)
> + default IOMMU_DEFAULT_LAZY if (AMD_IOMMU || INTEL_IOMMU || S390_IOMMU)
> + default IOMMU_DEFAULT_STRICT
> + help
> + This option allows IOMMU DMA mode to be chose at build time, to
I'd say /s/allows IOMMU/allows an IOMMU/, /s/chose/chosen/
> + override the default DMA mode of each ARCHs, removing the need to
ARCHs should be singular
> + pass in kernel parameters through command line. You can still use
> + ARCHs specific boot options to override this option again.
> +
> +config IOMMU_DEFAULT_PASSTHROUGH
> + bool "passthrough"
> + help
> + In this mode, the DMA access through IOMMU without any addresses
> + translation. That means, the wrong or illegal DMA access can not
> + be caught, no error information will be reported.
>
> If unsure, say N here.
>
> +config IOMMU_DEFAULT_LAZY
> + bool "lazy"
> + help
> + Support lazy mode, where for every IOMMU DMA unmap operation, the
> + flush operation of IOTLB and the free operation of IOVA are deferred.
> + They are only guaranteed to be done before the related IOVA will be
> + reused.
> +
> +config IOMMU_DEFAULT_STRICT
> + bool "strict"
> + help
> + For every IOMMU DMA unmap operation, the flush operation of IOTLB and
> + the free operation of IOVA are guaranteed to be done in the unmap
> + function.
> +
> + This mode is safer than the two above, but it maybe slower in some
> + high performace scenarios.
> +
> +endchoice
> +
> config OF_IOMMU
> def_bool y
> depends on OF && IOMMU_API
> diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
> index ff40ba758cf365e..16c02b08adb4cb2 100644
> --- a/drivers/iommu/amd_iommu_init.c
> +++ b/drivers/iommu/amd_iommu_init.c
> @@ -166,7 +166,8 @@ struct ivmd_header {
> to handle */
> LIST_HEAD(amd_iommu_unity_map); /* a list of required unity mappings
> we find in ACPI */
> -bool amd_iommu_unmap_flush; /* if true, flush on every unmap */
> +bool amd_iommu_unmap_flush = IS_ENABLED(CONFIG_IOMMU_DEFAULT_STRICT);
> + /* if true, flush on every unmap */
>
> LIST_HEAD(amd_iommu_list); /* list of all AMD IOMMUs in the
> system */
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index 28cb713d728ceef..0c3cc716210f35a 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -362,7 +362,7 @@ static int domain_detach_iommu(struct dmar_domain *domain,
>
> static int dmar_map_gfx = 1;
> static int dmar_forcedac;
> -static int intel_iommu_strict;
> +static int intel_iommu_strict = IS_ENABLED(CONFIG_IOMMU_DEFAULT_STRICT);
> static int intel_iommu_superpage = 1;
> static int intel_iommu_sm;
> static int iommu_identity_mapping;
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 109de67d5d727c2..0ec5952ac60e2a3 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -43,7 +43,8 @@
> #else
> static unsigned int iommu_def_domain_type = IOMMU_DOMAIN_DMA;
> #endif
> -static bool iommu_dma_strict __read_mostly = true;
> +static bool iommu_dma_strict __read_mostly =
> + IS_ENABLED(CONFIG_IOMMU_DEFAULT_STRICT);
>
> struct iommu_group {
> struct kobject kobj;
> --
> 1.8.3
>
>
>
> .
>
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