| Message ID | 20190327150030.11112-1-thunder.leizhen@huawei.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v2,1/1] iommu: Add config option to set lazy mode as default | expand |
On 27/03/2019 15:00, Zhen Lei wrote: > This allows the default behaviour to be controlled by a kernel config > option instead of changing the command line for the kernel to include > "iommu.strict=0" on ARM64 where this is desired. > > This is similar to CONFIG_IOMMU_DEFAULT_PASSTHROUGH. > > Note: At present, intel_iommu, amd_iommu and s390_iommu use lazy mode as > default, so there is no need to add code for them. That seems a bit self-contradictory - if there's a real need for TLB flush behaviour to be statically configurable and not command-line-based then why should users of other architectures be exempt? > Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> > --- > drivers/iommu/Kconfig | 14 ++++++++++++++ > drivers/iommu/iommu.c | 5 +++++ > 2 files changed, 19 insertions(+) > > diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig > index 6f07f3b21816c64..5daa110d0e83a07 100644 > --- a/drivers/iommu/Kconfig > +++ b/drivers/iommu/Kconfig > @@ -85,6 +85,20 @@ config IOMMU_DEFAULT_PASSTHROUGH > > If unsure, say N here. > > +config IOMMU_DMA_DEFAULT_LAZY_MODE > + bool "IOMMU DMA use lazy mode to flush IOTLB and free IOVA" > + depends on IOMMU_API > + 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. Removing the need to pass in kernel parameters through > + command line. For example, iommu.strict=0 on ARM64. If this is > + enabled, you can still disable with kernel parameters, such as > + iommu.strict=1 depending on the architecture. > + > + If unsure, say N here. > + > config OF_IOMMU > def_bool y > depends on OF && IOMMU_API > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > index 33a982e33716369..5acb98e79b5b32d 100644 > --- a/drivers/iommu/iommu.c > +++ b/drivers/iommu/iommu.c > @@ -43,7 +43,12 @@ > #else > static unsigned int iommu_def_domain_type = IOMMU_DOMAIN_DMA; > #endif > + > +#ifdef CONFIG_IOMMU_DMA_DEFAULT_LAZY_MODE > +static bool iommu_dma_strict __read_mostly; > +#else > static bool iommu_dma_strict __read_mostly = true; > +#endif For a straightforward boolean, you can simply do: static bool foo = IS_ENABLED(CONFIG_FOO); but that said, I'm still not particularly convinced that there are a significant number of users in a position to build and install a custom kernel but not edit /etc/default/grub, and who really value the combination of less performance than passthrough with less isolation than strict. It's also not necessarily obvious to the user how this interacts with IOMMU_DEFAULT_PASSTHROUGH, so if we really do go down this route, maybe it would be better to refactor the whole lot into a single selection of something like IOMMU_DEFAULT_MODE anyway. Robin. > > struct iommu_callback_data { > const struct iommu_ops *ops; > -- > 1.8.3 > >
On 2019/3/28 3:18, Robin Murphy wrote: > On 27/03/2019 15:00, Zhen Lei wrote: >> This allows the default behaviour to be controlled by a kernel config >> option instead of changing the command line for the kernel to include >> "iommu.strict=0" on ARM64 where this is desired. >> >> This is similar to CONFIG_IOMMU_DEFAULT_PASSTHROUGH. >> >> Note: At present, intel_iommu, amd_iommu and s390_iommu use lazy mode as >> default, so there is no need to add code for them. > > That seems a bit self-contradictory - if there's a real need for TLB flush behaviour to be statically configurable and not command-line-based then why should users of other architectures be exempt? Yes，you're right. I will make this configuration to be effective for other architectures. BTW, can you give some opinion about below patches? https://patchwork.kernel.org/patch/10857601/ > >> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> >> --- >> drivers/iommu/Kconfig | 14 ++++++++++++++ >> drivers/iommu/iommu.c | 5 +++++ >> 2 files changed, 19 insertions(+) >> >> diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig >> index 6f07f3b21816c64..5daa110d0e83a07 100644 >> --- a/drivers/iommu/Kconfig >> +++ b/drivers/iommu/Kconfig >> @@ -85,6 +85,20 @@ config IOMMU_DEFAULT_PASSTHROUGH >> >> If unsure, say N here. >> >> +config IOMMU_DMA_DEFAULT_LAZY_MODE >> + bool "IOMMU DMA use lazy mode to flush IOTLB and free IOVA" >> + depends on IOMMU_API >> + 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. Removing the need to pass in kernel parameters through >> + command line. For example, iommu.strict=0 on ARM64. If this is >> + enabled, you can still disable with kernel parameters, such as >> + iommu.strict=1 depending on the architecture. >> + >> + If unsure, say N here. >> + >> config OF_IOMMU >> def_bool y >> depends on OF && IOMMU_API >> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c >> index 33a982e33716369..5acb98e79b5b32d 100644 >> --- a/drivers/iommu/iommu.c >> +++ b/drivers/iommu/iommu.c >> @@ -43,7 +43,12 @@ >> #else >> static unsigned int iommu_def_domain_type = IOMMU_DOMAIN_DMA; >> #endif >> + >> +#ifdef CONFIG_IOMMU_DMA_DEFAULT_LAZY_MODE >> +static bool iommu_dma_strict __read_mostly; >> +#else >> static bool iommu_dma_strict __read_mostly = true; >> +#endif > > For a straightforward boolean, you can simply do: > > static bool foo = IS_ENABLED(CONFIG_FOO); > > but that said, I'm still not particularly convinced that there are a significant number of users in a position to build and install a custom kernel but not edit /etc/default/grub, and who really value the combination of less performance than passthrough with less isolation than strict. > > It's also not necessarily obvious to the user how this interacts with IOMMU_DEFAULT_PASSTHROUGH, so if we really do go down this route, maybe it would be better to refactor the whole lot into a single selection of something like IOMMU_DEFAULT_MODE anyway. > > Robin. > >> >> struct iommu_callback_data { >> const struct iommu_ops *ops; >> -- >> 1.8.3 >> >> > > . > -- Thanks! BestRegards
diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig index 6f07f3b21816c64..5daa110d0e83a07 100644 --- a/drivers/iommu/Kconfig +++ b/drivers/iommu/Kconfig @@ -85,6 +85,20 @@ config IOMMU_DEFAULT_PASSTHROUGH If unsure, say N here. +config IOMMU_DMA_DEFAULT_LAZY_MODE + bool "IOMMU DMA use lazy mode to flush IOTLB and free IOVA" + depends on IOMMU_API + 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. Removing the need to pass in kernel parameters through + command line. For example, iommu.strict=0 on ARM64. If this is + enabled, you can still disable with kernel parameters, such as + iommu.strict=1 depending on the architecture. + + If unsure, say N here. + config OF_IOMMU def_bool y depends on OF && IOMMU_API diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index 33a982e33716369..5acb98e79b5b32d 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -43,7 +43,12 @@ #else static unsigned int iommu_def_domain_type = IOMMU_DOMAIN_DMA; #endif + +#ifdef CONFIG_IOMMU_DMA_DEFAULT_LAZY_MODE +static bool iommu_dma_strict __read_mostly; +#else static bool iommu_dma_strict __read_mostly = true; +#endif struct iommu_callback_data { const struct iommu_ops *ops;
This allows the default behaviour to be controlled by a kernel config option instead of changing the command line for the kernel to include "iommu.strict=0" on ARM64 where this is desired. This is similar to CONFIG_IOMMU_DEFAULT_PASSTHROUGH. Note: At present, intel_iommu, amd_iommu and s390_iommu use lazy mode as default, so there is no need to add code for them. Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> --- drivers/iommu/Kconfig | 14 ++++++++++++++ drivers/iommu/iommu.c | 5 +++++ 2 files changed, 19 insertions(+) -- 1.8.3