[PATCH kernel 2/2] powerpc/pseries/dma: Enable swiotlb
Thiago Jung Bauermann
bauerman at linux.ibm.com
Sat May 11 08:41:50 AEST 2019
Hello Alexey,
Thanks!
I have similar changes in my "Secure Virtual Machine Enablement"
patches, which I am currently preparing for posting again real soon now.
This is the last version:
https://lore.kernel.org/linuxppc-dev/20180824162535.22798-1-bauerman@linux.ibm.com/
Alexey Kardashevskiy <aik at ozlabs.ru> writes:
> So far the pseries platforms has always been using IOMMU making SWIOTLB
> unnecessary. Now we want secure guests which means devices can only
> access certain areas of guest physical memory; we are going to use
> SWIOTLB for this purpose.
>
> This allows SWIOTLB for pseries. By default there is no change in behavior.
>
> This enables SWIOTLB when the "swiotlb" kernel parameter is set to "force".
>
> With the SWIOTLB enabled, the kernel creates a directly mapped DMA window
> (using the usual DDW mechanism) and implements SWIOTLB on top of that.
>
> Signed-off-by: Alexey Kardashevskiy <aik at ozlabs.ru>
> ---
> arch/powerpc/platforms/pseries/setup.c | 5 +++++
> arch/powerpc/platforms/pseries/Kconfig | 1 +
> 2 files changed, 6 insertions(+)
>
> diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c
> index e4f0dfd4ae33..30d72b587ac5 100644
> --- a/arch/powerpc/platforms/pseries/setup.c
> +++ b/arch/powerpc/platforms/pseries/setup.c
> @@ -42,6 +42,7 @@
> #include <linux/of.h>
> #include <linux/of_pci.h>
> #include <linux/memblock.h>
> +#include <linux/swiotlb.h>
>
> #include <asm/mmu.h>
> #include <asm/processor.h>
> @@ -71,6 +72,7 @@
> #include <asm/isa-bridge.h>
> #include <asm/security_features.h>
> #include <asm/asm-const.h>
> +#include <asm/swiotlb.h>
>
> #include "pseries.h"
> #include "../../../../drivers/pci/pci.h"
> @@ -797,6 +799,9 @@ static void __init pSeries_setup_arch(void)
> }
>
> ppc_md.pcibios_root_bridge_prepare = pseries_root_bridge_prepare;
> +
> + if (swiotlb_force == SWIOTLB_FORCE)
> + ppc_swiotlb_enable = 1;
> }
Yep! I have this here, enabled when booting as a secure guest:
https://lore.kernel.org/linuxppc-dev/20180824162535.22798-6-bauerman@linux.ibm.com/
And also another patch which makes it so that if booting as a secure
guest it acts as if the swiotlb kernel parameter was set to force:
https://lore.kernel.org/linuxppc-dev/20180824162535.22798-11-bauerman@linux.ibm.com/
> static void pseries_panic(char *str)
> diff --git a/arch/powerpc/platforms/pseries/Kconfig b/arch/powerpc/platforms/pseries/Kconfig
> index 9c6b3d860518..b9e8b608de01 100644
> --- a/arch/powerpc/platforms/pseries/Kconfig
> +++ b/arch/powerpc/platforms/pseries/Kconfig
> @@ -23,6 +23,7 @@ config PPC_PSERIES
> select ARCH_RANDOM
> select PPC_DOORBELL
> select FORCE_SMP
> + select SWIOTLB
> default y
>
> config PPC_SPLPAR
I put this in a PPC_SVM config option:
https://lore.kernel.org/linuxppc-dev/20180824162535.22798-3-bauerman@linux.ibm.com/
--
Thiago Jung Bauermann
IBM Linux Technology Center
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