Re: [PATCHv10 10/15] x86/mm, iommu/sva: Make LAM and SVM mutually exclusive

[Ashok Raj]

On Tue, Oct 18, 2022 at 02:33:53PM +0300, Kirill A. Shutemov wrote:
> IOMMU and SVM-capable devices know nothing about LAM and only expect
> canonical addresses. Attempt to pass down tagged pointer will lead to
> address translation failure.
> 
> By default do not allow to enable both LAM and use SVM in the same
> process.
> 
> The new ARCH_FORCE_TAGGED_SVM arch_prctl() overrides the limitation.
> By using the arch_prctl() userspace takes responsibility to never pass
> tagged address to the device.

Reviewed-by: Ashok Raj <ashok.raj@xxxxxxxxx>

> 
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> ---
>  arch/x86/include/asm/mmu.h         |  6 ++++--
>  arch/x86/include/asm/mmu_context.h |  2 ++
>  arch/x86/include/uapi/asm/prctl.h  |  1 +
>  arch/x86/kernel/process_64.c       | 13 +++++++++++++
>  drivers/iommu/iommu-sva-lib.c      | 12 ++++++++++++
>  include/linux/mmu_context.h        |  4 ++++
>  6 files changed, 36 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/include/asm/mmu.h b/arch/x86/include/asm/mmu.h
> index 2fdb390040b5..cce9b32b0d6d 100644
> --- a/arch/x86/include/asm/mmu.h
> +++ b/arch/x86/include/asm/mmu.h
> @@ -9,9 +9,11 @@
>  #include <linux/bits.h>
>  
>  /* Uprobes on this MM assume 32-bit code */
> -#define MM_CONTEXT_UPROBE_IA32	BIT(0)
> +#define MM_CONTEXT_UPROBE_IA32		BIT(0)
>  /* vsyscall page is accessible on this MM */
> -#define MM_CONTEXT_HAS_VSYSCALL	BIT(1)
> +#define MM_CONTEXT_HAS_VSYSCALL		BIT(1)

Nit: Looks like the two above format changes got in here :-)

Cheers,
Ashok