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Message-ID: <Y08HgXqvNSpTUgWe@a4bf019067fa.jf.intel.com>
Date: Tue, 18 Oct 2022 13:07:29 -0700
From: Ashok Raj <ashok.raj@...el.com>
To: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
CC: Dave Hansen <dave.hansen@...ux.intel.com>,
Andy Lutomirski <luto@...nel.org>,
Peter Zijlstra <peterz@...radead.org>, <x86@...nel.org>,
Kostya Serebryany <kcc@...gle.com>,
Andrey Ryabinin <ryabinin.a.a@...il.com>,
Andrey Konovalov <andreyknvl@...il.com>,
Alexander Potapenko <glider@...gle.com>,
Taras Madan <tarasmadan@...gle.com>,
Dmitry Vyukov <dvyukov@...gle.com>,
"H . J . Lu" <hjl.tools@...il.com>,
Andi Kleen <ak@...ux.intel.com>,
Rick Edgecombe <rick.p.edgecombe@...el.com>,
"Bharata B Rao" <bharata@....com>,
Jacob Pan <jacob.jun.pan@...ux.intel.com>,
<linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
Ashok Raj <ashok.raj@...el.com>
Subject: Re: [PATCHv10 10/15] x86/mm, iommu/sva: Make LAM and SVM mutually
exclusive
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@...el.com>
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
> ---
> 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
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