Re: [PATCH v18 09/15] drm/amdgpu: untag user pointers

From: Kees Cook <keescook@chromium.org>
To: Andrey Konovalov <andreyknvl@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
	kvm@vger.kernel.org, Szabolcs Nagy <Szabolcs.Nagy@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	dri-devel@lists.freedesktop.org, linux-mm@kvack.org,
	Khalid Aziz <khalid.aziz@oracle.com>,
	linux-kselftest@vger.kernel.org,
	Felix Kuehling <Felix.Kuehling@amd.com>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	Jacob Bramley <Jacob.Bramley@arm.com>,
	Leon Romanovsky <leon@kernel.org>,
	linux-rdma@vger.kernel.org, amd-gfx@lists.freedesktop.org,
	Christoph Hellwig <hch@infradead.org>,
	Jason Gunthorpe <jgg@ziepe.ca>,
	Dmitry Vyukov <dvyukov@google.com>,
	Dave Martin <Dave.Martin@arm.com>,
	Evgeniy Stepanov <eugenis@google.com>,
	linux-media@vger.kernel.org,
	Kevin Brodsky <kevin.brodsky@arm.com>,
	Ruben Ayrapetyan <Ruben.Ayrapetyan@arm.com>,
	Ramana Radhakrishnan <Ramana.Radhakrishnan@arm.com>,
	Alex Williamson <alex.williamson@redhat.com>,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	linux-arm-kernel@lists.infradead.org,
	Kostya Serebryany <kcc@google.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Yishai Hadas <yishaih@mellanox.com>,
	linux-kernel@vger.kernel.org,
	Jens Wiklander <jens.wiklander@linaro.org>,
	Lee Smith <Lee.Smith@arm.com>,
	Alexander Deucher <Alexander.Deucher@amd.com>,
	Andrew Morton <akpm@linux-foundation.org>, enh <enh@google.com>,
	Robin Murphy <robin.murphy@arm.com>,
	Christian Koenig <Christian.Koenig@amd.com>,
	Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Subject: Re: [PATCH v18 09/15] drm/amdgpu: untag user pointers
Date: Mon, 24 Jun 2019 08:00:57 -0700	[thread overview]
Message-ID: <201906240800.5677E3CF@keescook> (raw)
In-Reply-To: <1d036fc5bec4be059ee7f4f42bf7417dc44651dd.1561386715.git.andreyknvl@google.com>

On Mon, Jun 24, 2019 at 04:32:54PM +0200, Andrey Konovalov wrote:
> This patch is a part of a series that extends kernel ABI to allow to pass
> tagged user pointers (with the top byte set to something else other than
> 0x00) as syscall arguments.
> 
> In amdgpu_gem_userptr_ioctl() and amdgpu_amdkfd_gpuvm.c/init_user_pages()
> an MMU notifier is set up with a (tagged) userspace pointer. The untagged
> address should be used so that MMU notifiers for the untagged address get
> correctly matched up with the right BO. This patch untag user pointers in
> amdgpu_gem_userptr_ioctl() for the GEM case and in amdgpu_amdkfd_gpuvm_
> alloc_memory_of_gpu() for the KFD case. This also makes sure that an
> untagged pointer is passed to amdgpu_ttm_tt_get_user_pages(), which uses
> it for vma lookups.
> 
> Suggested-by: Felix Kuehling <Felix.Kuehling@amd.com>
> Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

Reviewed-by: Kees Cook <keescook@chromium.org>

-Kees

> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 2 +-
>  drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c          | 2 ++
>  2 files changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> index a6e5184d436c..5d476e9bbc43 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> @@ -1108,7 +1108,7 @@ int amdgpu_amdkfd_gpuvm_alloc_memory_of_gpu(
>  		alloc_flags = 0;
>  		if (!offset || !*offset)
>  			return -EINVAL;
> -		user_addr = *offset;
> +		user_addr = untagged_addr(*offset);
>  	} else if (flags & ALLOC_MEM_FLAGS_DOORBELL) {
>  		domain = AMDGPU_GEM_DOMAIN_GTT;
>  		alloc_domain = AMDGPU_GEM_DOMAIN_CPU;
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> index d4fcf5475464..e91df1407618 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> @@ -287,6 +287,8 @@ int amdgpu_gem_userptr_ioctl(struct drm_device *dev, void *data,
>  	uint32_t handle;
>  	int r;
>  
> +	args->addr = untagged_addr(args->addr);
> +
>  	if (offset_in_page(args->addr | args->size))
>  		return -EINVAL;
>  
> -- 
> 2.22.0.410.gd8fdbe21b5-goog
> 

-- 
Kees Cook

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