From: Yan Zhao <yan.y.zhao@intel.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Jens Axboe <axboe@kernel.dk>, Felipe Balbi <balbi@kernel.org>,
amd-gfx@lists.freedesktop.org,
"Michael S. Tsirkin" <mst@redhat.com>,
Felix Kuehling <Felix.Kuehling@amd.com>,
linux-usb@vger.kernel.org, io-uring@vger.kernel.org,
linux-kernel@vger.kernel.org,
Zhenyu Wang <zhenyuw@linux.intel.com>,
virtualization@lists.linux-foundation.org, linux-mm@kvack.org,
linux-fsdevel@vger.kernel.org, Al Viro <viro@zeniv.linux.org.uk>,
intel-gfx@lists.freedesktop.org,
Alex Deucher <alexander.deucher@amd.com>,
intel-gvt-dev@lists.freedesktop.org,
Jason Wang <jasowang@redhat.com>, Zhi Wang <zhi.a.wang@intel.com>
Subject: Re: [PATCH 2/6] i915/gvt/kvm: a NULL ->mm does not mean a thread is a kthread
Date: Mon, 6 Apr 2020 23:08:46 -0400 [thread overview]
Message-ID: <20200407030845.GA10586@joy-OptiPlex-7040> (raw)
In-Reply-To: <20200404094101.672954-3-hch@lst.de>
On Sat, Apr 04, 2020 at 11:40:57AM +0200, Christoph Hellwig wrote:
> Use the proper API instead.
>
> Fixes: f440c8a572d7 ("drm/i915/gvt/kvmgt: read/write GPA via KVM API")
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> drivers/gpu/drm/i915/gvt/kvmgt.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
> index 074c4efb58eb..5848400620b4 100644
> --- a/drivers/gpu/drm/i915/gvt/kvmgt.c
> +++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
> @@ -2037,7 +2037,7 @@ static int kvmgt_rw_gpa(unsigned long handle, unsigned long gpa,
> struct kvmgt_guest_info *info;
> struct kvm *kvm;
> int idx, ret;
> - bool kthread = current->mm == NULL;
> + bool kthread = (current->flags & PF_KTHREAD);
>
> if (!handle_valid(handle))
> return -ESRCH;
> --
> 2.25.1
>
hi
we were removing this code. see
https://lore.kernel.org/kvm/20200313031109.7989-1-yan.y.zhao@intel.com/
The implementation of vfio_dma_rw() has been in vfio next tree.
https://github.com/awilliam/linux-vfio/commit/8d46c0cca5f4dc0538173d62cd36b1119b5105bc
in vfio_dma_rw(), we still use
bool kthread = current->mm == NULL.
because if current->mm != NULL and current->flags & PF_KTHREAD, instead
of calling use_mm(), we first check if (current->mm == mm) and allow copy_to_user() if it's true.
Do you think it's all right?
Thanks
Yan
> _______________________________________________
> intel-gvt-dev mailing list
> intel-gvt-dev@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gvt-dev
next prev parent reply other threads:[~2020-04-07 3:18 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-04 9:40 improve use_mm / unuse_mm Christoph Hellwig
2020-04-04 9:40 ` [PATCH 1/6] amdgpu: a NULL ->mm does not mean a thread is a kthread Christoph Hellwig
2020-04-06 16:07 ` Felix Kuehling
2020-04-04 9:40 ` [PATCH 2/6] i915/gvt/kvm: " Christoph Hellwig
2020-04-04 10:05 ` Sergei Shtylyov
2020-04-07 3:08 ` Yan Zhao [this message]
2020-04-13 13:27 ` Christoph Hellwig
2020-04-14 0:04 ` Yan Zhao
2020-04-14 7:00 ` Christoph Hellwig
2020-04-14 7:03 ` Yan Zhao
2020-04-04 9:40 ` [PATCH 3/6] i915/gvt: remove unused xen bits Christoph Hellwig
2020-04-08 1:44 ` Zhenyu Wang
2020-04-13 13:08 ` Christoph Hellwig
2020-04-14 3:04 ` Zhenyu Wang
2020-04-04 9:40 ` [PATCH 4/6] kernel: move use_mm/unuse_mm to kthread.c Christoph Hellwig
2020-04-06 16:09 ` Felix Kuehling
2020-04-04 9:41 ` [PATCH 5/6] kernel: better document the use_mm/unuse_mm API contract Christoph Hellwig
2020-04-04 13:07 ` [Intel-gfx] " Pavel Begunkov
2020-04-06 16:10 ` Felix Kuehling
2020-04-04 9:41 ` [PATCH 6/6] kernel: set USER_DS in kthread_use_mm Christoph Hellwig
2020-04-06 21:49 ` Michael S. Tsirkin
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