Re: [PATCH 13/13] vfio/type1: Mark follow_pfn as unsafe

2020-10-08 Thread Jason Gunthorpe
On Wed, Oct 07, 2020 at 08:14:06PM +0200, Daniel Vetter wrote: > Hm, but wouldn't need that the semi-nasty vma_open trick to make sure > that vma doesn't untimely disappear? Or is the idea to look up the > underlying vfio object, and refcount that directly? Ah, the patches Alex was working on

Re: [PATCH 13/13] vfio/type1: Mark follow_pfn as unsafe

2020-10-08 Thread Jason Gunthorpe
On Wed, Oct 07, 2020 at 06:44:26PM +0200, Daniel Vetter wrote: > The code seems to stuff these pfns into iommu pts (or something like > that, I didn't follow), but there's no mmu_notifier to ensure that > access is synchronized with pte updates. > > Hence mark these as unsafe. This means that

Re: [PATCH 13/13] vfio/type1: Mark follow_pfn as unsafe

2020-10-07 Thread Daniel Vetter
On Wed, Oct 7, 2020 at 7:39 PM Jason Gunthorpe wrote: > > On Wed, Oct 07, 2020 at 06:44:26PM +0200, Daniel Vetter wrote: > > The code seems to stuff these pfns into iommu pts (or something like > > that, I didn't follow), but there's no mmu_notifier to ensure that > > access is synchronized with

[PATCH 13/13] vfio/type1: Mark follow_pfn as unsafe

2020-10-07 Thread Daniel Vetter
The code seems to stuff these pfns into iommu pts (or something like that, I didn't follow), but there's no mmu_notifier to ensure that access is synchronized with pte updates. Hence mark these as unsafe. This means that with CONFIG_STRICT_FOLLOW_PFN, these will be rejected. Real fix is to wire