On Tue, Oct 09, 2018 at 12:38:41PM +0100, Paul Durrant wrote: > > -----Original Message----- > > From: Xen-devel [mailto:xen-devel-boun...@lists.xenproject.org] On Behalf > > Of Paul Durrant > > Sent: 09 October 2018 12:23 > > To: Wei Liu <wei.l...@citrix.com>; xen-devel@lists.xenproject.org > > Cc: Kevin Tian <kevin.t...@intel.com>; Wei Liu <wei.l...@citrix.com>; Jan > > Beulich <jbeul...@suse.com>; Roger Pau Monne <roger....@citrix.com> > > Subject: Re: [Xen-devel] [PATCH] x86/vtd: fix IOMMU share PT destruction > > path > > > > > -----Original Message----- > > > From: Wei Liu [mailto:wei.l...@citrix.com] > > > Sent: 09 October 2018 11:42 > > > To: xen-devel@lists.xenproject.org > > > Cc: Jan Beulich <jbeul...@suse.com>; Roger Pau Monne > > > <roger....@citrix.com>; Paul Durrant <paul.durr...@citrix.com>; Wei Liu > > > <wei.l...@citrix.com>; Kevin Tian <kevin.t...@intel.com> > > > Subject: [PATCH] x86/vtd: fix IOMMU share PT destruction path > > > > > > Commit 2916951c1 ("mm / iommu: include need_iommu() test in > > > iommu_use_hap_pt()") included need_iommu() in iommu_use_hap_pt and > > > 91d4eca7add (" mm / iommu: split need_iommu() into has_iommu_pt() and > > > need_iommu_pt_sync()") made things finer grain by spliting need_iommu > > > into three states. > > > > > > The destruction path can't use iommu_use_hap_pt because at the point > > > platform op is called, IOMMU is already switched to disabled state and > > > the shared PT test would always be false. > > > > > > > This is VT-d specific and the issue could affect AMD too. > > Yes, it looks like deallocate_iommu_page_tables() will then try to deallocate > page tables that would not have been allocated. This probably happens to be > safe because the root table is allocated on demand, but that might change in > future so I think it better to fix as I suggest below. > > Paul > > > Can't you just > > switch round the call to teardown and setting IOMMU_status_disabled in > > xen/drivers/passthrough/iommu.c:iommu_teardown()?
OK. I will swap those lines instead. Wei. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel