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Peter Anvin" , Ingo Molnar , "Isaac J. Manjarres" , Jim Mattson , Joerg Roedel , Johannes Weiner , Juergen Gross , KarimAllah Ahmed , Kees Cook , "K. Y. Srinivasan" , "Matthew Wilcox (Oracle)" , Matt Sickler , Mel Gorman , Michael Ellerman , Michal Hocko , Mike Rapoport , Mike Rapoport , Nicholas Piggin , Oscar Salvador , Paolo Bonzini , Paul Mackerras , Paul Mackerras , Pavel Tatashin , Pavel Tatashin , Peter Zijlstra , Qian Cai , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Sasha Levin , Sean Christopherson , Stefano Stabellini , Stephen Hemminger , Thomas Gleixner , Vitaly Kuznetsov , Vlastimil Babka , Wanpeng Li , YueHaibing Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Oct 24, 2019 at 5:12 AM David Hildenbrand wrote: > > Right now, ZONE_DEVICE memory is always set PG_reserved. We want to > change that. > > KVM has this weird use case that you can map anything from /dev/mem > into the guest. pfn_valid() is not a reliable check whether the memmap > was initialized and can be touched. pfn_to_online_page() makes sure > that we have an initialized memmap (and don't have ZONE_DEVICE memory). > > Rewrite is_invalid_reserved_pfn() similar to kvm_is_reserved_pfn() to make > sure the function produces the same result once we stop setting ZONE_DEVICE > pages PG_reserved. > > Cc: Alex Williamson > Cc: Cornelia Huck > Signed-off-by: David Hildenbrand > --- > drivers/vfio/vfio_iommu_type1.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c > index 2ada8e6cdb88..f8ce8c408ba8 100644 > --- a/drivers/vfio/vfio_iommu_type1.c > +++ b/drivers/vfio/vfio_iommu_type1.c > @@ -299,9 +299,15 @@ static int vfio_lock_acct(struct vfio_dma *dma, long npage, bool async) > */ > static bool is_invalid_reserved_pfn(unsigned long pfn) > { > - if (pfn_valid(pfn)) > - return PageReserved(pfn_to_page(pfn)); > + struct page *page = pfn_to_online_page(pfn); Ugh, I just realized this is not a safe conversion until pfn_to_online_page() is moved over to subsection granularity. As it stands it will return true for any ZONE_DEVICE pages that share a section with boot memory.