On Thu, Oct 24, 2019 at 5:10 AM David Hildenbrand <[email protected]> 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 kvm_is_mmio_pfn() to make sure the function produces the > same result once we stop setting ZONE_DEVICE pages PG_reserved. > > Cc: Paolo Bonzini <[email protected]> > Cc: "Radim Krčmář" <[email protected]> > Cc: Sean Christopherson <[email protected]> > Cc: Vitaly Kuznetsov <[email protected]> > Cc: Wanpeng Li <[email protected]> > Cc: Jim Mattson <[email protected]> > Cc: Joerg Roedel <[email protected]> > Cc: Thomas Gleixner <[email protected]> > Cc: Ingo Molnar <[email protected]> > Cc: Borislav Petkov <[email protected]> > Cc: "H. Peter Anvin" <[email protected]> > Cc: KarimAllah Ahmed <[email protected]> > Cc: Michal Hocko <[email protected]> > Cc: Dan Williams <[email protected]> > Signed-off-by: David Hildenbrand <[email protected]> > --- > arch/x86/kvm/mmu.c | 29 +++++++++++++++++------------ > 1 file changed, 17 insertions(+), 12 deletions(-) > > diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c > index 24c23c66b226..f03089a336de 100644 > --- a/arch/x86/kvm/mmu.c > +++ b/arch/x86/kvm/mmu.c > @@ -2962,20 +2962,25 @@ static bool mmu_need_write_protect(struct kvm_vcpu > *vcpu, gfn_t gfn, > > static bool kvm_is_mmio_pfn(kvm_pfn_t pfn) > { > + struct page *page = pfn_to_online_page(pfn); > + > + /* > + * ZONE_DEVICE pages are never online. Online pages that are reserved > + * either indicate the zero page or MMIO pages. > + */ > + if (page) > + return !is_zero_pfn(pfn) && PageReserved(pfn_to_page(pfn)); > + > + /* > + * Anything with a valid (but not online) memmap could be ZONE_DEVICE. > + * Treat only UC/UC-/WC pages as MMIO.
You might clarify that ZONE_DEVICE pages that belong to WB cacheable pmem have the correct memtype established by devm_memremap_pages(). Other than that, feel free to add: Reviewed-by: Dan Williams <[email protected]> _______________________________________________ devel mailing list [email protected] http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
