Ben Gardon wrote: > When PAE is in use, the root_hpa will not have a shadow page assoicated > with it. In this case the kernel will crash with a NULL pointer > dereference. Add checks to ensure is_tdp_mmu_root works as intended even > when using PAE.
This seems to work in my amd64 case as well. (https://marc.info/?l=linux-kernel&m=160494962201032&w=2) > Tested: compiles > > Fixes: 02c00b3a2f7e ("kvm: x86/mmu: Allocate and free TDP MMU roots") > Reported-by: Zdenek Kaspar <zkaspa...@gmail.com> > Signed-off-by: Ben Gardon <bgar...@google.com> > --- > arch/x86/kvm/mmu/tdp_mmu.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c > index 27e381c9da6c..13013f4d98ad 100644 > --- a/arch/x86/kvm/mmu/tdp_mmu.c > +++ b/arch/x86/kvm/mmu/tdp_mmu.c > @@ -49,8 +49,18 @@ bool is_tdp_mmu_root(struct kvm *kvm, hpa_t hpa) > { > struct kvm_mmu_page *sp; > > + if (WARN_ON(!VALID_PAGE(hpa))) > + return false; > + > sp = to_shadow_page(hpa); > > + /* > + * If this VM is being run with PAE, the TDP MMU will not be enabled > + * and the root HPA will not have a shadow page associated with it. > + */ > + if (!sp) > + return false; > + > return sp->tdp_mmu_page && sp->root_count; > } > > -- > 2.29.2.222.g5d2a92d10f8-goog > -- Jamie Heilman http://audible.transient.net/~jamie/
