On Fri, Mar 19, 2021 at 10:01:37AM +0000, Quentin Perret wrote: > As the host stage 2 will be identity mapped, all the .hyp memory regions > and/or memory pages donated to protected guestis will have to marked > invalid in the host stage 2 page-table. At the same time, the hypervisor > will need a way to track the ownership of each physical page to ensure > memory sharing or donation between entities (host, guests, hypervisor) is > legal. > > In order to enable this tracking at EL2, let's use the host stage 2 > page-table itself. The idea is to use the top bits of invalid mappings > to store the unique identifier of the page owner. The page-table owner > (the host) gets identifier 0 such that, at boot time, it owns the entire > IPA space as the pgd starts zeroed. > > Provide kvm_pgtable_stage2_set_owner() which allows to modify the > ownership of pages in the host stage 2. It re-uses most of the map() > logic, but ends up creating invalid mappings instead. This impacts > how we do refcount as we now need to count invalid mappings when they > are used for ownership tracking. > > Signed-off-by: Quentin Perret <qperret@xxxxxxxxxx> > --- > arch/arm64/include/asm/kvm_pgtable.h | 20 +++++ > arch/arm64/kvm/hyp/pgtable.c | 126 ++++++++++++++++++++++----- > 2 files changed, 122 insertions(+), 24 deletions(-) Acked-by: Will Deacon <will@xxxxxxxxxx> Will _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
