This mini-series fixes a suspected, but technically unconfirmed, bug in KVM related to ZONE_DEVICE pages. The suspected issue is that KVM treats ZONE_DEVICE pages as reserved PFNs, and so doesn't put references to such pages when dropping references via KVM's generic kvm_release_pfn_clean(). David Hildenbrand uncovered the bug during a discussion about removing PG_reserved from ZONE_DEVICE pages, after Dan Williams pointed out[1] that there was a bug report from Adam Borowski[2] that was likely related to KVM's interaction with PageReserved(). Patch 1/2 contains the actual fix, patch 2/2 is a minor cleanup that is mostly unrelated, but dependent and prompted by the fix in patch 1/2. The fix itself is a bit more aggressive than what was proposed by David and Dan, but I'm fairly confident it's the right direction for the long term, and it also plays nice with the original PG_reserved removal series that exposed the bug. To be 100% clear, I haven't actually confirmed this fixes the bug reported by Adam. [1] http://lkml.kernel.org/r/20190919115547.GA17963@xxxxxxxxxx [2] https://lkml.kernel.org/r/01adb4cb-6092-638c-0bab-e61322be7cf5@xxxxxxxxxx Sean Christopherson (2): KVM: MMU: Do not treat ZONE_DEVICE pages as being reserved KVM: x86/mmu: Add helper to consolidate huge page promotion arch/x86/kvm/mmu.c | 15 +++++++++------ include/linux/kvm_host.h | 1 + virt/kvm/kvm_main.c | 19 +++++++++++++++---- 3 files changed, 25 insertions(+), 10 deletions(-) -- 2.24.0
