| Message ID | 20190404202345.133553-1-brho@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
-yi.z.zhang@intel.com (Bad email address / failure) Sorry about that. On 4/4/19 4:23 PM, Barret Rhoden wrote: > This patch series depends on DAX pages not being PageReserved. Once > that is in place, these changes will let KVM use huge pages with > DAX-backed files. > > From previous discussions[1], it sounds like DAX might not need to keep > the PageReserved bit, but that it hadn't been sorted out yet. > > Without the PageReserved change, KVM and DAX still work with these > patches, simply without huge pages - which is the current situation. > > If you want to test the huge-page functionality as if DAX pages weren't > PageReserved for KVM, this hack does the trick: > > ------------------ > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index c44985375e7f..ee539eec1fb8 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -153,6 +153,10 @@ __weak int kvm_arch_mmu_notifier_invalidate_range(struct kvm *kvm, > > bool kvm_is_reserved_pfn(kvm_pfn_t pfn) > { > + // XXX hack > + if (is_zone_device_page(pfn_to_page(pfn))) > + return false; > + > if (pfn_valid(pfn)) > return PageReserved(pfn_to_page(pfn)); > > ------------------ > > Perhaps if we are going to leave DAX pages marked PageReserved, then I > can make that hack into a proper commit and have KVM alone treat DAX > pages as if they are not reserved. > > v2 -> v3: > v2: https://lore.kernel.org/lkml/20181114215155.259978-1-brho@google.com/ > - Updated Acks/Reviewed-by > - Rebased onto linux-next > > v1 -> v2: > https://lore.kernel.org/lkml/20181109203921.178363-1-brho@google.com/ > - Updated Acks/Reviewed-by > - Minor touchups > - Added patch to remove redundant PageReserved() check > - Rebased onto linux-next > > RFC/discussion thread: > https://lore.kernel.org/lkml/20181029210716.212159-1-brho@google.com/ > > [1] https://lore.kernel.org/lkml/ee8cc068-903c-d87e-f418-ade46786249e@redhat.com/ > > Barret Rhoden (3): > mm: make dev_pagemap_mapping_shift() externally visible > kvm: Use huge pages for DAX-backed files > kvm: remove redundant PageReserved() check > > arch/x86/kvm/mmu.c | 33 +++++++++++++++++++++++++++++++-- > include/linux/mm.h | 3 +++ > mm/memory-failure.c | 38 +++----------------------------------- > mm/util.c | 34 ++++++++++++++++++++++++++++++++++ > virt/kvm/kvm_main.c | 8 ++------ > 5 files changed, 73 insertions(+), 43 deletions(-) >
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index c44985375e7f..ee539eec1fb8 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -153,6 +153,10 @@ __weak int kvm_arch_mmu_notifier_invalidate_range(struct kvm *kvm, bool kvm_is_reserved_pfn(kvm_pfn_t pfn) { + // XXX hack + if (is_zone_device_page(pfn_to_page(pfn))) + return false; + if (pfn_valid(pfn)) return PageReserved(pfn_to_page(pfn));