| Message ID | a4183c0f0adfb6d123599dd306062fd193e83f5a.1534934405.git.yi.z.zhang@linux.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Fix kvm misconceives NVDIMM pages as reserved mmio | expand |
> > For device specific memory space, when we move these area of pfn to > memory zone, we will set the page reserved flag at that time, some of > these reserved for device mmio, and some of these are not, such as > NVDIMM pmem. > > Now, we map these dev_dax or fs_dax pages to kvm for DIMM/NVDIMM > backend, since these pages are reserved, the check of > kvm_is_reserved_pfn() misconceives those pages as MMIO. Therefor, we > introduce 2 page map types, MEMORY_DEVICE_FS_DAX/MEMORY_DEVICE_DEV_DAX, > to identify these pages are from NVDIMM pmem and let kvm treat these > as normal pages. > > Without this patch, many operations will be missed due to this > mistreatment to pmem pages, for example, a page may not have chance to > be unpinned for KVM guest(in kvm_release_pfn_clean), not able to be > marked as dirty/accessed(in kvm_set_pfn_dirty/accessed) etc. > > Signed-off-by: Zhang Yi <yi.z.zhang@linux.intel.com> > --- > virt/kvm/kvm_main.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index c44c406..969b6ca 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -147,8 +147,12 @@ __weak void > kvm_arch_mmu_notifier_invalidate_range(struct kvm *kvm, > > bool kvm_is_reserved_pfn(kvm_pfn_t pfn) > { > - if (pfn_valid(pfn)) > - return PageReserved(pfn_to_page(pfn)); > + struct page *page; > + > + if (pfn_valid(pfn)) { > + page = pfn_to_page(pfn); > + return PageReserved(page) && !is_dax_page(page); > + } > > return true; > } Acked-by: Pankaj Gupta <pagupta@redhat.com> > -- > 2.7.4 > >
On 08/22/2018 03:58 AM, Zhang Yi wrote: > bool kvm_is_reserved_pfn(kvm_pfn_t pfn) > { > - if (pfn_valid(pfn)) > - return PageReserved(pfn_to_page(pfn)); > + struct page *page; > + > + if (pfn_valid(pfn)) { > + page = pfn_to_page(pfn); > + return PageReserved(page) && !is_dax_page(page); > + } This is in desperate need of commenting about what it is doing and why. The changelog alone doesn't cut it.
On 2018-08-29 at 06:15:48 -0400, Pankaj Gupta wrote: > > > > > For device specific memory space, when we move these area of pfn to > > memory zone, we will set the page reserved flag at that time, some of > > these reserved for device mmio, and some of these are not, such as > > NVDIMM pmem. > > > > Now, we map these dev_dax or fs_dax pages to kvm for DIMM/NVDIMM > > backend, since these pages are reserved, the check of > > kvm_is_reserved_pfn() misconceives those pages as MMIO. Therefor, we > > introduce 2 page map types, MEMORY_DEVICE_FS_DAX/MEMORY_DEVICE_DEV_DAX, > > to identify these pages are from NVDIMM pmem and let kvm treat these > > as normal pages. > > > > Without this patch, many operations will be missed due to this > > mistreatment to pmem pages, for example, a page may not have chance to > > be unpinned for KVM guest(in kvm_release_pfn_clean), not able to be > > marked as dirty/accessed(in kvm_set_pfn_dirty/accessed) etc. > > > > Signed-off-by: Zhang Yi <yi.z.zhang@linux.intel.com> > > --- > > virt/kvm/kvm_main.c | 8 ++++++-- > > 1 file changed, 6 insertions(+), 2 deletions(-) > > > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > > index c44c406..969b6ca 100644 > > --- a/virt/kvm/kvm_main.c > > +++ b/virt/kvm/kvm_main.c > > @@ -147,8 +147,12 @@ __weak void > > kvm_arch_mmu_notifier_invalidate_range(struct kvm *kvm, > > > > bool kvm_is_reserved_pfn(kvm_pfn_t pfn) > > { > > - if (pfn_valid(pfn)) > > - return PageReserved(pfn_to_page(pfn)); > > + struct page *page; > > + > > + if (pfn_valid(pfn)) { > > + page = pfn_to_page(pfn); > > + return PageReserved(page) && !is_dax_page(page); > > + } > > > > return true; > > } > > Acked-by: Pankaj Gupta <pagupta@redhat.com> Thanks for your kindly review, Pankaj, as all the patch [1,2,3,4]/4 got the reviewed[acked]-by, can we Queue this by now? > > > -- > > 2.7.4 > > > >
On 2018-08-30 at 12:07:11 -0700, Dave Hansen wrote: > On 08/22/2018 03:58 AM, Zhang Yi wrote: > > bool kvm_is_reserved_pfn(kvm_pfn_t pfn) > > { > > - if (pfn_valid(pfn)) > > - return PageReserved(pfn_to_page(pfn)); > > + struct page *page; > > + > > + if (pfn_valid(pfn)) { > > + page = pfn_to_page(pfn); > > + return PageReserved(page) && !is_dax_page(page); > > + } > > This is in desperate need of commenting about what it is doing and why. > > The changelog alone doesn't cut it. Thanks, Dave, Will add some comments
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index c44c406..969b6ca 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -147,8 +147,12 @@ __weak void kvm_arch_mmu_notifier_invalidate_range(struct kvm *kvm, bool kvm_is_reserved_pfn(kvm_pfn_t pfn) { - if (pfn_valid(pfn)) - return PageReserved(pfn_to_page(pfn)); + struct page *page; + + if (pfn_valid(pfn)) { + page = pfn_to_page(pfn); + return PageReserved(page) && !is_dax_page(page); + } return true; }
For device specific memory space, when we move these area of pfn to memory zone, we will set the page reserved flag at that time, some of these reserved for device mmio, and some of these are not, such as NVDIMM pmem. Now, we map these dev_dax or fs_dax pages to kvm for DIMM/NVDIMM backend, since these pages are reserved, the check of kvm_is_reserved_pfn() misconceives those pages as MMIO. Therefor, we introduce 2 page map types, MEMORY_DEVICE_FS_DAX/MEMORY_DEVICE_DEV_DAX, to identify these pages are from NVDIMM pmem and let kvm treat these as normal pages. Without this patch, many operations will be missed due to this mistreatment to pmem pages, for example, a page may not have chance to be unpinned for KVM guest(in kvm_release_pfn_clean), not able to be marked as dirty/accessed(in kvm_set_pfn_dirty/accessed) etc. Signed-off-by: Zhang Yi <yi.z.zhang@linux.intel.com> --- virt/kvm/kvm_main.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)