Hello, IIUC this is the first independent patch series for guest_memfd's in-place conversion series! Happy to finally bring this out on its own.
Previous versions of this feature, part of other series, are available at [1][2][3]. Many prior discussions have led up to these main features of this series, and these are the main points I'd like feedback on. 1. Having private/shared status stored in a maple tree (Thanks Michael for your support of using maple trees over xarrays for performance! [4]). 2. Having a new guest_memfd ioctl (not a vm ioctl) that performs conversions. 3. Using ioctls/structs/input attribute similar to the existing vm ioctl KVM_SET_MEMORY_ATTRIBUTES to perform conversions. 4. Storing requested attributes directly in the maple tree. 5. Using a KVM module-wide param to toggle between setting memory attributes via vm and guest_memfd ioctls (making them mututally exclusive - a single loaded KVM module can only do one of the two.) 6. Skipping LRU in guest_memfd folios - make guest_memfd folios not participate in LRU to avoid LRU refcounts from interfering with conversions. This series is based on kvm/next, followed by + v12 of NUMA mempolicy support patches [5] + 3 cleanup patches from Sean [6][7][8] Everything is stitched together here for your convenience https://github.com/googleprodkernel/linux-cc/commits/guest_memfd-inplace-conversion-v1 Thank you all for helping with this series! If I missed out your comment from a previous series, it's not intentional! Please do raise it again. TODOs: + There might be an issue with memory failure handling because when guest_memfd folios stop participating in LRU. From a preliminary analysis, HWPoisonHandlable() is only true if PageLRU() is true. This needs further investigation. [1] https://lore.kernel.org/all/bd163de3118b626d1005aa88e71ef2fb72f0be0f.1726009989.git.ackerley...@google.com/ [2] https://lore.kernel.org/all/[email protected]/ [3] https://lore.kernel.org/all/b784326e9ccae6a08388f1bf39db70a2204bdc51.1747264138.git.ackerley...@google.com/ [4] https://lore.kernel.org/all/[email protected]/ [5] https://lore.kernel.org/all/[email protected]/T/ [6] https://lore.kernel.org/all/[email protected]/ [7] https://lore.kernel.org/all/[email protected]/ [8] https://lore.kernel.org/all/[email protected]/ Ackerley Tng (19): KVM: guest_memfd: Update kvm_gmem_populate() to use gmem attributes KVM: Introduce KVM_SET_MEMORY_ATTRIBUTES2 KVM: guest_memfd: Don't set FGP_ACCESSED when getting folios KVM: guest_memfd: Skip LRU for guest_memfd folios KVM: guest_memfd: Add support for KVM_SET_MEMORY_ATTRIBUTES KVM: selftests: Update framework to use KVM_SET_MEMORY_ATTRIBUTES2 KVM: selftests: guest_memfd: Test basic single-page conversion flow KVM: selftests: guest_memfd: Test conversion flow when INIT_SHARED KVM: selftests: guest_memfd: Test indexing in guest_memfd KVM: selftests: guest_memfd: Test conversion before allocation KVM: selftests: guest_memfd: Convert with allocated folios in different layouts KVM: selftests: guest_memfd: Test precision of conversion KVM: selftests: guest_memfd: Test that truncation does not change shared/private status KVM: selftests: guest_memfd: Test conversion with elevated page refcount KVM: selftests: Reset shared memory after hole-punching KVM: selftests: Provide function to look up guest_memfd details from gpa KVM: selftests: Make TEST_EXPECT_SIGBUS thread-safe KVM: selftests: Update private_mem_conversions_test to mmap() guest_memfd KVM: selftests: Add script to exercise private_mem_conversions_test Sean Christopherson (18): KVM: guest_memfd: Introduce per-gmem attributes, use to guard user mappings KVM: Rename KVM_GENERIC_MEMORY_ATTRIBUTES to KVM_VM_MEMORY_ATTRIBUTES KVM: Enumerate support for PRIVATE memory iff kvm_arch_has_private_mem is defined KVM: Stub in ability to disable per-VM memory attribute tracking KVM: guest_memfd: Wire up kvm_get_memory_attributes() to per-gmem attributes KVM: guest_memfd: Enable INIT_SHARED on guest_memfd for x86 Coco VMs KVM: Move KVM_VM_MEMORY_ATTRIBUTES config definition to x86 KVM: Let userspace disable per-VM mem attributes, enable per-gmem attributes KVM: selftests: Create gmem fd before "regular" fd when adding memslot KVM: selftests: Rename guest_memfd{,_offset} to gmem_{fd,offset} KVM: selftests: Add support for mmap() on guest_memfd in core library KVM: selftests: Add helpers for calling ioctls on guest_memfd KVM: selftests: guest_memfd: Test that shared/private status is consistent across processes KVM: selftests: Add selftests global for guest memory attributes capability KVM: selftests: Provide common function to set memory attributes KVM: selftests: Check fd/flags provided to mmap() when setting up memslot KVM: selftests: Update pre-fault test to work with per-guest_memfd attributes KVM: selftests: Update private memory exits test work with per-gmem attributes Documentation/virt/kvm/api.rst | 72 ++- arch/x86/include/asm/kvm_host.h | 2 +- arch/x86/kvm/Kconfig | 15 +- arch/x86/kvm/mmu/mmu.c | 4 +- arch/x86/kvm/x86.c | 13 +- include/linux/kvm_host.h | 44 +- include/trace/events/kvm.h | 4 +- include/uapi/linux/kvm.h | 17 + mm/filemap.c | 1 + mm/memcontrol.c | 2 + tools/testing/selftests/kvm/.gitignore | 1 + tools/testing/selftests/kvm/Makefile.kvm | 1 + .../kvm/guest_memfd_conversions_test.c | 498 ++++++++++++++++++ .../testing/selftests/kvm/include/kvm_util.h | 127 ++++- .../testing/selftests/kvm/include/test_util.h | 29 +- tools/testing/selftests/kvm/lib/kvm_util.c | 128 +++-- tools/testing/selftests/kvm/lib/test_util.c | 7 - .../selftests/kvm/pre_fault_memory_test.c | 2 +- .../kvm/x86/private_mem_conversions_test.c | 55 +- .../kvm/x86/private_mem_conversions_test.py | 159 ++++++ .../kvm/x86/private_mem_kvm_exits_test.c | 36 +- virt/kvm/Kconfig | 4 +- virt/kvm/guest_memfd.c | 414 +++++++++++++-- virt/kvm/kvm_main.c | 104 +++- 24 files changed, 1554 insertions(+), 185 deletions(-) create mode 100644 tools/testing/selftests/kvm/guest_memfd_conversions_test.c create mode 100755 tools/testing/selftests/kvm/x86/private_mem_conversions_test.py -- 2.51.0.858.gf9c4a03a3a-goog
