| Message ID | 20211104002531.1176691-1-seanjc@google.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | KVM: Scalable memslots implementation | expand |
On 04.11.2021 01:25, Sean Christopherson wrote: > This series is an iteration of Maciej's scalable memslots work. It > addresses most, but not all, of my feedback from v5, hence the "5.5" > moniker. Specifically, I did not touch the iteration over gfn and hva > ranges as I would likely do more harm than good, especially in the gfn > iterator. > > The core functionality of the series is unchanged from v5 (or at least, > it should be). Patches "Resolve memslot ID via a hash table" and "Keep > memslots in tree-based structures" are heavily reworked (the latter in > particular) to provide better continuity between patches and to avoid > the swap() logic when working with the "inactive" set of memslots. But > again, the changes are intended to be purely cosmetic. > > Paolo, ideally I'd like get to patch 03 (and therefore patch 02) into 5.16. > The patch technically breaks backwards compatibility with 32-bit KVM, but > I'm quite confident none of the existing 32-bit architectures can possibly > work. RISC-V is the one exception where it's not obvious that creating > more guest memslot pages than can fit in an unsigned long won't fall on its > face. Since RISC-V is new in 5.16, I'd like to get that change in before > RISC-V can gain any users doing bizarre things. > > s390 folks, please look closely at patch 11, "KVM: s390: Use "new" memslot > instead of userspace memory region". There's a subtle/weird functional > change in there that I can't imagine would negatively affect userspace, > but the end result is odd nonetheless. > > Claudio, I dropped your R-b from "KVM: Integrate gfn_to_memslot_approx() > into search_memslots()" because I changed the code enough to break the s390 > build at least once :-) > > Patches 01 and 02 are bug fixes. > > Patch 03 is fix of sorts to require that the total number of pages across > all memslots fit in an unsigned long. The existing 32-bit KVM > architectures don't correctly handle this case, and fixing those issues > would quite gross and a waste of time. > > Patches 04-18 are cleanups throughout common KVM and all architectures > to fix some warts in the memslot APIs that allow for a cleaner (IMO) > of the tree-based memslots code. They also prep for more improvements > that are realized in the final patch. > > Patches 19-28 are the core of Maciej's scalable memslots work. > > Patches 29-30 take advantage of the tree-based memslots to avoid creating > a dummy "new" memslot on the stack, which simplifies the MOVE case and > aligns it with the other three memslot update cases. Thanks for the updated series Sean - that's an impressive amount of cleanups for the existing KVM code. I've reviewed the non-arch-specific and x86-specific patches till patch 22 (inclusive). Further patches are more invasive and require a more through review - will try to do this in coming days. The arch-specific but non-x86-ones patches look OK to me, too, at the first glance but here it would be better if maintainers or reviewers from particular arch gave their acks. By the way, do you want your patches and my non-invasive patches (patches below number 23) merged without waiting for the rest of the series to be fully ready? This way there is less risk of conflicting changes to KVM being merged in meantime while we are still discussing the remaining patches. Or worse - changes that don't conflict but subtly break some assumptions that the code relies on. For this reason I am strongly for merging them independently from the more invasive parts. Thanks, Maciej
On Tue, Nov 09, 2021, Maciej S. Szmigiero wrote: > On 04.11.2021 01:25, Sean Christopherson wrote: > By the way, do you want your patches and my non-invasive patches (patches > below number 23) merged without waiting for the rest of the series to be > fully ready? > > This way there is less risk of conflicting changes to KVM being merged > in meantime while we are still discussing the remaining patches. > Or worse - changes that don't conflict but subtly break some assumptions > that the code relies on. > > For this reason I am strongly for merging them independently from the > more invasive parts. Merging them as soon as they're ready would also be my preference. That said, I'm hoping we can get the entire implemenation queued up for 5.17 sooner than later. I'll do my best to respond quickly to try and make that happen.
On 09.11.2021 02:21, Sean Christopherson wrote: > On Tue, Nov 09, 2021, Maciej S. Szmigiero wrote: >> On 04.11.2021 01:25, Sean Christopherson wrote: >> By the way, do you want your patches and my non-invasive patches (patches >> below number 23) merged without waiting for the rest of the series to be >> fully ready? >> >> This way there is less risk of conflicting changes to KVM being merged >> in meantime while we are still discussing the remaining patches. >> Or worse - changes that don't conflict but subtly break some assumptions >> that the code relies on. >> >> For this reason I am strongly for merging them independently from the >> more invasive parts. > > Merging them as soon as they're ready would also be my preference. That said, > I'm hoping we can get the entire implemenation queued up for 5.17 sooner than > later. I'll do my best to respond quickly to try and make that happen. > Finished going through all the patches, with small nits they do make sense to me - thanks Sean. I will prepare an updated (and tested!) next version of this patch set, however this may take about two+ weeks as I have other, more urgent work to do right now. Thanks, Maciej
Paolo, I see that you have merged the whole series to kvm/queue, even though it still needed some changes and, most importantly, a good round of testing. Does this mean you want all these changes as a separate patch set on top of the already-merged series? Thanks, Maciej
On 11/23/21 15:42, Maciej S. Szmigiero wrote: > Paolo, > > I see that you have merged the whole series to kvm/queue, even though it > still needed some changes and, most importantly, a good round of testing. > > Does this mean you want all these changes as a separate patch set on top > of the already-merged series? Hi Maciej, you can squash your changes and post a v6. Paolo
This series is an iteration of Maciej's scalable memslots work. It addresses most, but not all, of my feedback from v5, hence the "5.5" moniker. Specifically, I did not touch the iteration over gfn and hva ranges as I would likely do more harm than good, especially in the gfn iterator. The core functionality of the series is unchanged from v5 (or at least, it should be). Patches "Resolve memslot ID via a hash table" and "Keep memslots in tree-based structures" are heavily reworked (the latter in particular) to provide better continuity between patches and to avoid the swap() logic when working with the "inactive" set of memslots. But again, the changes are intended to be purely cosmetic. Paolo, ideally I'd like get to patch 03 (and therefore patch 02) into 5.16. The patch technically breaks backwards compatibility with 32-bit KVM, but I'm quite confident none of the existing 32-bit architectures can possibly work. RISC-V is the one exception where it's not obvious that creating more guest memslot pages than can fit in an unsigned long won't fall on its face. Since RISC-V is new in 5.16, I'd like to get that change in before RISC-V can gain any users doing bizarre things. s390 folks, please look closely at patch 11, "KVM: s390: Use "new" memslot instead of userspace memory region". There's a subtle/weird functional change in there that I can't imagine would negatively affect userspace, but the end result is odd nonetheless. Claudio, I dropped your R-b from "KVM: Integrate gfn_to_memslot_approx() into search_memslots()" because I changed the code enough to break the s390 build at least once :-) Patches 01 and 02 are bug fixes. Patch 03 is fix of sorts to require that the total number of pages across all memslots fit in an unsigned long. The existing 32-bit KVM architectures don't correctly handle this case, and fixing those issues would quite gross and a waste of time. Patches 04-18 are cleanups throughout common KVM and all architectures to fix some warts in the memslot APIs that allow for a cleaner (IMO) of the tree-based memslots code. They also prep for more improvements that are realized in the final patch. Patches 19-28 are the core of Maciej's scalable memslots work. Patches 29-30 take advantage of the tree-based memslots to avoid creating a dummy "new" memslot on the stack, which simplifies the MOVE case and aligns it with the other three memslot update cases. v5.5 * Add all the pre- and post-work cleanups. * Rebase to kvm/queue, commit 0d7d84498fb4 ("KVM: x86: SGX must...") * Name innermost helper ____gfn_to_memslot() instead of ...approx. [Sean] * Rework hash list patch and all subsequent tree modifications to use common kvm_memslot_replace() helper. [Sean] * Rework tree-based approach to avoid swap() by always pulling the invalid memslot tree on-demand, and by relying on precise variables names and comments (for the invidual memslot pointers). v5: * https://lkml.kernel.org/r/cover.1632171478.git.maciej.szmigiero@oracle.com * Rebase onto v5.15-rc2 (torvalds/master), * Fix 64-bit division of n_memslots_pages for 32-bit KVM, * Collect Claudio's Reviewed-by tags for some of the patches. Early history can be found in the above lore link. Maciej S. Szmigiero (10): KVM: Resync only arch fields when slots_arch_lock gets reacquired KVM: x86: Use nr_memslot_pages to avoid traversing the memslots array KVM: Integrate gfn_to_memslot_approx() into search_memslots() KVM: Move WARN on invalid memslot index to update_memslots() KVM: Resolve memslot ID via a hash table instead of via a static array KVM: Use interval tree to do fast hva lookup in memslots KVM: s390: Introduce kvm_s390_get_gfn_end() KVM: Keep memslots in tree-based structures instead of array-based ones KVM: Optimize gfn lookup in kvm_zap_gfn_range() KVM: Optimize overlapping memslots check Sean Christopherson (20): KVM: Ensure local memslot copies operate on up-to-date arch-specific data KVM: Disallow user memslot with size that exceeds "unsigned long" KVM: Require total number of memslot pages to fit in an unsigned long KVM: Open code kvm_delete_memslot() into its only caller KVM: Use "new" memslot's address space ID instead of dedicated param KVM: Let/force architectures to deal with arch specific memslot data KVM: arm64: Use "new" memslot instead of userspace memory region KVM: MIPS: Drop pr_debug from memslot commit to avoid using "mem" KVM: PPC: Avoid referencing userspace memory region in memslot updates KVM: s390: Use "new" memslot instead of userspace memory region KVM: x86: Use "new" memslot instead of userspace memory region KVM: RISC-V: Use "new" memslot instead of userspace memory region KVM: Stop passing kvm_userspace_memory_region to arch memslot hooks KVM: Use prepare/commit hooks to handle generic memslot metadata updates KVM: x86: Don't assume old/new memslots are non-NULL at memslot commit KVM: s390: Skip gfn/size sanity checks on memslot DELETE or FLAGS_ONLY KVM: Don't make a full copy of the old memslot in __kvm_set_memory_region() KVM: x86: Don't call kvm_mmu_change_mmu_pages() if the count hasn't changed KVM: Wait 'til the bitter end to initialize the "new" memslot KVM: Dynamically allocate "new" memslots from the get-go arch/arm64/kvm/Kconfig | 1 + arch/arm64/kvm/mmu.c | 27 +- arch/mips/kvm/Kconfig | 1 + arch/mips/kvm/mips.c | 9 +- arch/powerpc/include/asm/kvm_ppc.h | 18 +- arch/powerpc/kvm/Kconfig | 1 + arch/powerpc/kvm/book3s.c | 14 +- arch/powerpc/kvm/book3s_64_mmu_hv.c | 4 +- arch/powerpc/kvm/book3s_hv.c | 28 +- arch/powerpc/kvm/book3s_hv_nested.c | 4 +- arch/powerpc/kvm/book3s_hv_uvmem.c | 14 +- arch/powerpc/kvm/book3s_pr.c | 17 +- arch/powerpc/kvm/booke.c | 7 +- arch/powerpc/kvm/powerpc.c | 9 +- arch/riscv/kvm/mmu.c | 34 +- arch/s390/kvm/Kconfig | 1 + arch/s390/kvm/kvm-s390.c | 98 ++-- arch/s390/kvm/kvm-s390.h | 14 + arch/s390/kvm/pv.c | 4 +- arch/x86/include/asm/kvm_host.h | 1 - arch/x86/kvm/Kconfig | 1 + arch/x86/kvm/debugfs.c | 6 +- arch/x86/kvm/mmu/mmu.c | 39 +- arch/x86/kvm/x86.c | 42 +- include/linux/kvm_host.h | 240 +++++--- virt/kvm/kvm_main.c | 868 ++++++++++++++++------------ 26 files changed, 855 insertions(+), 647 deletions(-)