On Wed, Apr 13, 2022 at 10:59 AM Ben Gardon <bgardon@xxxxxxxxxx> wrote: > > Given the high cost of NX hugepages in terms of TLB performance, it may > be desirable to disable the mitigation on a per-VM basis. In the case of public > cloud providers with many VMs on a single host, some VMs may be more trusted > than others. In order to maximize performance on critical VMs, while still > providing some protection to the host from iTLB Multihit, allow the mitigation > to be selectively disabled. For the series: Reviewed-by: David Matlack <dmatlack@xxxxxxxxxx> > > Disabling NX hugepages on a VM is relatively straightforward, but I took this > as an opportunity to add some NX hugepages test coverage and clean up selftests > infrastructure a bit. > > This series was tested with the new selftest and the rest of the KVM selftests > on an Intel Haswell machine. > > The following tests failed, but I do not believe that has anything to do with > this series: > userspace_io_test > vmx_nested_tsc_scaling_test > vmx_preemption_timer_test > > Changelog: > v1->v2: > Dropped the complicated memslot refactor in favor of Ricardo Koller's > patch with a similar effect. > Incorporated David Dunn's feedback and reviewed by tag: shortened waits > to speed up test. > v2->v3: > Incorporated a suggestion from David on how to build the NX huge pages > test. > Fixed a build breakage identified by David. > Dropped the per-vm nx_huge_pages field in favor of simply checking the > global + per-VM disable override. > Documented the new capability > Separated out the commit to test disabling NX huge pages > Removed permission check when checking if the disable NX capability is > supported. > Added test coverage for the permission check. > v3->v4: > Collected RB's from Jing and David > Modified stat collection to reduce a memory allocation [David] > Incorporated various improvments to the NX test [David] > Changed the NX disable test to run by default [David] > Removed some now unnecessary commits > Dropped the code to dump KVM stats from the binary stats test, and > factor out parts of the existing test to library functions instead. > [David, Jing, Sean] > Dropped the improvement to a debugging log message as it's no longer > relevant to this series. > v4->v5: > Incorporated cleanup suggestions from David and Sean > Added a patch with style fixes for the binary stats test from Sean > Added a restriction that NX huge pages can only be disabled before > vCPUs are created [Sean] > > Ben Gardon (9): > KVM: selftests: Remove dynamic memory allocation for stats header > KVM: selftests: Read binary stats header in lib > KVM: selftests: Read binary stats desc in lib > KVM: selftests: Read binary stat data in lib > KVM: selftests: Add NX huge pages test > KVM: x86: Fix errant brace in KVM capability handling > KVM: x86/MMU: Allow NX huge pages to be disabled on a per-vm basis > KVM: selftests: Factor out calculation of pages needed for a VM > KVM: selftests: Test disabling NX hugepages on a VM > > Sean Christopherson (1): > KVM: selftests: Clean up coding style in binary stats test > > Documentation/virt/kvm/api.rst | 13 + > arch/x86/include/asm/kvm_host.h | 2 + > arch/x86/kvm/mmu.h | 9 +- > arch/x86/kvm/mmu/spte.c | 7 +- > arch/x86/kvm/mmu/spte.h | 3 +- > arch/x86/kvm/mmu/tdp_mmu.c | 3 +- > arch/x86/kvm/x86.c | 25 +- > include/uapi/linux/kvm.h | 1 + > tools/testing/selftests/kvm/Makefile | 10 + > .../selftests/kvm/include/kvm_util_base.h | 13 + > .../selftests/kvm/kvm_binary_stats_test.c | 142 ++++++----- > tools/testing/selftests/kvm/lib/kvm_util.c | 232 ++++++++++++++++-- > .../selftests/kvm/x86_64/nx_huge_pages_test.c | 206 ++++++++++++++++ > .../kvm/x86_64/nx_huge_pages_test.sh | 25 ++ > 14 files changed, 597 insertions(+), 94 deletions(-) > create mode 100644 tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c > create mode 100755 tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.sh > > -- > 2.35.1.1178.g4f1659d476-goog >
