Message-ID: <20230210003148.2646712-1-seanjc@google.com>
Date:   Fri, 10 Feb 2023 00:31:27 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Xiaoyao Li <xiaoyao.li@...el.com>,
        Like Xu <like.xu.linux@...il.com>
Subject: [PATCH v2 00/21] KVM: x86: Disallow writes to feature MSRs post-KVM_RUN

Give feature MSRs that same treatment as CPUID and disallow changing said
MSRs after KVM_RUN.  Fix a tangentially related bug in the vPMU where KVM
leaves the vLBRs enabled after userspace disables the guest's entire vPMU.

The bulk of this series is a rework of the vmx_pmu_caps_test, a.k.a.
the PERF_CAPABILITIES selftests, to expand its coverage.  In addition to
verifying that KVM rejects changes after KVM_RUN, verify other bits beyond
full-width writes and the LBR format.

Note!  There is a sneaky, small, but massive change buried halfway through
this series that will affect all x86 selftests.  Patch

  Verify KVM preserves userspace writes to "durable" MSRs

adds a KVM_GET_MSRS after every KVM_SET_MSRS that writes a single MSR and
expects to succeeded.  The intent is to opportunistically verify that KVM
provides "read what you wrote" for all "durable" MSRs.  The PERF_CAPS test
was manually verifying this behavior, and while it seems kinda gratuitous,
the coverage is quite cheap from both a performance and maintenance cost,
i.e. I can't think of a reason _not_ to do it.

Applies on https://github.com/kvm-x86/linux/tree/next.

Sean Christopherson (21):
  KVM: x86: Rename kvm_init_msr_list() to clarify it inits multiple
    lists
  KVM: x86: Add a helper to query whether or not a vCPU has ever run
  KVM: x86: Add macros to track first...last VMX feature MSRs
  KVM: x86: Generate set of VMX feature MSRs using first/last
    definitions
  KVM: x86: Disallow writes to immutable feature MSRs after KVM_RUN
  KVM: x86/pmu: WARN and bug the VM if PMU is refreshed after vCPU has
    run
  KVM: x86/pmu: Zero out LBR capabilities during PMU refresh
  KVM: selftests: Split PMU caps sub-tests to avoid writing MSR after
    KVM_RUN
  KVM: selftests: Move 0/initial value PERF_CAPS checks to dedicated
    sub-test
  KVM: selftests: Assert that full-width PMC writes are supported if
    PDCM=1
  KVM: selftests: Print out failing MSR and value in vcpu_set_msr()
  KVM: selftests: Verify KVM preserves userspace writes to "durable"
    MSRs
  KVM: selftests: Drop now-redundant checks on PERF_CAPABILITIES writes
  KVM: selftests: Test all fungible features in PERF_CAPABILITIES
  KVM: selftests: Test all immutable non-format bits in
    PERF_CAPABILITIES
  KVM: selftests: Expand negative testing of guest writes to
    PERF_CAPABILITIES
  KVM: selftests: Test post-KVM_RUN writes to PERF_CAPABILITIES
  KVM: selftests: Drop "all done!" printf() from PERF_CAPABILITIES test
  KVM: selftests: Refactor LBR_FMT test to avoid use of separate macro
  KVM: selftests: Add negative testcase for PEBS format in
    PERF_CAPABILITIES
  KVM: selftests: Verify LBRs are disabled if vPMU is disabled

 arch/x86/kvm/cpuid.c                          |   2 +-
 arch/x86/kvm/mmu/mmu.c                        |   2 +-
 arch/x86/kvm/pmu.c                            |   3 +
 arch/x86/kvm/svm/svm.c                        |   2 +-
 arch/x86/kvm/vmx/pmu_intel.c                  |  10 +
 arch/x86/kvm/vmx/vmx.c                        |   8 +-
 arch/x86/kvm/x86.c                            | 103 +++++---
 arch/x86/kvm/x86.h                            |  13 +
 .../selftests/kvm/include/x86_64/processor.h  |  41 ++-
 .../selftests/kvm/x86_64/vmx_pmu_caps_test.c  | 248 ++++++++++++++----
 10 files changed, 342 insertions(+), 90 deletions(-)


base-commit: 62ef199250cd46fb66fe98267137b7f64e0b41b4
-- 
2.39.1.581.gbfd45094c4-goog

Powered by blists - more mailing lists