The highlight is a rework of the userspace MSR access code to automatically suppress errors on disallowed accesses to advertised-but-unsupported MSRs. Unfortunately, actually removing all of the !host_initiated exemptions in KVM is decidely non-trivial, so realizing most the benefits will have to wait (though this should make life much easier for CET enabling). The lowlight is a rework of the x2APIC ICR handling. KVM jumped through hoops to deal with Intel CPUs storing the full 64-bit value at the ICR offset in the vAPIC page, and then AMD (x2AVIC) came along and continued to split the value to the legacy ICR and ICR2 offsets. *sigh* The following changes since commit 47ac09b91befbb6a235ab620c32af719f8208399: Linux 6.11-rc4 (2024-08-18 13:17:27 -0700) are available in the Git repository at: https://github.com/kvm-x86/linux.git tags/kvm-x86-misc-6.12 for you to fetch changes up to 4ca077f26d885cbc97e742a5f3572aac244a0f8a: KVM: x86: Remove some unused declarations (2024-09-09 20:12:43 -0700) ---------------------------------------------------------------- KVM x86 misc changes for 6.12 - Advertise AVX10.1 to userspace (effectively prep work for the "real" AVX10 functionality that is on the horizon). - Rework common MSR handling code to suppress errors on userspace accesses to unsupported-but-advertised MSRs. This will allow removing (almost?) all of KVM's exemptions for userspace access to MSRs that shouldn't exist based on the vCPU model (the actual cleanup is non-trivial future work). - Rework KVM's handling of x2APIC ICR, again, because AMD (x2AVIC) splits the 64-bit value into the legacy ICR and ICR2 storage, whereas Intel (APICv) stores the entire 64-bit value a the ICR offset. - Fix a bug where KVM would fail to exit to userspace if one was triggered by a fastpath exit handler. - Add fastpath handling of HLT VM-Exit to expedite re-entering the guest when there's already a pending wake event at the time of the exit. - Finally fix the RSM vs. nested VM-Enter WARN by forcing the vCPU out of guest mode prior to signalling SHUTDOWN (architecturally, the SHUTDOWN is supposed to hit L1, not L2). ---------------------------------------------------------------- Li Chen (1): KVM: x86: Use this_cpu_ptr() in kvm_user_return_msr_cpu_online Sean Christopherson (26): KVM: SVM: Disallow guest from changing userspace's MSR_AMD64_DE_CFG value KVM: x86: Move MSR_TYPE_{R,W,RW} values from VMX to x86, as enums KVM: x86: Rename KVM_MSR_RET_INVALID to KVM_MSR_RET_UNSUPPORTED KVM: x86: Refactor kvm_x86_ops.get_msr_feature() to avoid kvm_msr_entry KVM: x86: Rename get_msr_feature() APIs to get_feature_msr() KVM: x86: Refactor kvm_get_feature_msr() to avoid struct kvm_msr_entry KVM: x86: Funnel all fancy MSR return value handling into a common helper KVM: x86: Hoist x86.c's global msr_* variables up above kvm_do_msr_access() KVM: x86: Suppress failures on userspace access to advertised, unsupported MSRs KVM: x86: Suppress userspace access failures on unsupported, "emulated" MSRs KVM: x86: Enforce x2APIC's must-be-zero reserved ICR bits KVM: x86: Move x2APIC ICR helper above kvm_apic_write_nodecode() KVM: x86: Re-split x2APIC ICR into ICR+ICR2 for AMD (x2AVIC) KVM: selftests: Open code vcpu_run() equivalent in guest_printf test KVM: selftests: Report unhandled exceptions on x86 as regular guest asserts KVM: selftests: Add x86 helpers to play nice with x2APIC MSR #GPs KVM: selftests: Skip ICR.BUSY test in xapic_state_test if x2APIC is enabled KVM: selftests: Test x2APIC ICR reserved bits KVM: selftests: Verify the guest can read back the x2APIC ICR it wrote KVM: selftests: Play nice with AMD's AVIC errata KVM: x86: Re-enter guest if WRMSR(X2APIC_ICR) fastpath is successful KVM: x86: Dedup fastpath MSR post-handling logic KVM: x86: Exit to userspace if fastpath triggers one on instruction skip KVM: x86: Reorganize code in x86.c to co-locate vCPU blocking/running helpers KVM: x86: Add fastpath handling of HLT VM-Exits KVM: x86: Forcibly leave nested if RSM to L2 hits shutdown Tao Su (1): KVM: x86: Advertise AVX10.1 CPUID to userspace Thorsten Blum (1): KVM: x86: Optimize local variable in start_sw_tscdeadline() Yue Haibing (1): KVM: x86: Remove some unused declarations arch/x86/include/asm/cpuid.h | 1 + arch/x86/include/asm/kvm-x86-ops.h | 2 +- arch/x86/include/asm/kvm_host.h | 5 +- arch/x86/kvm/cpuid.c | 30 +- arch/x86/kvm/lapic.c | 75 +- arch/x86/kvm/lapic.h | 1 - arch/x86/kvm/mmu.h | 2 - arch/x86/kvm/mmu/mmu_internal.h | 2 - arch/x86/kvm/reverse_cpuid.h | 8 + arch/x86/kvm/smm.c | 24 +- arch/x86/kvm/svm/svm.c | 44 +- arch/x86/kvm/vmx/main.c | 4 +- arch/x86/kvm/vmx/vmx.c | 10 +- arch/x86/kvm/vmx/vmx.h | 4 - arch/x86/kvm/vmx/x86_ops.h | 2 +- arch/x86/kvm/x86.c | 841 +++++++++++---------- arch/x86/kvm/x86.h | 28 +- tools/testing/selftests/kvm/guest_print_test.c | 19 +- tools/testing/selftests/kvm/include/x86_64/apic.h | 21 +- tools/testing/selftests/kvm/lib/x86_64/processor.c | 8 +- .../selftests/kvm/x86_64/xapic_state_test.c | 54 +- 21 files changed, 681 insertions(+), 504 deletions(-)
