On Wed, Oct 30, 2024, Maxim Levitsky wrote: > On Fri, 2024-09-06 at 18:18 -0400, Maxim Levitsky wrote: > > Recently we came up upon a failure where likely the guest writes > > 0xff4547ceb1600000 to MSR_KERNEL_GS_BASE and later on, qemu > > sets this value via KVM_PUT_MSRS, and is rejected by the > > kernel, likely due to not being canonical in 4 level paging. > > > > One of the way to trigger this is to make the guest enter SMM, > > which causes paging to be disabled, which SMM bios re-enables > > but not the whole 5 level. MSR_KERNEL_GS_BASE on the other > > hand continues to contain old value. > > > > I did some reverse engineering and to my surprise I found out > > that both Intel and AMD indeed ignore CR4.LA57 when doing > > canonical checks on this and other msrs and/or other arch > > registers (like GDT base) which contain linear addresses. > > > > V2: addressed a very good feedback from Chao Gao. Thanks! > > > > V3: also fix the nested VMX, and also fix the > > MSR_IA32_SYSENTER_EIP / MSR_IA32_SYSENTER_ESP > > > > V4: > > - added PT and PEBS msrs > > - corrected emulation of SGDT/SIDT/STR/SLDT instructions > > - corrected canonical checks for TLB invalidation instructions > > > > Best regards, > > Maxim Levitsky > > > > Maxim Levitsky (4): > > KVM: x86: drop x86.h include from cpuid.h > > KVM: x86: implement emul_is_noncanonical_address using > > is_noncanonical_address > > KVM: x86: model canonical checks more precisely > > KVM: nVMX: fix canonical check of vmcs12 HOST_RIP > > > > arch/x86/kvm/cpuid.h | 1 - > > arch/x86/kvm/emulate.c | 15 ++++++----- > > arch/x86/kvm/kvm_emulate.h | 5 ++++ > > arch/x86/kvm/mmu.h | 1 + > > arch/x86/kvm/mmu/mmu.c | 2 +- > > arch/x86/kvm/vmx/hyperv.c | 1 + > > arch/x86/kvm/vmx/nested.c | 35 +++++++++++++++++--------- > > arch/x86/kvm/vmx/pmu_intel.c | 2 +- > > arch/x86/kvm/vmx/sgx.c | 5 ++-- > > arch/x86/kvm/vmx/vmx.c | 4 +-- > > arch/x86/kvm/x86.c | 13 +++++++--- > > arch/x86/kvm/x86.h | 49 ++++++++++++++++++++++++++++++++++-- > > 12 files changed, 102 insertions(+), 31 deletions(-) > > > > -- > > 2.26.3 > > > > > > Hi, > A very gentle ping on this patch series. Heh, good timing, I literally (like, 2 seconds ago) applied this (still need to test before you'll see a "thank you" email).
