Re: [PATCH 3/3] KVM: nSVM: more strict SMM checks when returning to nested guest
From: Maxim Levitsky
Date: Mon Aug 31 2020 - 10:26:52 EST
On Mon, 2020-08-31 at 15:01 +0300, Dan Carpenter wrote:
> Hi Maxim,
>
> url: https://github.com/0day-ci/linux/commits/Maxim-Levitsky/Few-nSVM-bugfixes/20200828-003025
> base: https://git.kernel.org/pub/scm/virt/kvm/kvm.git linux-next
> config: x86_64-randconfig-m001-20200827 (attached as .config)
> compiler: gcc-9 (Debian 9.3.0-15) 9.3.0
>
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
>
> smatch warnings:
> arch/x86/kvm/svm/svm.c:3915 svm_pre_leave_smm() warn: should this be a bitwise op?
>
> # https://github.com/0day-ci/linux/commit/e2317f8eb1f0e9f731ddbe66ab175be19f3bdaf1
> git remote add linux-review https://github.com/0day-ci/linux
> git fetch --no-tags linux-review Maxim-Levitsky/Few-nSVM-bugfixes/20200828-003025
> git checkout e2317f8eb1f0e9f731ddbe66ab175be19f3bdaf1
> vim +3915 arch/x86/kvm/svm/svm.c
>
> ed19321fb657121 arch/x86/kvm/svm.c Sean Christopherson 2019-04-02 3900 static int svm_pre_leave_smm(struct kvm_vcpu *vcpu, const char *smstate)
> 0234bf885236a41 arch/x86/kvm/svm.c Ladi Prosek 2017-10-11 3901 {
> 05cade71cf3b925 arch/x86/kvm/svm.c Ladi Prosek 2017-10-11 3902 struct vcpu_svm *svm = to_svm(vcpu);
> 8c5fbf1a7231078 arch/x86/kvm/svm.c KarimAllah Ahmed 2019-01-31 3903 struct kvm_host_map map;
> 59cd9bc5b03f0ba arch/x86/kvm/svm/svm.c Vitaly Kuznetsov 2020-07-10 3904 int ret = 0;
> 05cade71cf3b925 arch/x86/kvm/svm.c Ladi Prosek 2017-10-11 3905
> e2317f8eb1f0e9f arch/x86/kvm/svm/svm.c Maxim Levitsky 2020-08-27 3906 if (guest_cpuid_has(vcpu, X86_FEATURE_LM)) {
> e2317f8eb1f0e9f arch/x86/kvm/svm/svm.c Maxim Levitsky 2020-08-27 3907 u64 saved_efer = GET_SMSTATE(u64, smstate, 0x7ed0);
> e2317f8eb1f0e9f arch/x86/kvm/svm/svm.c Maxim Levitsky 2020-08-27 3908 u64 guest = GET_SMSTATE(u64, smstate, 0x7ed8);
> e2317f8eb1f0e9f arch/x86/kvm/svm/svm.c Maxim Levitsky 2020-08-27 3909 u64 vmcb = GET_SMSTATE(u64, smstate, 0x7ee0);
> 05cade71cf3b925 arch/x86/kvm/svm.c Ladi Prosek 2017-10-11 3910
> ed19321fb657121 arch/x86/kvm/svm.c Sean Christopherson 2019-04-02 3911 if (guest) {
> e2317f8eb1f0e9f arch/x86/kvm/svm/svm.c Maxim Levitsky 2020-08-27 3912 if (!guest_cpuid_has(vcpu, X86_FEATURE_SVM))
> 9ec19493fb86d6d arch/x86/kvm/svm.c Sean Christopherson 2019-04-02 3913 return 1;
> e2317f8eb1f0e9f arch/x86/kvm/svm/svm.c Maxim Levitsky 2020-08-27 3914
> e2317f8eb1f0e9f arch/x86/kvm/svm/svm.c Maxim Levitsky 2020-08-27 @3915 if (!(saved_efer && EFER_SVME))
> ^^
> It looks like bitwise AND was intended.
Oops. Thanks!
Best regards,
Maxim Levitskky
>
> e2317f8eb1f0e9f arch/x86/kvm/svm/svm.c Maxim Levitsky 2020-08-27 3916 return 1;
> e2317f8eb1f0e9f arch/x86/kvm/svm/svm.c Maxim Levitsky 2020-08-27 3917
> e2317f8eb1f0e9f arch/x86/kvm/svm/svm.c Maxim Levitsky 2020-08-27 3918 if (kvm_vcpu_map(&svm->vcpu,
> e2317f8eb1f0e9f arch/x86/kvm/svm/svm.c Maxim Levitsky 2020-08-27 3919 gpa_to_gfn(vmcb), &map) == -EINVAL)
> e2317f8eb1f0e9f arch/x86/kvm/svm/svm.c Maxim Levitsky 2020-08-27 3920 return 1;
> e2317f8eb1f0e9f arch/x86/kvm/svm/svm.c Maxim Levitsky 2020-08-27 3921
> e2317f8eb1f0e9f arch/x86/kvm/svm/svm.c Maxim Levitsky 2020-08-27 3922 ret = enter_svm_guest_mode(svm, vmcb, map.hva);
> 69c9dfa24bb7bac arch/x86/kvm/svm/svm.c Paolo Bonzini 2020-05-13 3923 kvm_vcpu_unmap(&svm->vcpu, &map, true);
> 05cade71cf3b925 arch/x86/kvm/svm.c Ladi Prosek 2017-10-11 3924 }
> e2317f8eb1f0e9f arch/x86/kvm/svm/svm.c Maxim Levitsky 2020-08-27 3925 }
> 59cd9bc5b03f0ba arch/x86/kvm/svm/svm.c Vitaly Kuznetsov 2020-07-10 3926
> 59cd9bc5b03f0ba arch/x86/kvm/svm/svm.c Vitaly Kuznetsov 2020-07-10 3927 return ret;
> 0234bf885236a41 arch/x86/kvm/svm.c Ladi Prosek 2017-10-11 3928 }
>
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx