On Wed, Aug 03, 2022, Maxim Levitsky wrote:
> @@ -4486,28 +4482,23 @@ static int svm_leave_smm(struct kvm_vcpu *vcpu, const union kvm_smram *smram)
> {
> struct vcpu_svm *svm = to_svm(vcpu);
> struct kvm_host_map map, map_save;
> - u64 saved_efer, vmcb12_gpa;
> struct vmcb *vmcb12;
> int ret;
>
> - const char *smstate = (const char *)smram;
To shorten line lengths, what about grabbing smram64 here?
const kvm_smram_state_64 *smram64 = &smram->smram64;
IMO, makes things a little easier to read too.
> -
> if (!guest_cpuid_has(vcpu, X86_FEATURE_LM))
> return 0;
>
> /* Non-zero if SMI arrived while vCPU was in guest mode. */
> - if (!GET_SMSTATE(u64, smstate, 0x7ed8))
> + if (!smram->smram64.svm_guest_flag)
> return 0;
>
> if (!guest_cpuid_has(vcpu, X86_FEATURE_SVM))
> return 1;
>
> - saved_efer = GET_SMSTATE(u64, smstate, 0x7ed0);
> - if (!(saved_efer & EFER_SVME))
> + if (!(smram->smram64.efer & EFER_SVME))
> return 1;
>
> - vmcb12_gpa = GET_SMSTATE(u64, smstate, 0x7ee0);
> - if (kvm_vcpu_map(vcpu, gpa_to_gfn(vmcb12_gpa), &map) == -EINVAL)
> + if (kvm_vcpu_map(vcpu, gpa_to_gfn(smram->smram64.svm_guest_vmcb_gpa), &map) == -EINVAL)
Eww, this is horrifically wrong. KVM will explode if kvm_vcpu_map() returns
-EFAULT, e.g. if guest memory is not backed by struct page and memremap() fails.
Not to mention that it's comically fragile too.
Can you add a patch to this series to drop the "== -EINVAL"?
And there's another one lurking just out of sight in this diff.
> return 1;
>
> ret = 1;
> @@ -4533,7 +4524,7 @@ static int svm_leave_smm(struct kvm_vcpu *vcpu, const union kvm_smram *smram)
> vmcb12 = map.hva;
> nested_copy_vmcb_control_to_cache(svm, &vmcb12->control);
> nested_copy_vmcb_save_to_cache(svm, &vmcb12->save);
> - ret = enter_svm_guest_mode(vcpu, vmcb12_gpa, vmcb12, false);
> + ret = enter_svm_guest_mode(vcpu, smram->smram64.svm_guest_vmcb_gpa, vmcb12, false);
>
> if (ret)
> goto unmap_save;
> --
> 2.26.3
>
