This is the next version of this patch series. In V5 I adopted Sean Christopherson's suggestion to make .set_efer return a negative error (-ENOMEM in this case) which in most cases in kvm propagates to the userspace. I noticed though that wrmsr emulation code doesn't do this and instead it injects #GP to the guest on _any_ error. So I fixed the wrmsr code to behave in a similar way to the rest of the kvm code. (#GP only on a positive error value, and forward the negative error to the userspace) I had to adjust one wrmsr handler (xen_hvm_config) to stop it from returning negative values so that new WRMSR emulation behavior doesn't break it. This patch was only compile tested. The memory allocation failure was tested by always returning -ENOMEM from svm_allocate_nested. The nested allocation itself was tested by countless attempts to run nested guests, do nested migration on both my AMD and Intel machines. I wasn't able to break it. Changes from V5: addressed Sean Christopherson's review feedback. Changes from V6: rebased the code on latest kvm/queue Best regards, Maxim Levitsky Maxim Levitsky (4): KVM: x86: xen_hvm_config: cleanup return values KVM: x86: report negative values from wrmsr emulation to userspace KVM: x86: allow kvm_x86_ops.set_efer to return an error value KVM: nSVM: implement on demand allocation of the nested state arch/x86/include/asm/kvm_host.h | 2 +- arch/x86/kvm/emulate.c | 4 +-- arch/x86/kvm/svm/nested.c | 42 ++++++++++++++++++++++ arch/x86/kvm/svm/svm.c | 64 ++++++++++++++++++--------------- arch/x86/kvm/svm/svm.h | 10 +++++- arch/x86/kvm/vmx/vmx.c | 6 ++-- arch/x86/kvm/x86.c | 39 ++++++++++---------- 7 files changed, 114 insertions(+), 53 deletions(-) -- 2.26.2
