On Sun, Jan 06, 2019 at 01:57:24PM -0500, Mike Haboustak wrote: > [ Backport of upstream commit d391f1207067268261add0485f0f34503539c5b0 ] > > I was investigating an issue with seabios >= 1.10 which stopped working > for nested KVM on Hyper-V. The problem appears to be in > handle_ept_violation() function: when we do fast mmio we need to skip > the instruction so we do kvm_skip_emulated_instruction(). This, however, > depends on VM_EXIT_INSTRUCTION_LEN field being set correctly in VMCS. > However, this is not the case. > > Intel's manual doesn't mandate VM_EXIT_INSTRUCTION_LEN to be set when > EPT MISCONFIG occurs. While on real hardware it was observed to be set, > some hypervisors follow the spec and don't set it; we end up advancing > IP with some random value. > > I checked with Microsoft and they confirmed they don't fill > VM_EXIT_INSTRUCTION_LEN on EPT MISCONFIG. > > Fix the issue by doing instruction skip through emulator when running > nested. > > Fixes: 68c3b4d1676d870f0453c31d5a52e7e65c7448ae > Suggested-by: Radim Krčmář <rkrcmar@xxxxxxxxxx> > Suggested-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> > Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> > Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx> > Signed-off-by: Radim Krčmář <rkrcmar@xxxxxxxxxx> > Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx> > [mhaboustak: backport to 4.9.y] > Signed-off-by: Mike Haboustak <haboustak@xxxxxxxxx> > --- > arch/x86/kvm/vmx.c | 19 +++++++++++++++++-- > arch/x86/kvm/x86.c | 3 ++- > 2 files changed, 19 insertions(+), 3 deletions(-) Now queued up, thanks. greg k-h
