On Wed, 23 Sep 2020 15:45:27 -0700 Sean Christopherson <sean.j.christopherson@xxxxxxxxx> wrote: > This series introduces a concept we've discussed a few times in x86 land. > The crux of the problem is that x86 has a few cases where KVM could > theoretically encounter a software or hardware bug deep in a call stack > without any sane way to propagate the error out to userspace. > > Another use case would be for scenarios where letting the VM live will > do more harm than good, e.g. we've been using KVM_BUG_ON for early TDX > enabling as botching anything related to secure paging all but guarantees > there will be a flood of WARNs and error messages because lower level PTE > operations will fail if an upper level operation failed. > > The basic idea is to WARN_ONCE if a bug is encountered, kick all vCPUs out > to userspace, and mark the VM as bugged so that no ioctls() can be issued > on the VM or its devices/vCPUs. I think this makes a lot of sense. Are there other user space interactions where we want to generate an error for a bugged VM, e.g. via eventfd? And can we make the 'bugged' information available to user space in a structured way? > > RFC as I've done nowhere near enough testing to verify that rejecting the > ioctls(), evicting running vCPUs, etc... works as intended. > > Sean Christopherson (3): > KVM: Export kvm_make_all_cpus_request() for use in marking VMs as > bugged > KVM: Add infrastructure and macro to mark VM as bugged > KVM: x86: Use KVM_BUG/KVM_BUG_ON to handle bugs that are fatal to the > VM > > arch/x86/kvm/svm/svm.c | 2 +- > arch/x86/kvm/vmx/vmx.c | 23 ++++++++++++-------- > arch/x86/kvm/x86.c | 4 ++++ > include/linux/kvm_host.h | 45 ++++++++++++++++++++++++++++++++-------- > virt/kvm/kvm_main.c | 11 +++++----- > 5 files changed, 61 insertions(+), 24 deletions(-) >
