On Tue, Jan 28, 2020 at 01:27:10AM -0800, Oliver Upton wrote: > v1: http://lore.kernel.org/r/20200113221053.22053-1-oupton@xxxxxxxxxx > > v1 => v2: > - Don't split the #DB delivery by vendors. Unconditionally injecting > #DB payloads into the 'pending debug exceptions' field will cause KVM > to get stuck in a loop. Per the SDM, when hardware injects an event > resulting from this field's value, it is checked against the > exception interception bitmap. > - Address Sean's comments by injecting the VM-exit into L1 from > vmx_check_nested_events(). > - Added fix for nested INIT VM-exits + 'pending debug exceptions' field > as it was noticed in implementing v2. > - Drop Peter + Jim's Reviewed-by tags, as the patch set has changed > since v1. > > KVM already provides guests the ability to use the 'monitor trap flag' > VM-execution control. Support for this flag is provided by the fact that > KVM unconditionally forwards MTF VM-exits to the guest (if requested), > as KVM doesn't utilize MTF. While this provides support during hardware > instruction execution, it is insufficient for instruction emulation. > > Should L0 emulate an instruction on the behalf of L2, L0 should also > synthesize an MTF VM-exit into L1, should control be set. > > The first patch corrects a nuanced difference between the definition of > a #DB exception payload field and DR6 register. Mask off bit 12 which is > defined in the 'pending debug exceptions' field when applying to DR6, > since the payload field is said to be compatible with the aforementioned > VMCS field. > > The second patch sets the 'pending debug exceptions' VMCS field when > delivering an INIT signal VM-exit to L1, as described in the SDM. This > patch also introduces helpers for setting the 'pending debug exceptions' > VMCS field. > > The third patch massages KVM's handling of exception payloads with > regard to API compatibility. Rather than immediately injecting the > payload w/o opt-in, instead defer the payload + immediately inject > before completing a KVM_GET_VCPU_EVENTS. This maintains API > compatibility whilst correcting #DB behavior with regard to higher > priority VM-exit events. > > Fourth patch introduces MTF implementation for emulated instructions. > Identify if an MTF is due on an instruction boundary from > kvm_vcpu_do_singlestep(), however only deliver this VM-exit from > vmx_check_nested_events() to respect the relative prioritization to > other VM-exits. Since this augments the nested state, introduce a new > flag for (de)serialization. > > Last patch adds tests to kvm-unit-tests to assert the correctness of MTF > under several conditions (concurrent #DB trap, #DB fault, etc). These > tests pass under virtualization with this series as well as on > bare-metal. Based on tip of kvm/next as of Jan 28: f1b0bc14f2db ("KVM: x86: Use a typedef for fastop functions") > Oliver Upton (4): > KVM: x86: Mask off reserved bit from #DB exception payload > KVM: nVMX: Handle pending #DB when injecting INIT VM-exit > KVM: x86: Deliver exception payload on KVM_GET_VCPU_EVENTS > KVM: nVMX: Emulate MTF when performing instruction emulation > > arch/x86/include/asm/kvm_host.h | 1 + > arch/x86/include/uapi/asm/kvm.h | 1 + > arch/x86/kvm/svm.c | 1 + > arch/x86/kvm/vmx/nested.c | 60 ++++++++++++++++++++++++++++++++- > arch/x86/kvm/vmx/nested.h | 5 +++ > arch/x86/kvm/vmx/vmx.c | 22 ++++++++++++ > arch/x86/kvm/vmx/vmx.h | 3 ++ > arch/x86/kvm/x86.c | 52 +++++++++++++++++----------- > 8 files changed, 125 insertions(+), 20 deletions(-) > > -- > 2.25.0.341.g760bfbb309-goog >
