| Message ID | 20200113221053.22053-1-oupton@google.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | Handle monitor trap flag during instruction emulation | expand |
On Mon, Jan 13, 2020 at 02:10:50PM -0800, Oliver Upton wrote: > 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 fixes the handling of #DB payloads for both Intel and > AMD. To support MTF, KVM must also populate the 'pending debug > exceptions' field, rather than directly manipulating the debug register > state. Additionally, the exception payload associated with #DB is said > to be compatible with the 'pending debug exceptions' field in VMX. This > does not map cleanly into an AMD DR6 register, requiring bit 12 (enabled > breakpoint on Intel, reserved MBZ on AMD) to be masked off. > > The second patch implements MTF under instruction emulation by adding > vendor-specific hooks to kvm_skip_emulated_instruction(). Should any > non-debug exception be pending before this call, MTF will follow event > delivery. Otherwise, an MTF VM-exit may be synthesized directly into L1. > > Third patch introduces tests to kvm-unit-tests. These tests path both > under virtualization and on bare-metal. > > Oliver Upton (2): > KVM: x86: Add vendor-specific #DB payload delivery > KVM: x86: Emulate MTF when performing instruction emulation > > arch/x86/include/asm/kvm_host.h | 2 ++ > arch/x86/kvm/svm.c | 25 +++++++++++++++++++++ > arch/x86/kvm/vmx/nested.c | 2 +- > arch/x86/kvm/vmx/nested.h | 5 +++++ > arch/x86/kvm/vmx/vmx.c | 39 ++++++++++++++++++++++++++++++++- > arch/x86/kvm/x86.c | 27 ++++++----------------- > 6 files changed, 78 insertions(+), 22 deletions(-) > > -- What commit is this series based on? It doesn't apply cleanly on the current kvm/master or kvm/queue.
On Mon, Jan 13, 2020 at 02:35:04PM -0800, Sean Christopherson wrote: > On Mon, Jan 13, 2020 at 02:10:50PM -0800, Oliver Upton wrote: > > 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 fixes the handling of #DB payloads for both Intel and > > AMD. To support MTF, KVM must also populate the 'pending debug > > exceptions' field, rather than directly manipulating the debug register > > state. Additionally, the exception payload associated with #DB is said > > to be compatible with the 'pending debug exceptions' field in VMX. This > > does not map cleanly into an AMD DR6 register, requiring bit 12 (enabled > > breakpoint on Intel, reserved MBZ on AMD) to be masked off. > > > > The second patch implements MTF under instruction emulation by adding > > vendor-specific hooks to kvm_skip_emulated_instruction(). Should any > > non-debug exception be pending before this call, MTF will follow event > > delivery. Otherwise, an MTF VM-exit may be synthesized directly into L1. > > > > Third patch introduces tests to kvm-unit-tests. These tests path both > > under virtualization and on bare-metal. > > > > Oliver Upton (2): > > KVM: x86: Add vendor-specific #DB payload delivery > > KVM: x86: Emulate MTF when performing instruction emulation > > > > arch/x86/include/asm/kvm_host.h | 2 ++ > > arch/x86/kvm/svm.c | 25 +++++++++++++++++++++ > > arch/x86/kvm/vmx/nested.c | 2 +- > > arch/x86/kvm/vmx/nested.h | 5 +++++ > > arch/x86/kvm/vmx/vmx.c | 39 ++++++++++++++++++++++++++++++++- > > arch/x86/kvm/x86.c | 27 ++++++----------------- > > 6 files changed, 78 insertions(+), 22 deletions(-) > > > > -- > > What commit is this series based on? It doesn't apply cleanly on the > current kvm/master or kvm/queue. Blech. I use torvalds/master for initial review before sending out (woo, Gerrit!). Seems I sent out my set based on torvalds, not kvm. I'll rebase in v2 (while addressing your comments). Thanks for the prompt reply, Sean :) -- Best, Oliver