From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Oliver Upton <oupton@google.com>
Cc: kvm@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH 0/3] Handle monitor trap flag during instruction emulation
Date: Mon, 13 Jan 2020 14:35:04 -0800 [thread overview]
Message-ID: <20200113223504.GA14928@linux.intel.com> (raw)
In-Reply-To: <20200113221053.22053-1-oupton@google.com>
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.
next prev parent reply other threads:[~2020-01-13 22:35 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-13 22:10 [PATCH 0/3] Handle monitor trap flag during instruction emulation Oliver Upton
2020-01-13 22:10 ` [PATCH 1/3] KVM: x86: Add vendor-specific #DB payload delivery Oliver Upton
2020-01-13 22:52 ` Sean Christopherson
2020-01-13 23:16 ` Oliver Upton
2020-01-13 23:51 ` Oliver Upton
2020-01-13 22:10 ` [PATCH 2/3] KVM: x86: Emulate MTF when performing instruction emulation Oliver Upton
2020-01-14 0:05 ` Sean Christopherson
2020-01-14 17:58 ` Jim Mattson
2020-01-14 18:28 ` Sean Christopherson
2020-01-17 21:43 ` Jim Mattson
2020-01-15 22:51 ` Oliver Upton
2020-01-21 15:28 ` Paolo Bonzini
2020-01-13 22:10 ` [kvm-unit-tests PATCH 3/3] x86: VMX: Add tests for monitor trap flag Oliver Upton
2020-01-13 22:35 ` Sean Christopherson [this message]
2020-01-13 23:06 ` [PATCH 0/3] Handle monitor trap flag during instruction emulation Oliver Upton
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