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SubjectRe: [PATCH v5 0/4] Add bus lock VM exit support
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On 06/11/20 10:03, Chenyi Qiang wrote:
> This patch series add the support for bus lock VM exit in KVM. It is a
> sub-feature of bus lock detection. When it is enabled by the VMM, the
> processor generates a "Bus Lock" VM exit following execution of an
> instruction if the processor detects that one or more bus locks were
> caused the instruction was being executed (due to either direct access
> by the instruction or stuffed accesses like through A/D updates).
>
> Bus lock VM exit will introduce a new modifier bit (bit 26) in
> exit_reason field in VMCS which indicates bus lock VM exit is preempted
> by a higher priority VM exit. The first patch is to apply Sean's
> refactor for vcpu_vmx.exit_reason as a preparation patch for bus lock
> VM exit support.
>
> The second patch is the refactor for vcpu->run->flags. Bus lock VM exit
> will introduce a new field in the flags to inform the userspace that
> there's a bus lock detected in guest. It's also a preparation patch.
>
> The third patch is the concrete enabling working for bus lock VM exit.
> Add the support to set the capability to enable bus lock VM exit. The
> current implementation is just exiting to userspace when handling the
> bus lock detected in guest.
>
> The detail of throttling policy in user space is still to be discussed.
> We may enforce ratelimit on bus lock in guest, inject some sleep time,
> or... We hope to get more ideas on this.
>
> Document for Bus Lock Detection is now available at the latest "Intel
> Architecture Instruction Set Extensions Programming Reference".
>
> Document Link:
> https://software.intel.com/content/www/us/en/develop/download/intel-architecture-instruction-set-extensions-programming-reference.html
>
> ---
>
> Changelogs
>
> v4->v5:
> - rebase on top on v5.10-rc2
> - add preparation patch that reset the vcpu->run->flags at the beginning
> of the vcpu_run.(Suggested by Sean)
> - set the KVM_RUN_BUS_LOCK for all bus lock exit to avoid checking both
> exit_reason and run->flags
> - add the document to introduce the new kvm capability
> (KVM_CAP_X86_BUS_LOCK_EXIT)
> - v4:https://lore.kernel.org/lkml/20201012033542.4696-1-chenyi.qiang@intel.com/
>
>
> v3->v4:
> - rebase on top of v5.9
> - some code cleanup.
> - v3:https://lore.kernel.org/lkml/20200910083751.26686-1-chenyi.qiang@intel.com/
>
> v2->v3:
> - use a bitmap to get/set the capability of bus lock detection. we support
> exit and off mode currently.
> - put the handle of exiting to userspace in vmx.c, thus no need to
> define a shadow to track vmx->exit_reason.bus_lock_detected.
> - remove the vcpu->stats.bus_locks since every bus lock exits to userspace.
> - v2:https://lore.kernel.org/lkml/20200817033604.5836-1-chenyi.qiang@intel.com/
>
> v1->v2:
> - resolve Vitaly's comment to introduce the KVM_EXIT_BUS_LOCK and a
> capability to enable it.
> - add the support to exit to user space when handling bus locks.
> - extend the vcpu->run->flags to indicate bus lock detected for other
> exit reasons when exiting to user space.
> - v1:https://lore.kernel.org/lkml/20200628085341.5107-1-chenyi.qiang@intel.com/
>
> ---
>
> Chenyi Qiang (3):
> KVM: X86: Reset the vcpu->run->flags at the beginning of vcpu_run
> KVM: VMX: Enable bus lock VM exit
> KVM: X86: Add the Document for KVM_CAP_X86_BUS_LOCK_EXIT
>
> Sean Christopherson (1):
> KVM: VMX: Convert vcpu_vmx.exit_reason to a union
>
> Documentation/virt/kvm/api.rst | 45 ++++++++++++-
> arch/x86/include/asm/kvm_host.h | 7 ++
> arch/x86/include/asm/vmx.h | 1 +
> arch/x86/include/asm/vmxfeatures.h | 1 +
> arch/x86/include/uapi/asm/kvm.h | 1 +
> arch/x86/include/uapi/asm/vmx.h | 4 +-
> arch/x86/kvm/vmx/capabilities.h | 6 ++
> arch/x86/kvm/vmx/nested.c | 42 +++++++-----
> arch/x86/kvm/vmx/vmx.c | 105 +++++++++++++++++++----------
> arch/x86/kvm/vmx/vmx.h | 25 ++++++-
> arch/x86/kvm/x86.c | 28 +++++++-
> include/uapi/linux/kvm.h | 5 ++
> 12 files changed, 214 insertions(+), 56 deletions(-)
>

Queued, thanks. I have replaced KVM_RUN_BUS_LOCK with
KVM_RUN_X86_BUS_LOCK, though.

Paolo

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