linux-kernel - Re: [PATCH V3 0/4] KVM/x86/hyper-V: Introduce PV guest address space mapping flush support

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Message-ID: <70536ba6-fe2e-04ae-7055-e1eef4e87c64@redhat.com>
Date:   Thu, 19 Jul 2018 10:57:42 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Tianyu Lan <Tianyu.Lan@...rosoft.com>
Cc:     "devel@...uxdriverproject.org" <devel@...uxdriverproject.org>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        "hpa@...or.com" <hpa@...or.com>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        KY Srinivasan <kys@...rosoft.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "rkrcmar@...hat.com" <rkrcmar@...hat.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "x86@...nel.org" <x86@...nel.org>,
        "Michael Kelley (EOSG)" <Michael.H.Kelley@...rosoft.com>,
        "vkuznets@...hat.com" <vkuznets@...hat.com>
Subject: Re: [PATCH V3 0/4] KVM/x86/hyper-V: Introduce PV guest address space
 mapping flush support

On 19/07/2018 10:39, Tianyu Lan wrote:
> Hyper-V provides a para-virtualization hypercall HvFlushGuestPhysicalAddressSpace
> to flush nested VM address space mapping in l1 hypervisor and it's to reduce overhead
> of flushing ept tlb among vcpus. The tradition way is to send IPIs to all affected
> vcpus and executes INVEPT on each vcpus. It will trigger several vmexits for IPI and
> INVEPT emulation. The pv hypercall can help to flush specified ept table on all vcpus
> via one single hypercall.

Thanks, this looks good apart from a global replace of EFAULT with
ENOTSUP (which can be done when applying).  Can I have an explicit ack
for patches 1 and 2 from the Hyper-V people?

Thanks,

Paolo

> Change since v2:
>        - Make ept_pointers_match as tristate "check", "match" and "mismatch".
>        Set "check" in vmx_set_cr3(), check all ept table pointers in hv_remote_flush_tlb()
>        and call hypercall when all ept pointers are same.
>        - Rename kvm_arch_hv_flush_remote_tlb with kvm_arch_flush_remote_tlb and
>        Rename kvm_x86_ops->hv_tlb_remote_flush with kvm_x86_ops->tlb_remote_flush
>        - Fix issue that ignore updating tlbs_dirty during calling kvm_arch_flush_remote_tlbs()
>        - Merge patch "KVM/VMX: Add identical ept table pointer check" and
>        patch "KVM/x86: Add tlb_remote_flush callback support for vmx"
> 
> Change since v1:
>        - Fix compilation error for non-x86 platform.
>        - Use ept_pointers_match to check condition of identical ept
>             table pointer and get ept pointer from struct vcpu_vmx->ept_pointer.
>        - Add hyperv_nested_flush_guest_mapping ftrace support
> 		     
> 
> 
> Lan Tianyu (4):
>   X86/Hyper-V: Add flush HvFlushGuestPhysicalAddressSpace hypercall
>     support
>   X86/Hyper-V: Add hyperv_nested_flush_guest_mapping ftrace support
>   KVM: Add tlb remote flush callback in kvm_x86_ops.
>   KVM/x86: Add tlb_remote_flush callback support for vmx
> 
>  arch/x86/hyperv/Makefile            |  2 +-
>  arch/x86/hyperv/nested.c            | 67 ++++++++++++++++++++++++++++++++++
>  arch/x86/include/asm/hyperv-tlfs.h  |  8 +++++
>  arch/x86/include/asm/kvm_host.h     | 11 ++++++
>  arch/x86/include/asm/mshyperv.h     |  2 ++
>  arch/x86/include/asm/trace/hyperv.h | 14 ++++++++
>  arch/x86/kvm/vmx.c                  | 72 ++++++++++++++++++++++++++++++++++++-
>  include/linux/kvm_host.h            |  7 ++++
>  virt/kvm/kvm_main.c                 |  3 +-
>  9 files changed, 183 insertions(+), 3 deletions(-)
>  create mode 100644 arch/x86/hyperv/nested.c
>