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

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Date:   Thu, 19 Jul 2018 09:31:33 +0000
From:   Tianyu Lan <Tianyu.Lan@...rosoft.com>
To:     Paolo Bonzini <pbonzini@...hat.com>,
        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 7/19/2018 4:57 PM, Paolo Bonzini wrote:
> 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. I will try to hyper-V people's ack.

> 
> 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
>>
>