linux-kernel - Re: [PATCH 0/2] Expose VMFUNC to the nested hypervisor

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Date:   Fri, 30 Jun 2017 13:58:31 -0400
From:   Bandan Das <bsd@...hat.com>
To:     Jim Mattson <jmattson@...gle.com>
Cc:     kvm list <kvm@...r.kernel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/2] Expose VMFUNC to the nested hypervisor

Jim Mattson <jmattson@...gle.com> writes:

> Isn't McAfee DeepSAFE defunct? Are there any other consumers of EPTP switching?

I don't know of any real users but I think we should be providing this functionality to
the L1 hypervisor :)

IIRC, Xen lets you use EPTP switching as part of VM introspection ?

Bandan


> On Thu, Jun 29, 2017 at 4:29 PM, Bandan Das <bsd@...hat.com> wrote:
>> These patches expose eptp switching/vmfunc to the nested hypervisor. Testing with
>> kvm-unit-tests seems to work ok.
>>
>> If the guest hypervisor enables vmfunc/eptp switching, a "shadow" eptp list
>> address page is written to the VMCS. Initially, it would be unpopulated which
>> would result in a vmexit with exit reason 59. This hooks to handle_vmfunc()
>> to rewrite vmcs12->ept_pointer to reload the mmu and get a new root hpa.
>> This new shadow ept pointer is written to the shadow eptp list in the given
>> index. A next vmfunc call to switch to the given index would succeed without
>> an exit.
>>
>> Bandan Das (2):
>>   KVM: nVMX: Implement EPTP switching for the L1 hypervisor
>>   KVM: nVMX: Advertise VMFUNC to L1 hypervisor
>>
>>  arch/x86/include/asm/vmx.h |   9 ++++
>>  arch/x86/kvm/vmx.c         | 122 +++++++++++++++++++++++++++++++++++++++++++++
>>  2 files changed, 131 insertions(+)
>>
>> --
>> 2.9.4
>>