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From: "Radim Krčmář" <rkrcmar@redhat.com>
To: Bandan Das <bsd@redhat.com>
Cc: Jim Mattson <jmattson@google.com>,
	David Hildenbrand <david@redhat.com>,
	kvm list <kvm@vger.kernel.org>,
	Paolo Bonzini <pbonzini@redhat.com>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1 hypervisor
Date: Tue, 11 Jul 2017 22:22:27 +0200	[thread overview]
Message-ID: <20170711202227.GC3442@potion> (raw)
In-Reply-To: <jpg8tjuydax.fsf@linux.bootlegged.copy>

2017-07-11 15:38-0400, Bandan Das:
> Radim Krčmář <rkrcmar@redhat.com> writes:
> 
> > 2017-07-11 14:35-0400, Bandan Das:
> >> Jim Mattson <jmattson@google.com> writes:
> >> ...
> >> >>> I can find the definition for an vmexit in case of index >=
> >> >>> VMFUNC_EPTP_ENTRIES, but not for !vmcs12->eptp_list_address in the SDM.
> >> >>>
> >> >>> Can you give me a hint?
> >> >>
> >> >> I don't think there is. Since, we are basically emulating eptp switching
> >> >> for L2, this is a good check to have.
> >> >
> >> > There is nothing wrong with a hypervisor using physical page 0 for
> >> > whatever purpose it likes, including an EPTP list.
> >> 
> >> Right, but of all the things, a l1 hypervisor wanting page 0 for a eptp list
> >> address most likely means it forgot to initialize it. Whatever damage it does will
> >> still end up with vmfunc vmexit anyway.
> >
> > Most likely, but not certainly.  I also don't see a to diverge from the
> > spec here.
> 
> Actually, this is a specific case where I would like to diverge from the spec.
> But then again, it's L1 shooting itself in the foot and this would be a rarely
> used code path, so, I am fine removing it.

Thanks, we're not here to judge the guest, but to provide a bare-metal
experience. :)

  reply	other threads:[~2017-07-11 20:22 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-07-10 20:49 [PATCH v4 0/3] Expose VMFUNC to the nested hypervisor Bandan Das
2017-07-10 20:49 ` [PATCH v4 1/3] KVM: vmx: Enable VMFUNCs Bandan Das
2017-07-10 20:49 ` [PATCH v4 2/3] KVM: nVMX: Enable VMFUNC for the L1 hypervisor Bandan Das
2017-07-10 20:49 ` [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching " Bandan Das
2017-07-11  7:51   ` David Hildenbrand
2017-07-11  8:39     ` Paolo Bonzini
2017-07-11 13:52     ` Radim Krčmář
2017-07-11 18:05       ` Bandan Das
2017-07-11 19:12         ` Radim Krčmář
2017-07-11 19:34           ` Bandan Das
2017-07-11 17:58     ` Bandan Das
2017-07-11 18:22       ` Jim Mattson
2017-07-11 18:35         ` Bandan Das
2017-07-11 19:13           ` Radim Krčmář
2017-07-11 19:38             ` Bandan Das
2017-07-11 20:22               ` Radim Krčmář [this message]
2017-07-11 20:45                 ` Bandan Das
2017-07-12 13:41                   ` Radim Krčmář
2017-07-12 18:04                     ` Bandan Das
2017-07-11 18:24       ` Bandan Das
2017-07-11 19:32         ` Radim Krčmář
2017-07-11 19:50           ` Bandan Das
2017-07-11 20:21             ` Radim Krčmář
2017-07-11 20:34               ` Bandan Das
2017-07-11 20:45                 ` Radim Krčmář
2017-07-11 21:08                   ` Bandan Das
2017-07-12 13:24                     ` Radim Krčmář
2017-07-12 18:11                       ` Bandan Das
2017-07-12 19:18                         ` Radim Krčmář
2017-07-17 17:58               ` Bandan Das
2017-07-19  9:30                 ` Radim Krčmář
2017-07-19 17:54                   ` Bandan Das
2017-07-13 15:39       ` David Hildenbrand
2017-07-13 17:08         ` Bandan Das

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