From: Krish Sadhukhan <krish.sadhukhan@oracle.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Jim Mattson <jmattson@google.com>, kvm list <kvm@vger.kernel.org>
Subject: Re: [PATCH 1/2 v2] KVM: nVMX: KVM needs to unset "unrestricted guest" VM-execution control in vmcs02 if vmcs12 doesn't set it
Date: Tue, 28 Apr 2020 10:38:54 -0700 [thread overview]
Message-ID: <a5bf92bd-d4df-8d6c-8df2-9c993b31459a@oracle.com> (raw)
In-Reply-To: <11ce961c-d98c-3c4c-06a7-3c0f8336a340@redhat.com>
On 4/28/20 1:14 AM, Paolo Bonzini wrote:
> On 28/04/20 09:25, Krish Sadhukhan wrote:
>>> Absolutely. Unrestricted guest requires EPT, but EPT is invisible to
>>> the guest. (Currently EPT requires guest MAXPHYADDR = host MAXPHYADDR,
>>> in the sense that the guest can detect that the host is lying about
>>> MAXPHYADDR; but that is really a bug that I hope will be fixed in 5.8,
>>> relaxing the requirement to guest MAXPHYADDR <= host PHYADDR).
>> Should EPT for the nested guest be set up in the normal way (PML4E ->
>> PDPTE-> PDE -> PTE) when GUEST_CR0.PE is zero ? Or does it have to be a
>> special set up like only the PTEs are needed because no protection and
>> no paging are used ?
> I don't understand. When EPT is in use, the vmcs02 CR3 is simply set to
> the vmcs12 CR3.
Sorry, I should have framed my question in a better way.
My question is how should L1 in the test code set up EPTP for L2 when
L2 is an unrestricted guest with no protection (GUEST_CR0.PE = 0) and no
paging (GUEST_CR0.PG = 0) ? Should EPTP in test code be set up in the
same way as when L2 is an unrestricted guest with protection and paging
enabled ?
Getting confused by legacy 16-bit Real Mode and an unrestricted guest in
Real Mode. :-)
> Paolo
>
next prev parent reply other threads:[~2020-04-28 17:39 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-15 18:30 [PATCH 0/2 v2] kvm-unit-test: nVMX: Test Selector and Base Address fields of Guest Segment registers Krish Sadhukhan
2020-04-15 18:30 ` [PATCH 1/2 v2] KVM: nVMX: KVM needs to unset "unrestricted guest" VM-execution control in vmcs02 if vmcs12 doesn't set it Krish Sadhukhan
2020-04-15 19:30 ` Sean Christopherson
2020-04-15 20:18 ` Jim Mattson
2020-04-16 9:18 ` Paolo Bonzini
2020-04-18 1:29 ` Krish Sadhukhan
2020-04-18 1:55 ` Sean Christopherson
2020-04-18 9:53 ` Paolo Bonzini
2020-04-20 15:12 ` Sean Christopherson
2020-04-28 7:25 ` Krish Sadhukhan
2020-04-28 8:14 ` Paolo Bonzini
2020-04-28 17:38 ` Krish Sadhukhan [this message]
2020-04-28 18:00 ` Jim Mattson
2020-04-15 18:30 ` [PATCH 2/2 v2] kvm-unit-tests: nVMX: Test Selector and Base Address fields of Guest Segment Registers on vmentry of nested guests Krish Sadhukhan
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