From: Paolo Bonzini <pbonzini@redhat.com>
To: Liran Alon <liran.alon@oracle.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>,
kvm list <kvm@vger.kernel.org>,
mtosatti@redhat.com,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
qemu-devel@nongnu.org, Jim Mattson <jmattson@google.com>,
rth@twiddle.net
Subject: Re: [QEMU PATCH v2 0/2]: KVM: i386: Add support for save and restore nested state
Date: Thu, 8 Nov 2018 18:02:58 +0100 [thread overview]
Message-ID: <d29d27ba-f34e-6dd6-4eec-8e75971269e3@redhat.com> (raw)
In-Reply-To: <939A6255-306C-431C-8799-0D56A30A3BD5@oracle.com>
On 08/11/2018 10:57, Liran Alon wrote:
>
>
>> On 8 Nov 2018, at 11:50, Paolo Bonzini <pbonzini@redhat.com> wrote:
>>
>> On 08/11/2018 01:45, Jim Mattson wrote:
>>> I have no attachments to the current design. I had used a data[] blob,
>>> because I didn't think userspace would have any need to know what was
>>> in there. However, I am now seeing the error of my ways. For example,
>>> the userspace instruction emulator needs to know the contents of the
>>> vmcs12 to emulate instructions when in guest mode.
>>
>> Yeah, we're probably going to have to document the KVM vmcs12 structure,
>> possibly moving it to uapi. But that's a different thing from
>> save/restore state, which can use the 4K or 8K data[] blob.
>>
>> Paolo
>
> But regardless of if we document vmcs12 or not, the current blob we
> have today should be separated to well-defined blobs/structs (cached_vmcs12
> and cached_shadow_vmcs12) and each blob should have a relevant flag that specifies
> it is valid (saved by kernel or requested to be restored by userspace).
> Additional future nested-state should be added as additional
> well-defined blobs/structs with appropriate flags.
We are somewhat limited by the ABI of the released kernel versions, and
it's unlikely that the structure will change in the short term. So I
think it's okay if we just define that the first 4K of data are the VMCS
and the second 8K are the shadow VMCS, whenever format=0 in the
kvm_nested_state struct.
Paolo
> Then, in QEMU, each such well-defined blob/struct should have it’s own subsection with a relevant .needed() method.
> This will allow us to preserve required backwards compatibility.
>
> Agreed?
>
> -Liran
>
WARNING: multiple messages have this Message-ID (diff)
From: Paolo Bonzini <pbonzini@redhat.com>
To: Liran Alon <liran.alon@oracle.com>
Cc: Jim Mattson <jmattson@google.com>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
Eduardo Habkost <ehabkost@redhat.com>,
kvm list <kvm@vger.kernel.org>,
mtosatti@redhat.com, rth@twiddle.net, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [QEMU PATCH v2 0/2]: KVM: i386: Add support for save and restore nested state
Date: Thu, 8 Nov 2018 18:02:58 +0100 [thread overview]
Message-ID: <d29d27ba-f34e-6dd6-4eec-8e75971269e3@redhat.com> (raw)
In-Reply-To: <939A6255-306C-431C-8799-0D56A30A3BD5@oracle.com>
On 08/11/2018 10:57, Liran Alon wrote:
>
>
>> On 8 Nov 2018, at 11:50, Paolo Bonzini <pbonzini@redhat.com> wrote:
>>
>> On 08/11/2018 01:45, Jim Mattson wrote:
>>> I have no attachments to the current design. I had used a data[] blob,
>>> because I didn't think userspace would have any need to know what was
>>> in there. However, I am now seeing the error of my ways. For example,
>>> the userspace instruction emulator needs to know the contents of the
>>> vmcs12 to emulate instructions when in guest mode.
>>
>> Yeah, we're probably going to have to document the KVM vmcs12 structure,
>> possibly moving it to uapi. But that's a different thing from
>> save/restore state, which can use the 4K or 8K data[] blob.
>>
>> Paolo
>
> But regardless of if we document vmcs12 or not, the current blob we
> have today should be separated to well-defined blobs/structs (cached_vmcs12
> and cached_shadow_vmcs12) and each blob should have a relevant flag that specifies
> it is valid (saved by kernel or requested to be restored by userspace).
> Additional future nested-state should be added as additional
> well-defined blobs/structs with appropriate flags.
We are somewhat limited by the ABI of the released kernel versions, and
it's unlikely that the structure will change in the short term. So I
think it's okay if we just define that the first 4K of data are the VMCS
and the second 8K are the shadow VMCS, whenever format=0 in the
kvm_nested_state struct.
Paolo
> Then, in QEMU, each such well-defined blob/struct should have it’s own subsection with a relevant .needed() method.
> This will allow us to preserve required backwards compatibility.
>
> Agreed?
>
> -Liran
>
next prev parent reply other threads:[~2018-11-08 17:02 UTC|newest]
Thread overview: 96+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-16 12:46 [QEMU PATCH v2 0/2]: KVM: i386: Add support for save and restore nested state Liran Alon
2018-09-16 12:46 ` [Qemu-devel] " Liran Alon
2018-09-16 12:46 ` [QEMU PATCH v2 1/2] i386: Compile CPUX86State xsave_buf only when support KVM or HVF Liran Alon
2018-09-16 12:46 ` [Qemu-devel] " Liran Alon
2018-09-16 12:46 ` [QEMU PATCH v2 2/2] KVM: i386: Add support for save and restore nested state Liran Alon
2018-09-16 12:46 ` [Qemu-devel] " Liran Alon
2018-10-08 17:21 ` [QEMU PATCH v2 0/2]: " Liran Alon
2018-10-08 17:21 ` [Qemu-devel] " Liran Alon
2018-10-15 18:10 ` Liran Alon
2018-10-15 18:10 ` [Qemu-devel] " Liran Alon
2018-10-31 1:03 ` Liran Alon
2018-10-31 1:03 ` [Qemu-devel] " Liran Alon
2018-10-31 18:17 ` Eduardo Habkost
2018-10-31 18:17 ` [Qemu-devel] " Eduardo Habkost
2018-10-31 18:19 ` Paolo Bonzini
2018-10-31 18:19 ` [Qemu-devel] " Paolo Bonzini
2018-10-31 18:50 ` Liran Alon
2018-10-31 18:50 ` [Qemu-devel] " Liran Alon
2018-10-31 18:59 ` Dr. David Alan Gilbert
2018-10-31 18:59 ` [Qemu-devel] " Dr. David Alan Gilbert
2018-10-31 23:17 ` Liran Alon
2018-10-31 23:17 ` [Qemu-devel] " Liran Alon
2018-11-01 13:10 ` Dr. David Alan Gilbert
2018-11-01 13:10 ` [Qemu-devel] " Dr. David Alan Gilbert
2018-11-01 15:23 ` Liran Alon
2018-11-01 15:23 ` [Qemu-devel] " Liran Alon
2018-11-01 15:56 ` Dr. David Alan Gilbert
2018-11-01 15:56 ` [Qemu-devel] " Dr. David Alan Gilbert
2018-11-01 16:45 ` Jim Mattson via Qemu-devel
2018-11-01 16:45 ` [Qemu-devel] " Jim Mattson
2018-11-02 3:46 ` Liran Alon
2018-11-02 3:46 ` [Qemu-devel] " Liran Alon
2018-11-02 9:40 ` Paolo Bonzini
2018-11-02 9:40 ` [Qemu-devel] " Paolo Bonzini
2018-11-02 12:35 ` Dr. David Alan Gilbert
2018-11-02 12:35 ` [Qemu-devel] " Dr. David Alan Gilbert
2018-11-02 12:40 ` Daniel P. Berrangé
2018-11-02 12:40 ` [Qemu-devel] " Daniel P. Berrangé
2018-11-04 22:12 ` Paolo Bonzini
2018-11-04 22:12 ` [Qemu-devel] " Paolo Bonzini
2018-11-02 12:59 ` Liran Alon
2018-11-02 12:59 ` [Qemu-devel] " Liran Alon
2018-11-02 16:44 ` Jim Mattson via Qemu-devel
2018-11-02 16:44 ` [Qemu-devel] " Jim Mattson
2018-11-02 16:58 ` Daniel P. Berrangé
2018-11-02 16:58 ` [Qemu-devel] " Daniel P. Berrangé
2018-11-02 17:01 ` Jim Mattson via Qemu-devel
2018-11-02 17:01 ` [Qemu-devel] " Jim Mattson
2018-11-02 16:54 ` Daniel P. Berrangé
2018-11-02 16:54 ` [Qemu-devel] " Daniel P. Berrangé
2018-11-02 16:58 ` Dr. David Alan Gilbert
2018-11-02 16:58 ` [Qemu-devel] " Dr. David Alan Gilbert
2018-11-04 22:19 ` Paolo Bonzini
2018-11-04 22:19 ` [Qemu-devel] " Paolo Bonzini
2018-11-12 16:18 ` Daniel P. Berrangé
2018-11-12 16:18 ` [Qemu-devel] " Daniel P. Berrangé
2018-11-12 16:50 ` Dr. David Alan Gilbert
2018-11-12 16:50 ` [Qemu-devel] " Dr. David Alan Gilbert
2018-11-12 16:53 ` Paolo Bonzini
2018-11-12 16:53 ` [Qemu-devel] " Paolo Bonzini
2018-11-12 16:54 ` Daniel P. Berrangé
2018-11-12 16:54 ` [Qemu-devel] " Daniel P. Berrangé
2018-11-13 0:00 ` Liran Alon
2018-11-13 0:00 ` [Qemu-devel] " Liran Alon
2018-11-13 0:07 ` Jim Mattson via Qemu-devel
2018-11-13 0:07 ` [Qemu-devel] " Jim Mattson
2018-11-13 0:09 ` Liran Alon
2018-11-13 0:09 ` [Qemu-devel] " Liran Alon
2018-11-12 23:58 ` Liran Alon
2018-11-12 23:58 ` [Qemu-devel] " Liran Alon
2018-11-02 16:39 ` Jim Mattson via Qemu-devel
2018-11-02 16:39 ` [Qemu-devel] " Jim Mattson
2018-11-03 2:02 ` Liran Alon
2018-11-03 2:02 ` [Qemu-devel] " Liran Alon
2018-11-08 0:13 ` Liran Alon
2018-11-08 0:13 ` [Qemu-devel] " Liran Alon
2018-11-08 0:45 ` Jim Mattson via Qemu-devel
2018-11-08 0:45 ` [Qemu-devel] " Jim Mattson
2018-11-08 9:50 ` Paolo Bonzini
2018-11-08 9:50 ` [Qemu-devel] " Paolo Bonzini
2018-11-08 9:57 ` Liran Alon
2018-11-08 9:57 ` [Qemu-devel] " Liran Alon
2018-11-08 17:02 ` Paolo Bonzini [this message]
2018-11-08 17:02 ` Paolo Bonzini
2018-11-08 18:41 ` Liran Alon
2018-11-08 18:41 ` [Qemu-devel] " Liran Alon
2018-11-08 20:34 ` Paolo Bonzini
2018-11-08 20:34 ` [Qemu-devel] " Paolo Bonzini
2018-11-12 14:51 ` Dr. David Alan Gilbert
2018-11-12 14:51 ` [Qemu-devel] " Dr. David Alan Gilbert
2018-11-01 19:03 ` Liran Alon
2018-11-01 19:03 ` [Qemu-devel] " Liran Alon
2018-11-01 19:07 ` Dr. David Alan Gilbert
2018-11-01 19:07 ` [Qemu-devel] " Dr. David Alan Gilbert
2018-11-01 19:41 ` Jim Mattson via Qemu-devel
2018-11-01 19:41 ` [Qemu-devel] " Jim Mattson
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