From: Haiwei Li <lihaiwei.kernel@gmail.com>
To: Jim Mattson <jmattson@google.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
kvm list <kvm@vger.kernel.org>,
Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <seanjc@google.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Joerg Roedel <joro@8bytes.org>, Haiwei Li <lihaiwei@tencent.com>
Subject: Re: [PATCH] KVM: VMX: Check the corresponding bits according to the intel sdm
Date: Tue, 23 Mar 2021 12:42:11 +0800 [thread overview]
Message-ID: <CAB5KdOb+rwsP0Pf_=_OmQYq94+V0FjqWB0uOA4V1MdUpPd7Rtg@mail.gmail.com> (raw)
In-Reply-To: <CALMp9eST+qAnXLpzPpORn6piVMNi3xY=P0KmP-cKixtCNAOH9Q@mail.gmail.com>
On Tue, Mar 23, 2021 at 11:16 AM Jim Mattson <jmattson@google.com> wrote:
>
> On Mon, Mar 22, 2021 at 7:37 PM <lihaiwei.kernel@gmail.com> wrote:
> >
> > From: Haiwei Li <lihaiwei@tencent.com>
> >
> > According to IA-32 SDM Vol.3D "A.1 BASIC VMX INFORMATION", two inspections
> > are missing.
> > * Bit 31 is always 0. Earlier versions of this manual specified that the
> > VMCS revision identifier was a 32-bit field in bits 31:0 of this MSR. For
> > all processors produced prior to this change, bit 31 of this MSR was read
> > as 0.
>
> For all *Intel* processors produced prior to this change, bit 31 of
> this MSR may have been 0. However, a conforming hypervisor may have
> selected a full 32-bit VMCS revision identifier with the high bit set
> for nested VMX. Furthermore, there are other vendors, such as VIA,
> which have implemented the VMX extensions, and they, too, may have
> selected a full 32-bit VMCS revision identifier with the high bit set.
> Intel should know better than to change the documentation after the
> horse is out of the barn.
Got it, thanks.
>
> What, exactly, is the value you are adding with this check?
I did this just to match the sdm.
--
Haiwei Li
next prev parent reply other threads:[~2021-03-23 4:43 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-23 2:37 [PATCH] KVM: VMX: Check the corresponding bits according to the intel sdm lihaiwei.kernel
2021-03-23 3:16 ` Jim Mattson
2021-03-23 4:42 ` Haiwei Li [this message]
2021-03-25 13:22 ` Haiwei Li
2021-03-25 15:49 ` Sean Christopherson
2021-03-26 0:39 ` Haiwei Li
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