From: Sean Christopherson <seanjc@google.com>
To: Vineeth Pillai <viremana@linux.microsoft.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"K. Y. Srinivasan" <kys@microsoft.com>,
x86@kernel.org, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org,
Lan Tianyu <Tianyu.Lan@microsoft.com>,
Michael Kelley <mikelley@microsoft.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
Wei Liu <wei.liu@kernel.org>,
Stephen Hemminger <sthemmin@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>
Subject: Re: [PATCH 1/7] hyperv: Detect Nested virtualization support for SVM
Date: Thu, 8 Apr 2021 15:24:44 +0000 [thread overview]
Message-ID: <YG8gPI6NZHGBc3Zl@google.com> (raw)
In-Reply-To: <af87c25e-78c6-5859-e1c1-2aa07d087a25@linux.microsoft.com>
On Thu, Apr 08, 2021, Vineeth Pillai wrote:
> Hi Vitaly,
>
> On 4/8/21 7:06 AM, Vitaly Kuznetsov wrote:
> > - if (ms_hyperv.hints & HV_X64_ENLIGHTENED_VMCS_RECOMMENDED) {
> > + /*
> > + * AMD does not need enlightened VMCS as VMCB is already a
> > + * datastructure in memory.
> > Well, VMCS is also a structure in memory, isn't it? It's just that we
> > don't have a 'clean field' concept for it and we can't use normal memory
> > accesses.
Technically, you can use normal memory accesses, so long as software guarantees
the VMCS isn't resident in the VMCS cache and knows the field offsets for the
underlying CPU. The lack of an architecturally defined layout is the biggest
issue, e.g. tacking on dirty bits through a PV ABI would be trivial.
> Yes, you are right. I was referring to the fact that we cant use normal
> memory accesses, but is a bit mis-worded.
If you slot in "architectural" it will read nicely, i.e. "VMCB is already an
architectural datastructure in memory".
next prev parent reply other threads:[~2021-04-08 15:24 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-07 14:41 [PATCH 0/7] Hyper-V nested virt enlightenments for SVM Vineeth Pillai
2021-04-07 14:41 ` [PATCH 1/7] hyperv: Detect Nested virtualization support " Vineeth Pillai
2021-04-07 16:09 ` Borislav Petkov
2021-04-07 19:55 ` Michael Kelley
2021-04-07 22:48 ` Sean Christopherson
2021-04-08 13:26 ` Vineeth Pillai
2021-04-08 11:06 ` Vitaly Kuznetsov
2021-04-08 13:15 ` Vineeth Pillai
2021-04-08 15:24 ` Sean Christopherson [this message]
2021-04-09 12:23 ` Vineeth Pillai
2021-04-07 14:41 ` [PATCH 2/7] hyperv: SVM enlightened TLB flush support flag Vineeth Pillai
2021-04-07 19:56 ` Michael Kelley
2021-04-08 13:45 ` Vineeth Pillai
2021-04-07 14:41 ` [PATCH 3/7] KVM: x86: hyper-v: Move the remote TLB flush logic out of vmx Vineeth Pillai
2021-04-08 11:14 ` Vitaly Kuznetsov
2021-04-08 13:18 ` Vineeth Pillai
2021-04-07 14:41 ` [PATCH 4/7] KVM: SVM: hyper-v: Nested enlightenments in VMCB Vineeth Pillai
2021-04-08 15:44 ` Paolo Bonzini
2021-04-09 12:24 ` Vineeth Pillai
2021-04-07 14:41 ` [PATCH 5/7] KVM: SVM: hyper-v: Remote TLB flush for SVM Vineeth Pillai
2021-04-08 11:18 ` Vitaly Kuznetsov
2021-04-08 13:19 ` Vineeth Pillai
2021-04-07 14:41 ` [PATCH 6/7] KVM: SVM: hyper-v: Enlightened MSR-Bitmap support Vineeth Pillai
2021-04-08 11:22 ` Vitaly Kuznetsov
2021-04-08 15:47 ` Paolo Bonzini
2021-04-07 14:41 ` [PATCH 7/7] KVM: SVM: hyper-v: Direct Virtual Flush support Vineeth Pillai
2021-04-08 11:25 ` Vitaly Kuznetsov
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