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From: Paolo Bonzini <pbonzini@redhat.com>
To: Sean Christopherson <seanjc@google.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] KVM: nVMX: Dynamically compute max VMCS index for vmcs12
Date: Mon, 21 Jun 2021 18:39:04 +0200	[thread overview]
Message-ID: <c847e00a-e422-cdc9-3317-fbbd82b6e418@redhat.com> (raw)
In-Reply-To: <20210618214658.2700765-1-seanjc@google.com>

On 18/06/21 23:46, Sean Christopherson wrote:
> Calculate the max VMCS index for vmcs12 by walking the array to find the
> actual max index.  Hardcoding the index is prone to bitrot, and the
> calculation is only done on KVM bringup (albeit on every CPU, but there
> aren't _that_ many null entries in the array).
> 
> Fixes: 3c0f99366e34 ("KVM: nVMX: Add a TSC multiplier field in VMCS12")
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
> 
> Note, the vmx test in kvm-unit-tests will still fail using stock QEMU,
> as QEMU also hardcodes and overwrites the MSR.  The test passes if I
> hack KVM to ignore userspace (it was easier than rebuilding QEMU).

Queued, thanks.  Without having checked the kvm-unit-tests sources very 
thoroughly, this might be a configuration issue in kvm-unit-tests; in 
theory "-cpu host" (unlike "-cpu host,migratable=no") should not enable 
TSC scaling.

Paolo


  reply	other threads:[~2021-06-21 16:44 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-18 21:46 [PATCH] KVM: nVMX: Dynamically compute max VMCS index for vmcs12 Sean Christopherson
2021-06-21 16:39 ` Paolo Bonzini [this message]
2021-06-21 17:08   ` Sean Christopherson
2021-07-06  3:05     ` Hu, Robert
2021-07-06  5:42       ` Paolo Bonzini
2021-07-21 10:02     ` Hu, Robert
2021-07-21 16:18       ` Sean Christopherson
2021-07-22  2:43         ` Robert Hoo
2021-07-22  7:59 ` Maxim Levitsky
2021-07-22 15:04   ` Sean Christopherson

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