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Message-ID: <946d0a77-eecb-5e30-716b-1d6cffd7f12c@amd.com>
Date: Mon, 5 Dec 2022 19:35:04 +0530
From: Santosh Shukla <santosh.shukla@....com>
To: Maxim Levitsky <mlevitsk@...hat.com>, kvm@...r.kernel.org
Cc: Sandipan Das <sandipan.das@....com>,
Paolo Bonzini <pbonzini@...hat.com>,
Jim Mattson <jmattson@...gle.com>,
Peter Zijlstra <peterz@...radead.org>,
Dave Hansen <dave.hansen@...ux.intel.com>,
Borislav Petkov <bp@...en8.de>,
Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
Josh Poimboeuf <jpoimboe@...nel.org>,
Daniel Sneddon <daniel.sneddon@...ux.intel.com>,
Jiaxi Chen <jiaxi.chen@...ux.intel.com>,
Babu Moger <babu.moger@....com>, linux-kernel@...r.kernel.org,
Jing Liu <jing2.liu@...el.com>,
Wyes Karny <wyes.karny@....com>, x86@...nel.org,
"H. Peter Anvin" <hpa@...or.com>,
Sean Christopherson <seanjc@...gle.com>, santosh.shukla@....com
Subject: Re: [PATCH v2 01/11] KVM: nSVM: don't sync back tlb_ctl on nested VM
exit
Hi Maxim,
On 11/30/2022 1:07 AM, Maxim Levitsky wrote:
> The CPU doesn't change TLB_CTL value as stated in the PRM (15.16.2):
>
nits:
s / PRM (15.16.2) / APM (15.16.1 - TLB Flush)
> "The VMRUN instruction reads, but does not change, the
> value of the TLB_CONTROL field"
>
> Therefore the KVM shouldn't do that either.
>
> Signed-off-by: Maxim Levitsky <mlevitsk@...hat.com>
> ---
> arch/x86/kvm/svm/nested.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
> index bc9cd7086fa972..37af0338da7c32 100644
> --- a/arch/x86/kvm/svm/nested.c
> +++ b/arch/x86/kvm/svm/nested.c
> @@ -1010,7 +1010,6 @@ int nested_svm_vmexit(struct vcpu_svm *svm)
> vmcb12->control.next_rip = vmcb02->control.next_rip;
>
> vmcb12->control.int_ctl = svm->nested.ctl.int_ctl;
> - vmcb12->control.tlb_ctl = svm->nested.ctl.tlb_ctl;
> vmcb12->control.event_inj = svm->nested.ctl.event_inj;
> vmcb12->control.event_inj_err = svm->nested.ctl.event_inj_err;
>
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