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From: Sean Christopherson <seanjc@google.com>
To: Like Xu <like.xu@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	Kan Liang <kan.liang@linux.intel.com>,
	Dave Hansen <dave.hansen@intel.com>,
	wei.w.wang@intel.com, Borislav Petkov <bp@alien8.de>,
	kvm@vger.kernel.org, x86@kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 7/9] KVM: vmx/pmu: Add Arch LBR emulation and its VMCS field
Date: Wed, 3 Mar 2021 09:26:05 -0800	[thread overview]
Message-ID: <YD/GrQAl1NMPHXFj@google.com> (raw)
In-Reply-To: <20210303135756.1546253-8-like.xu@linux.intel.com>

On Wed, Mar 03, 2021, Like Xu wrote:
> New VMX controls bits for Arch LBR are added. When bit 21 in vmentry_ctrl
> is set, VM entry will write the value from the "Guest IA32_LBR_CTL" guest
> state field to IA32_LBR_CTL. When bit 26 in vmexit_ctrl is set, VM exit
> will clear IA32_LBR_CTL after the value has been saved to the "Guest
> IA32_LBR_CTL" guest state field.

...

> @@ -2529,7 +2532,8 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf,
>  	      VM_EXIT_LOAD_IA32_EFER |
>  	      VM_EXIT_CLEAR_BNDCFGS |
>  	      VM_EXIT_PT_CONCEAL_PIP |
> -	      VM_EXIT_CLEAR_IA32_RTIT_CTL;
> +	      VM_EXIT_CLEAR_IA32_RTIT_CTL |
> +	      VM_EXIT_CLEAR_IA32_LBR_CTL;

So, how does MSR_ARCH_LBR_CTL get restored on the host?  What if the host wants
to keep _its_ LBR recording active while the guest is running?

>  	if (adjust_vmx_controls(min, opt, MSR_IA32_VMX_EXIT_CTLS,
>  				&_vmexit_control) < 0)
>  		return -EIO;
> @@ -2553,7 +2557,8 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf,
>  	      VM_ENTRY_LOAD_IA32_EFER |
>  	      VM_ENTRY_LOAD_BNDCFGS |
>  	      VM_ENTRY_PT_CONCEAL_PIP |
> -	      VM_ENTRY_LOAD_IA32_RTIT_CTL;
> +	      VM_ENTRY_LOAD_IA32_RTIT_CTL |
> +	      VM_ENTRY_LOAD_IA32_LBR_CTL;
>  	if (adjust_vmx_controls(min, opt, MSR_IA32_VMX_ENTRY_CTLS,
>  				&_vmentry_control) < 0)
>  		return -EIO;
> -- 
> 2.29.2
> 

  reply	other threads:[~2021-03-03 20:56 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-03 13:57 [PATCH v3 0/9] KVM: x86/pmu: Guest Architectural LBR Enabling Like Xu
2021-03-03 13:57 ` [PATCH v3 1/9] perf/x86/intel: Fix a comment about guest LBR support Like Xu
2021-03-03 16:49   ` Sean Christopherson
2021-03-03 13:57 ` [PATCH v3 2/9] perf/x86/lbr: Simplify the exposure check for the LBR_INFO registers Like Xu
2021-03-03 13:57 ` [PATCH v3 3/9] perf/x86/lbr: Skip checking for the existence of LBR_TOS for Arch LBR Like Xu
2021-03-03 13:57 ` [PATCH v3 4/9] perf/x86/lbr: Use GFP_ATOMIC for cpuc->lbr_xsave memory allocation Like Xu
2021-03-03 13:57 ` [PATCH v3 5/9] KVM: vmx/pmu: Add MSR_ARCH_LBR_DEPTH emulation for Arch LBR Like Xu
2021-03-03 16:58   ` Sean Christopherson
2021-03-04  2:30     ` Xu, Like
2021-03-04 16:12       ` Sean Christopherson
2021-03-05  2:33         ` Xu, Like
2021-03-03 13:57 ` [PATCH v3 6/9] KVM: vmx/pmu: Add MSR_ARCH_LBR_CTL " Like Xu
2021-03-03 17:19   ` Sean Christopherson
2021-03-04  2:58     ` Xu, Like
2021-03-04 16:25       ` Sean Christopherson
2021-03-03 13:57 ` [PATCH v3 7/9] KVM: vmx/pmu: Add Arch LBR emulation and its VMCS field Like Xu
2021-03-03 17:26   ` Sean Christopherson [this message]
2021-03-04  3:02     ` Xu, Like
2021-03-04 17:23       ` Sean Christopherson
2021-03-05  6:35         ` Xu, Like
2021-03-03 13:57 ` [PATCH v3 8/9] KVM: x86: Expose Architectural LBR CPUID leaf Like Xu
2021-03-03 17:34   ` Sean Christopherson
2021-03-03 18:01     ` Sean Christopherson
2021-03-03 13:57 ` [PATCH v3 9/9] KVM: x86: Add XSAVE Support for Architectural LBRs Like Xu
2021-03-03 18:03   ` Sean Christopherson
2021-03-04  3:43     ` Like Xu
2021-03-04 16:31       ` Sean Christopherson
2021-03-05  2:57         ` Xu, Like
2021-03-03 13:57 ` [kvm-unit-tests PATCH] x86: Update guest LBR tests for Architectural LBR Like Xu
2021-03-03 18:05   ` Sean Christopherson

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