linux-kernel - Re: [PATCH v2 12/15] KVM: x86/vmx: Disable Arch LBREn bit in #DB and warm reset

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Message-ID: <195c26b7-783f-fc27-1a60-b0dcd1de01ac@gmail.com>
Date:   Thu, 22 Dec 2022 19:22:42 +0800
From:   Like Xu <like.xu.linux@...il.com>
To:     Yang Weijiang <weijiang.yang@...el.com>
Cc:     kan.liang@...ux.intel.com, wei.w.wang@...el.com, seanjc@...gle.com,
        pbonzini@...hat.com, jmattson@...gle.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 12/15] KVM: x86/vmx: Disable Arch LBREn bit in #DB and
 warm reset

On 25/11/2022 12:06 pm, Yang Weijiang wrote:
> +static void disable_arch_lbr_ctl(struct kvm_vcpu *vcpu)
> +{
> +	struct lbr_desc *lbr_desc = vcpu_to_lbr_desc(vcpu);
> +	struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
> +
> +	if (kvm_cpu_cap_has(X86_FEATURE_ARCH_LBR) &&
> +	    test_bit(INTEL_PMC_IDX_FIXED_VLBR, pmu->pmc_in_use) &&
> +	    lbr_desc->event) {
> +		u64 ctl = vmcs_read64(GUEST_IA32_LBR_CTL);
> +
> +		vmcs_write64(GUEST_IA32_LBR_CTL, ctl & ~ARCH_LBR_CTL_LBREN);
> +	}
> +}
> +
>   static void vmx_inject_exception(struct kvm_vcpu *vcpu)
>   {
>   	struct kvm_queued_exception *ex = &vcpu->arch.exception;
> @@ -1738,6 +1752,9 @@ static void vmx_inject_exception(struct kvm_vcpu *vcpu)
>   	vmcs_write32(VM_ENTRY_INTR_INFO_FIELD, intr_info);
>   
>   	vmx_clear_hlt(vcpu);
> +
> +	if (ex->vector == DB_VECTOR)
> +		disable_arch_lbr_ctl(vcpu);

Please verify this with KUT testcase, once I failed and did not confirm
if it is a hardware issue. Good Luck.

>   }