linux-kernel - Re: [RFC PATCH v5 071/104] KVM: TDX: restore debug store when TD exit

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Date:   Fri, 15 Apr 2022 16:20:56 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     isaku.yamahata@...el.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     isaku.yamahata@...il.com, Jim Mattson <jmattson@...gle.com>,
        erdemaktas@...gle.com, Connor Kuehl <ckuehl@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>
Subject: Re: [RFC PATCH v5 071/104] KVM: TDX: restore debug store when TD exit

On 3/4/22 20:49, isaku.yamahata@...el.com wrote:
> From: Isaku Yamahata <isaku.yamahata@...el.com>
> 
> Because debug store is clobbered, restore it on TD exit.
> 
> Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
> ---
>   arch/x86/events/intel/ds.c | 1 +
>   arch/x86/kvm/vmx/tdx.c     | 1 +
>   2 files changed, 2 insertions(+)
> 
> diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c
> index 376cc3d66094..cdba4227ad3b 100644
> --- a/arch/x86/events/intel/ds.c
> +++ b/arch/x86/events/intel/ds.c
> @@ -2256,3 +2256,4 @@ void perf_restore_debug_store(void)
>   
>   	wrmsrl(MSR_IA32_DS_AREA, (unsigned long)ds);
>   }
> +EXPORT_SYMBOL_GPL(perf_restore_debug_store);
> diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> index 3cb2fbd1c12c..37cf7d43435d 100644
> --- a/arch/x86/kvm/vmx/tdx.c
> +++ b/arch/x86/kvm/vmx/tdx.c
> @@ -620,6 +620,7 @@ fastpath_t tdx_vcpu_run(struct kvm_vcpu *vcpu)
>   	tdx_vcpu_enter_exit(vcpu, tdx);
>   
>   	tdx_user_return_update_cache();
> +	perf_restore_debug_store();
>   	tdx_restore_host_xsave_state(vcpu);
>   	tdx->host_state_need_restore = true;
>   

Reviewed-by: Paolo Bonzini <pbonzini@...hat.com>