linux-kernel - Re: [PATCH v3 03/16] KVM: x86: Register Processor Trace interrupt hook iff PT enabled in guest

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Date:   Wed, 22 Sep 2021 08:24:00 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Will Deacon <will@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Marc Zyngier <maz@...nel.org>, Guo Ren <guoren@...nel.org>,
        Nick Hu <nickhu@...estech.com>,
        Greentime Hu <green.hu@...il.com>,
        Vincent Chen <deanbo422@...il.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>
Cc:     Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        James Morse <james.morse@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Stefano Stabellini <sstabellini@...nel.org>,
        linux-arm-kernel@...ts.infradead.org,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
        kvmarm@...ts.cs.columbia.edu, linux-csky@...r.kernel.org,
        linux-riscv@...ts.infradead.org, kvm@...r.kernel.org,
        xen-devel@...ts.xenproject.org,
        Artem Kashkanov <artem.kashkanov@...el.com>,
        Like Xu <like.xu.linux@...il.com>,
        Zhu Lingshan <lingshan.zhu@...el.com>
Subject: Re: [PATCH v3 03/16] KVM: x86: Register Processor Trace interrupt
 hook iff PT enabled in guest

On 22/09/21 02:05, Sean Christopherson wrote:
> Override the Processor Trace (PT) interrupt handler for guest mode if and
> only if PT is configured for host+guest mode, i.e. is being used
> independently by both host and guest.  If PT is configured for system
> mode, the host fully controls PT and must handle all events.
> 
> Fixes: 8479e04e7d6b ("KVM: x86: Inject PMI for KVM guest")
> Cc: stable@...r.kernel.org
> Cc: Like Xu <like.xu.linux@...il.com>
> Reported-by: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
> Reported-by: Artem Kashkanov <artem.kashkanov@...el.com>
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> ---
>   arch/x86/include/asm/kvm_host.h | 1 +
>   arch/x86/kvm/vmx/vmx.c          | 1 +
>   arch/x86/kvm/x86.c              | 5 ++++-
>   3 files changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 09b256db394a..1ea4943a73d7 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1494,6 +1494,7 @@ struct kvm_x86_init_ops {
>   	int (*disabled_by_bios)(void);
>   	int (*check_processor_compatibility)(void);
>   	int (*hardware_setup)(void);
> +	bool (*intel_pt_intr_in_guest)(void);
>   
>   	struct kvm_x86_ops *runtime_ops;
>   };
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index fada1055f325..f19d72136f77 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -7896,6 +7896,7 @@ static struct kvm_x86_init_ops vmx_init_ops __initdata = {
>   	.disabled_by_bios = vmx_disabled_by_bios,
>   	.check_processor_compatibility = vmx_check_processor_compat,
>   	.hardware_setup = hardware_setup,
> +	.intel_pt_intr_in_guest = vmx_pt_mode_is_host_guest,
>   
>   	.runtime_ops = &vmx_x86_ops,
>   };
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index fb6015f97f9e..ffc6c2d73508 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -8305,7 +8305,7 @@ static struct perf_guest_info_callbacks kvm_guest_cbs = {
>   	.is_in_guest		= kvm_is_in_guest,
>   	.is_user_mode		= kvm_is_user_mode,
>   	.get_guest_ip		= kvm_get_guest_ip,
> -	.handle_intel_pt_intr	= kvm_handle_intel_pt_intr,
> +	.handle_intel_pt_intr	= NULL,
>   };
>   
>   #ifdef CONFIG_X86_64
> @@ -11061,6 +11061,8 @@ int kvm_arch_hardware_setup(void *opaque)
>   	memcpy(&kvm_x86_ops, ops->runtime_ops, sizeof(kvm_x86_ops));
>   	kvm_ops_static_call_update();
>   
> +	if (ops->intel_pt_intr_in_guest && ops->intel_pt_intr_in_guest())
> +		kvm_guest_cbs.handle_intel_pt_intr = kvm_handle_intel_pt_intr;
>   	perf_register_guest_info_callbacks(&kvm_guest_cbs);
>   
>   	if (!kvm_cpu_cap_has(X86_FEATURE_XSAVES))
> @@ -11091,6 +11093,7 @@ int kvm_arch_hardware_setup(void *opaque)
>   void kvm_arch_hardware_unsetup(void)
>   {
>   	perf_unregister_guest_info_callbacks(&kvm_guest_cbs);
> +	kvm_guest_cbs.handle_intel_pt_intr = NULL;
>   
>   	static_call(kvm_x86_hardware_unsetup)();
>   }
> 

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