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

[Paolo Bonzini <pbonzini@xxxxxxxxxx>]

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@xxxxxxxxxxxxxxx
> Cc: Like Xu <like.xu.linux@xxxxxxxxx>
> Reported-by: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
> Reported-by: Artem Kashkanov <artem.kashkanov@xxxxxxxxx>
> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> ---
>   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@xxxxxxxxxx>