On 14.11.2025 15:22, Grygorii Strashko wrote:
> --- a/xen/arch/x86/hvm/Kconfig
> +++ b/xen/arch/x86/hvm/Kconfig
> @@ -35,6 +35,18 @@ config INTEL_VMX
> If your system includes a processor with Intel VT-x support, say Y.
> If in doubt, say Y.
>
> +config VMTRACE
> + bool "HW VM tracing support"
> + depends on INTEL_VMX
> + default y
> + help
> + Enables HW VM tracing support which allows to configure HW processor
> + features (vmtrace_op) to enable capturing information about software
> + execution using dedicated hardware facilities with minimal interference
> + to the software being traced. The trace data can be retrieved using
> buffer
> + shared between Xen and domain
> + (see XENMEM_acquire_resource(XENMEM_resource_vmtrace_buf)).
Please check adjacent options above or ...
> config HVM_FEP
> bool "HVM Forced Emulation Prefix support (UNSUPPORTED)" if UNSUPPORTED
> default DEBUG
... below for how proper indentation would look like here.
> --- a/xen/arch/x86/hvm/vmx/vmcs.c
> +++ b/xen/arch/x86/hvm/vmx/vmcs.c
> @@ -307,6 +307,7 @@ static int vmx_init_vmcs_config(bool bsp)
> rdmsrl(MSR_IA32_VMX_MISC, _vmx_misc_cap);
>
> /* Check whether IPT is supported in VMX operation. */
> +#ifdef CONFIG_VMTRACE
This imo wants to move ahead of the comment. (Feels a little like I may have
said so already, but it may well have been in the context of a different
recent patch.)
> @@ -772,13 +775,24 @@ static inline int hvm_vmtrace_get_option(
>
> return -EOPNOTSUPP;
> }
> +#else
> +/*
> + * Function declaration(s) here are used without definition(s) to make
> compiler
> + * happy when VMTRACE=n, compiler DCE will eliminate unused code.
> + */
> +int hvm_vmtrace_output_position(struct vcpu *v, uint64_t *pos);
> +#endif
>
> static inline int hvm_vmtrace_reset(struct vcpu *v)
> {
> +#ifdef CONFIG_VMTRACE
> if ( hvm_funcs.vmtrace_reset )
> return alternative_call(hvm_funcs.vmtrace_reset, v);
>
> return -EOPNOTSUPP;
> +#else
> + return -EOPNOTSUPP;
> +#endif
No #else please and the #endif moved up.
> --- a/xen/arch/x86/vm_event.c
> +++ b/xen/arch/x86/vm_event.c
> @@ -253,7 +253,8 @@ void vm_event_fill_regs(vm_event_request_t *req)
> req->data.regs.x86.shadow_gs = ctxt.shadow_gs;
> req->data.regs.x86.dr6 = ctxt.dr6;
>
> - if ( hvm_vmtrace_output_position(curr, &req->data.regs.x86.vmtrace_pos)
> != 1 )
> + if ( IS_ENABLED(CONFIG_VMTRACE) &&
> + hvm_vmtrace_output_position(curr, &req->data.regs.x86.vmtrace_pos)
> != 1 )
Would be nice if the too-long-line issue here was also address, when the line
needs touching anyway.
Jan
