Re: [PATCH v3 21/22] x86/cpu: report SMX, TXT and SKINIT capabilities

[Jan Beulich <jbeulich@xxxxxxxx>]

On 30.05.2025 15:18, Sergii Dmytruk wrote:
> --- a/xen/arch/x86/cpu/amd.c
> +++ b/xen/arch/x86/cpu/amd.c
> @@ -688,6 +688,21 @@ void amd_log_freq(const struct cpuinfo_x86 *c)
>  #undef FREQ
>  }
>  
> +void amd_log_skinit(const struct cpuinfo_x86 *c)
> +{
> +    /*
> +     * Run only on BSP and not during resume to report the capability only 
> once.
> +     */
> +    if ( system_state != SYS_STATE_resume && smp_processor_id() )
> +        return;

Comment and code look to not fit together. DYM

    if ( system_state == SYS_STATE_resume || smp_processor_id() )
        return;

?

> @@ -633,6 +634,49 @@ static void init_intel_perf(struct cpuinfo_x86 *c)
>      }
>  }
>  
> +/*
> + * Print out the SMX and TXT capabilties, so that dom0 can determine if the
> + * system is DRTM-capable.
> + */
> +static void intel_log_smx_txt(void)
> +{
> +    unsigned long cr4_val, getsec_caps;
> +
> +    /*
> +     * Run only on BSP and not during resume to report the capability only 
> once.
> +     */
> +    if ( system_state != SYS_STATE_resume && smp_processor_id() )
> +        return;

Same here?

> +    printk("CPU: SMX capability ");
> +    if ( !test_bit(X86_FEATURE_SMX, &boot_cpu_data.x86_capability) )
> +    {
> +        printk("not supported\n");
> +        return;
> +    }
> +    printk("supported\n");
> +
> +    /* Can't run GETSEC without VMX and SMX */
> +    if ( !test_bit(X86_FEATURE_VMX, &boot_cpu_data.x86_capability) )
> +        return;
> +
> +    cr4_val = read_cr4();
> +    if ( !(cr4_val & X86_CR4_SMXE) )
> +        write_cr4(cr4_val | X86_CR4_SMXE);
> +
> +    asm volatile ("getsec\n"
> +        : "=a" (getsec_caps)
> +        : "a" (GETSEC_CAPABILITIES), "b" (0) :);
> +
> +    if ( getsec_caps & GETSEC_CAP_TXT_CHIPSET )
> +        printk("Chipset supports TXT\n");
> +    else
> +        printk("Chipset does not support TXT\n");
> +
> +    if ( !(cr4_val & X86_CR4_SMXE) )
> +        write_cr4(cr4_val & ~X86_CR4_SMXE);

Move this ahead of the printk()s?

Jan