Any comments on this patch? Jimmy
Ren, Qiaowei wrote on 2012-10-11:
> tboot provides a better AP wakeup mechanism based on cpu MWAIT feature
> for OS/VMM. With this mechanism, system will boot faster and will NOT
> require VT to be enabled. But it requires that OS/VMM must have support
> it, otherwise system can never boot up.
>
> Once this mechanism is enabled, tboot will put APs waiting in MWAIT
> loops before launching kernel. kernel can check the new flag field in v6
> tboot shared page for the hint. If the bit TB_FLAG_AP_WAKE_SUPPORT in
> flag field is set, kernel BSP has to write the monitored memory
> (tboot->ap_wake_trigger) to bring APs out of MWAIT loops. The sipi
> vector should be written in tboot->ap_wake_addr before waking up APs.
>
> Signed-off-by: Qiaowei Ren <qiaowei....@intel.com>
> Signed-off-by: Xiaoyan Zhang <xiaoyan.zh...@intel.com>
> Signed-off-by: Gang Wei <gang....@intel.com>
> ---
> arch/x86/kernel/smpboot.c | 21 +++++++++++----------
> arch/x86/kernel/tboot.c | 17 +++++++++++++++++
> include/linux/tboot.h | 17 +++++++++++++++++
> 3 files changed, 45 insertions(+), 10 deletions(-)
> diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
> index c80a33b..884c3e7 100644
> --- a/arch/x86/kernel/smpboot.c
> +++ b/arch/x86/kernel/smpboot.c
> @@ -662,8 +662,7 @@ static int __cpuinit do_boot_cpu(int apicid, int cpu,
> struct task_struct *idle)
> /* start_ip had better be page-aligned! */
> unsigned long start_ip = real_mode_header->trampoline_start;
> - unsigned long boot_error = 0;
> - int timeout;
> + int timeout, boot_error = 0;
>
> /* Just in case we booted with a single CPU. */
> alternatives_enable_smp();
> @@ -710,14 +709,16 @@ static int __cpuinit do_boot_cpu(int apicid, int
cpu,
> struct task_struct *idle)
> }
> }
> - /* - * Kick the secondary CPU. Use the method in the APIC driver
- *
> if it's defined - or use an INIT boot APIC message otherwise: - */
- if
> (apic->wakeup_secondary_cpu) - boot_error =
> apic->wakeup_secondary_cpu(apicid, start_ip); - else -
boot_error =
> wakeup_secondary_cpu_via_init(apicid, start_ip); + if
> (!tboot_wake_up(apicid, start_ip)) { + /* + *
Kick the secondary CPU.
> Use the method in the APIC driver + * if it's defined - or use
an INIT
> boot APIC message otherwise: + */ + if
(apic->wakeup_secondary_cpu)
> + boot_error = apic->wakeup_secondary_cpu(apicid,
start_ip); + else
> + boot_error = wakeup_secondary_cpu_via_init(apicid,
start_ip); + }
>
> if (!boot_error) {
> /*
> diff --git a/arch/x86/kernel/tboot.c b/arch/x86/kernel/tboot.c
> index f84fe00..e5e50b8 100644
> --- a/arch/x86/kernel/tboot.c
> +++ b/arch/x86/kernel/tboot.c
> @@ -101,6 +101,8 @@ void __init tboot_probe(void)
> pr_debug("shutdown_entry: 0x%x\n", tboot->shutdown_entry);
> pr_debug("tboot_base: 0x%08x\n", tboot->tboot_base);
> pr_debug("tboot_size: 0x%x\n", tboot->tboot_size);
> + if (tboot->version >= 6)
> + pr_info("flags: 0x%08x\n", tboot->flags);
> }
>
> static pgd_t *tboot_pg_dir;
> @@ -453,3 +455,18 @@ int tboot_force_iommu(void)
>
> return 1;
> }
> +
> +int tboot_wake_up(int apicid, unsigned long sipi_vec)
> +{
> + if (!tboot_enabled())
> + return 0;
> +
> + if ((tboot->version < 6) ||
> + !(tboot->flags & TB_FLAG_AP_WAKE_SUPPORT))
> + return 0;
> +
> + tboot->ap_wake_addr = sipi_vec;
> + tboot->ap_wake_trigger = apicid;
> +
> + return 1;
> +}
> diff --git a/include/linux/tboot.h b/include/linux/tboot.h
> index c75128b..d65f7e9 100644
> --- a/include/linux/tboot.h
> +++ b/include/linux/tboot.h
> @@ -124,8 +124,23 @@ struct tboot {
>
> /* number of processors in wait-for-SIPI */
> u32 num_in_wfs;
> +
> + /*
> + * version 6+ fields:
> + */
> +
> + u32 flags;
> +
> + /* phys addr of kernel/VMM SIPI vector */
> + u64 ap_wake_addr;
> +
> + /* kernel/VMM writes APIC ID to wake AP */
> + u32 ap_wake_trigger;
> } __packed;
> +/* kernel/VMM use INIT-SIPI-SIPI if clear, ap_wake_* if set */
> +#define TB_FLAG_AP_WAKE_SUPPORT 0X00000001
> +
> /*
> * UUID for tboot data struct to facilitate matching
> * defined as {663C8DFF-E8B3-4b82-AABF-19EA4D057A08} by tboot, which is
> @@ -146,6 +161,7 @@ extern void tboot_shutdown(u32 shutdown_type);
> extern struct acpi_table_header *tboot_get_dmar_table(
> struct acpi_table_header *dmar_tbl);
> extern int tboot_force_iommu(void);
> +extern int tboot_wake_up(int apicid, unsigned long sipi_vec);
>
> #else
> @@ -156,6 +172,7 @@ extern int tboot_force_iommu(void);
> do { } while (0)
> #define tboot_get_dmar_table(dmar_tbl) (dmar_tbl)
> #define tboot_force_iommu() 0
> +#define tboot_wake_up(apicid, sipi_vec) 0
>
> #endif /* !CONFIG_INTEL_TXT */
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