Re: [PATCH 2/3] x86: add wrapper functions for mtrr functions handling also pat

From: Rafael J. Wysocki
Date: Fri Jul 15 2022 - 12:41:35 EST

On Fri, Jul 15, 2022 at 4:25 PM Juergen Gross <jgross@xxxxxxxx> wrote:
>
> There are several MTRR functions which also do PAT handling. In order
> to support PAT handling without MTRR in the future, add some wrappers
> for those functions.
>
> Cc: <stable@xxxxxxxxxxxxxxx> # 5.17
> Fixes: bdd8b6c98239 ("drm/i915: replace X86_FEATURE_PAT with pat_enabled()")
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>

Do I understand correctly that this particular patch doesn't change
the behavior?

If so, it would be good to mention that in the changelog.

> ---
> arch/x86/include/asm/mtrr.h | 2 --
> arch/x86/include/asm/processor.h | 7 +++++
> arch/x86/kernel/cpu/common.c | 44 +++++++++++++++++++++++++++++++-
> arch/x86/kernel/cpu/mtrr/mtrr.c | 25 +++---------------
> arch/x86/kernel/setup.c | 5 +---
> arch/x86/kernel/smpboot.c | 8 +++---
> arch/x86/power/cpu.c | 2 +-
> 7 files changed, 59 insertions(+), 34 deletions(-)
>
> diff --git a/arch/x86/include/asm/mtrr.h b/arch/x86/include/asm/mtrr.h
> index 12a16caed395..900083ac9f60 100644
> --- a/arch/x86/include/asm/mtrr.h
> +++ b/arch/x86/include/asm/mtrr.h
> @@ -43,7 +43,6 @@ extern int mtrr_del(int reg, unsigned long base, unsigned long size);
> extern int mtrr_del_page(int reg, unsigned long base, unsigned long size);
> extern void mtrr_centaur_report_mcr(int mcr, u32 lo, u32 hi);
> extern void mtrr_ap_init(void);
> -extern void set_mtrr_aps_delayed_init(void);
> extern void mtrr_aps_init(void);
> extern void mtrr_bp_restore(void);
> extern int mtrr_trim_uncached_memory(unsigned long end_pfn);
> @@ -86,7 +85,6 @@ static inline void mtrr_centaur_report_mcr(int mcr, u32 lo, u32 hi)
> {
> }
> #define mtrr_ap_init() do {} while (0)
> -#define set_mtrr_aps_delayed_init() do {} while (0)
> #define mtrr_aps_init() do {} while (0)
> #define mtrr_bp_restore() do {} while (0)
> #define mtrr_disable() do {} while (0)
> diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
> index 5c934b922450..e2140204fb7e 100644
> --- a/arch/x86/include/asm/processor.h
> +++ b/arch/x86/include/asm/processor.h
> @@ -865,7 +865,14 @@ bool arch_is_platform_page(u64 paddr);
> #define arch_is_platform_page arch_is_platform_page
> #endif
>
> +extern bool cache_aps_delayed_init;
> +
> void cache_disable(void);
> void cache_enable(void);
> +void cache_bp_init(void);
> +void cache_ap_init(void);
> +void cache_set_aps_delayed_init(void);
> +void cache_aps_init(void);
> +void cache_bp_restore(void);
>
> #endif /* _ASM_X86_PROCESSOR_H */
> diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
> index e43322f8a4ef..0a1bd14f7966 100644
> --- a/arch/x86/kernel/cpu/common.c
> +++ b/arch/x86/kernel/cpu/common.c
> @@ -1929,7 +1929,7 @@ void identify_secondary_cpu(struct cpuinfo_x86 *c)
> #ifdef CONFIG_X86_32
> enable_sep_cpu();
> #endif
> - mtrr_ap_init();
> + cache_ap_init();
> validate_apic_and_package_id(c);
> x86_spec_ctrl_setup_ap();
> update_srbds_msr();
> @@ -2403,3 +2403,45 @@ void cache_enable(void) __releases(cache_disable_lock)
>
> raw_spin_unlock(&cache_disable_lock);
> }
> +
> +void __init cache_bp_init(void)
> +{
> + if (IS_ENABLED(CONFIG_MTRR))
> + mtrr_bp_init();
> + else
> + pat_disable("PAT support disabled because CONFIG_MTRR is disabled in the kernel.");
> +}
> +
> +void cache_ap_init(void)
> +{
> + if (cache_aps_delayed_init)
> + return;
> +
> + mtrr_ap_init();
> +}
> +
> +bool cache_aps_delayed_init;
> +
> +void cache_set_aps_delayed_init(void)
> +{
> + cache_aps_delayed_init = true;
> +}
> +
> +void cache_aps_init(void)
> +{
> + /*
> + * Check if someone has requested the delay of AP cache initialization,
> + * by doing cache_set_aps_delayed_init(), prior to this point. If not,
> + * then we are done.
> + */
> + if (!cache_aps_delayed_init)
> + return;
> +
> + mtrr_aps_init();
> + cache_aps_delayed_init = false;
> +}
> +
> +void cache_bp_restore(void)
> +{
> + mtrr_bp_restore();
> +}
> diff --git a/arch/x86/kernel/cpu/mtrr/mtrr.c b/arch/x86/kernel/cpu/mtrr/mtrr.c
> index 2746cac9d8a9..c1593cfae641 100644
> --- a/arch/x86/kernel/cpu/mtrr/mtrr.c
> +++ b/arch/x86/kernel/cpu/mtrr/mtrr.c
> @@ -69,7 +69,6 @@ unsigned int mtrr_usage_table[MTRR_MAX_VAR_RANGES];
> static DEFINE_MUTEX(mtrr_mutex);
>
> u64 size_or_mask, size_and_mask;
> -static bool mtrr_aps_delayed_init;
>
> static const struct mtrr_ops *mtrr_ops[X86_VENDOR_NUM] __ro_after_init;
>
> @@ -176,7 +175,8 @@ static int mtrr_rendezvous_handler(void *info)
> if (data->smp_reg != ~0U) {
> mtrr_if->set(data->smp_reg, data->smp_base,
> data->smp_size, data->smp_type);
> - } else if (mtrr_aps_delayed_init || !cpu_online(smp_processor_id())) {
> + } else if ((use_intel() && cache_aps_delayed_init) ||
> + !cpu_online(smp_processor_id())) {
> mtrr_if->set_all();
> }
> return 0;
> @@ -789,7 +789,7 @@ void mtrr_ap_init(void)
> if (!mtrr_enabled())
> return;
>
> - if (!use_intel() || mtrr_aps_delayed_init)
> + if (!use_intel())
> return;
>
> /*
> @@ -823,16 +823,6 @@ void mtrr_save_state(void)
> smp_call_function_single(first_cpu, mtrr_save_fixed_ranges, NULL, 1);
> }
>
> -void set_mtrr_aps_delayed_init(void)
> -{
> - if (!mtrr_enabled())
> - return;
> - if (!use_intel())
> - return;
> -
> - mtrr_aps_delayed_init = true;
> -}
> -
> /*
> * Delayed MTRR initialization for all AP's
> */
> @@ -841,16 +831,7 @@ void mtrr_aps_init(void)
> if (!use_intel() || !mtrr_enabled())
> return;
>
> - /*
> - * Check if someone has requested the delay of AP MTRR initialization,
> - * by doing set_mtrr_aps_delayed_init(), prior to this point. If not,
> - * then we are done.
> - */
> - if (!mtrr_aps_delayed_init)
> - return;
> -
> set_mtrr(~0U, 0, 0, 0);
> - mtrr_aps_delayed_init = false;
> }
>
> void mtrr_bp_restore(void)
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index bd6c6fd373ae..27d61f73c68a 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -1001,10 +1001,7 @@ void __init setup_arch(char **cmdline_p)
> max_pfn = e820__end_of_ram_pfn();
>
> /* update e820 for memory not covered by WB MTRRs */
> - if (IS_ENABLED(CONFIG_MTRR))
> - mtrr_bp_init();
> - else
> - pat_disable("PAT support disabled because CONFIG_MTRR is disabled in the kernel.");
> + cache_bp_init();
>
> if (mtrr_trim_uncached_memory(max_pfn))
> max_pfn = e820__end_of_ram_pfn();
> diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
> index 5e7f9532a10d..535d73a47062 100644
> --- a/arch/x86/kernel/smpboot.c
> +++ b/arch/x86/kernel/smpboot.c
> @@ -1432,7 +1432,7 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus)
>
> uv_system_init();
>
> - set_mtrr_aps_delayed_init();
> + cache_set_aps_delayed_init();
>
> smp_quirk_init_udelay();
>
> @@ -1443,12 +1443,12 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus)
>
> void arch_thaw_secondary_cpus_begin(void)
> {
> - set_mtrr_aps_delayed_init();
> + cache_set_aps_delayed_init();
> }
>
> void arch_thaw_secondary_cpus_end(void)
> {
> - mtrr_aps_init();
> + cache_aps_init();
> }
>
> /*
> @@ -1491,7 +1491,7 @@ void __init native_smp_cpus_done(unsigned int max_cpus)
>
> nmi_selftest();
> impress_friends();
> - mtrr_aps_init();
> + cache_aps_init();
> }
>
> static int __initdata setup_possible_cpus = -1;
> diff --git a/arch/x86/power/cpu.c b/arch/x86/power/cpu.c
> index bb176c72891c..21e014715322 100644
> --- a/arch/x86/power/cpu.c
> +++ b/arch/x86/power/cpu.c
> @@ -261,7 +261,7 @@ static void notrace __restore_processor_state(struct saved_context *ctxt)
> do_fpu_end();
> tsc_verify_tsc_adjust(true);
> x86_platform.restore_sched_clock_state();
> - mtrr_bp_restore();
> + cache_bp_restore();
> perf_restore_debug_store();
>
> c = &cpu_data(smp_processor_id());
> --
> 2.35.3
>