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Message-ID: <alpine.DEB.2.22.394.2507161749090.15546@ubuntu-linux-20-04-desktop>
Date: Wed, 16 Jul 2025 17:49:22 -0700 (PDT)
From: Stefano Stabellini <sstabellini@...nel.org>
To: Ard Biesheuvel <ardb+git@...gle.com>
cc: linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
Ard Biesheuvel <ardb@...nel.org>,
Heinrich Schuchardt <heinrich.schuchardt@...onical.com>,
Feng Tang <feng.tang@...ux.alibaba.com>,
Alexandre Belloni <alexandre.belloni@...tlin.com>,
Juergen Gross <jgross@...e.com>,
Stefano Stabellini <sstabellini@...nel.org>,
Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>,
Sunil V L <sunilvl@...tanamicro.com>, Bibo Mao <maobibo@...ngson.cn>,
linux-rtc@...r.kernel.org, linux-efi@...r.kernel.org,
xen-devel@...ts.xenproject.org, x86@...nel.org,
linux-riscv@...ts.infradead.org, loongarch@...ts.linux.dev
Subject: Re: [RFC PATCH 3/3] efi: Remove support for pointless, unused EFI
services
On Mon, 14 Jul 2025, Ard Biesheuvel wrote:
> From: Ard Biesheuvel <ardb@...nel.org>
>
> The get/set wakeup time EFI runtime services are often broken, and
> rarely if ever used in practice. But the GetNextHighMonoCount() EFI
> runtime services really takes the cake for most pointless API in the
> history of computing.
>
> So let's stop exposing them in Linux, hopefully removing the urge some
> folks seem to feel to test these APIs, and send emails around when they
> don't work.
>
> Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
For drivers/xen/efi.c:
Acked-by: Stefano Stabellini <sstabellini@...nel.org>
> ---
> arch/x86/platform/efi/efi_64.c | 22 -------
> drivers/firmware/efi/runtime-wrappers.c | 68 --------------------
> drivers/xen/efi.c | 56 ----------------
> include/linux/efi.h | 6 --
> 4 files changed, 152 deletions(-)
>
> diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
> index e7e8f77f77f8..0207937ab39d 100644
> --- a/arch/x86/platform/efi/efi_64.c
> +++ b/arch/x86/platform/efi/efi_64.c
> @@ -540,19 +540,6 @@ static efi_status_t efi_thunk_set_time(efi_time_t *tm)
> return EFI_UNSUPPORTED;
> }
>
> -static efi_status_t
> -efi_thunk_get_wakeup_time(efi_bool_t *enabled, efi_bool_t *pending,
> - efi_time_t *tm)
> -{
> - return EFI_UNSUPPORTED;
> -}
> -
> -static efi_status_t
> -efi_thunk_set_wakeup_time(efi_bool_t enabled, efi_time_t *tm)
> -{
> - return EFI_UNSUPPORTED;
> -}
> -
> static unsigned long efi_name_size(efi_char16_t *name)
> {
> return ucs2_strsize(name, EFI_VAR_NAME_LEN) + 1;
> @@ -681,12 +668,6 @@ efi_thunk_get_next_variable(unsigned long *name_size,
> return status;
> }
>
> -static efi_status_t
> -efi_thunk_get_next_high_mono_count(u32 *count)
> -{
> - return EFI_UNSUPPORTED;
> -}
> -
> static void
> efi_thunk_reset_system(int reset_type, efi_status_t status,
> unsigned long data_size, efi_char16_t *data)
> @@ -788,13 +769,10 @@ void __init efi_thunk_runtime_setup(void)
>
> efi.get_time = efi_thunk_get_time;
> efi.set_time = efi_thunk_set_time;
> - efi.get_wakeup_time = efi_thunk_get_wakeup_time;
> - efi.set_wakeup_time = efi_thunk_set_wakeup_time;
> efi.get_variable = efi_thunk_get_variable;
> efi.get_next_variable = efi_thunk_get_next_variable;
> efi.set_variable = efi_thunk_set_variable;
> efi.set_variable_nonblocking = efi_thunk_set_variable_nonblocking;
> - efi.get_next_high_mono_count = efi_thunk_get_next_high_mono_count;
> efi.reset_system = efi_thunk_reset_system;
> efi.query_variable_info = efi_thunk_query_variable_info;
> efi.query_variable_info_nonblocking = efi_thunk_query_variable_info_nonblocking;
> diff --git a/drivers/firmware/efi/runtime-wrappers.c b/drivers/firmware/efi/runtime-wrappers.c
> index 708b777857d3..2b66efb5ffef 100644
> --- a/drivers/firmware/efi/runtime-wrappers.c
> +++ b/drivers/firmware/efi/runtime-wrappers.c
> @@ -52,17 +52,6 @@ union efi_rts_args {
> efi_time_t *time;
> } SET_TIME;
>
> - struct {
> - efi_bool_t *enabled;
> - efi_bool_t *pending;
> - efi_time_t *time;
> - } GET_WAKEUP_TIME;
> -
> - struct {
> - efi_bool_t enable;
> - efi_time_t *time;
> - } SET_WAKEUP_TIME;
> -
> struct {
> efi_char16_t *name;
> efi_guid_t *vendor;
> @@ -92,10 +81,6 @@ union efi_rts_args {
> u64 *max_variable_size;
> } QUERY_VARIABLE_INFO;
>
> - struct {
> - u32 *high_count;
> - } GET_NEXT_HIGH_MONO_COUNT;
> -
> struct {
> efi_capsule_header_t **capsules;
> unsigned long count;
> @@ -232,17 +217,6 @@ static void __nocfi efi_call_rts(struct work_struct *work)
> status = efi_call_virt(set_time,
> args->SET_TIME.time);
> break;
> - case EFI_GET_WAKEUP_TIME:
> - status = efi_call_virt(get_wakeup_time,
> - args->GET_WAKEUP_TIME.enabled,
> - args->GET_WAKEUP_TIME.pending,
> - args->GET_WAKEUP_TIME.time);
> - break;
> - case EFI_SET_WAKEUP_TIME:
> - status = efi_call_virt(set_wakeup_time,
> - args->SET_WAKEUP_TIME.enable,
> - args->SET_WAKEUP_TIME.time);
> - break;
> case EFI_GET_VARIABLE:
> status = efi_call_virt(get_variable,
> args->GET_VARIABLE.name,
> @@ -272,10 +246,6 @@ static void __nocfi efi_call_rts(struct work_struct *work)
> args->QUERY_VARIABLE_INFO.remaining_space,
> args->QUERY_VARIABLE_INFO.max_variable_size);
> break;
> - case EFI_GET_NEXT_HIGH_MONO_COUNT:
> - status = efi_call_virt(get_next_high_mono_count,
> - args->GET_NEXT_HIGH_MONO_COUNT.high_count);
> - break;
> case EFI_UPDATE_CAPSULE:
> status = efi_call_virt(update_capsule,
> args->UPDATE_CAPSULE.capsules,
> @@ -366,30 +336,6 @@ static efi_status_t virt_efi_set_time(efi_time_t *tm)
> return status;
> }
>
> -static efi_status_t virt_efi_get_wakeup_time(efi_bool_t *enabled,
> - efi_bool_t *pending,
> - efi_time_t *tm)
> -{
> - efi_status_t status;
> -
> - if (down_interruptible(&efi_runtime_lock))
> - return EFI_ABORTED;
> - status = efi_queue_work(GET_WAKEUP_TIME, enabled, pending, tm);
> - up(&efi_runtime_lock);
> - return status;
> -}
> -
> -static efi_status_t virt_efi_set_wakeup_time(efi_bool_t enabled, efi_time_t *tm)
> -{
> - efi_status_t status;
> -
> - if (down_interruptible(&efi_runtime_lock))
> - return EFI_ABORTED;
> - status = efi_queue_work(SET_WAKEUP_TIME, enabled, tm);
> - up(&efi_runtime_lock);
> - return status;
> -}
> -
> static efi_status_t virt_efi_get_variable(efi_char16_t *name,
> efi_guid_t *vendor,
> u32 *attr,
> @@ -488,17 +434,6 @@ virt_efi_query_variable_info_nb(u32 attr, u64 *storage_space,
> return status;
> }
>
> -static efi_status_t virt_efi_get_next_high_mono_count(u32 *count)
> -{
> - efi_status_t status;
> -
> - if (down_interruptible(&efi_runtime_lock))
> - return EFI_ABORTED;
> - status = efi_queue_work(GET_NEXT_HIGH_MONO_COUNT, count);
> - up(&efi_runtime_lock);
> - return status;
> -}
> -
> static void __nocfi
> virt_efi_reset_system(int reset_type, efi_status_t status,
> unsigned long data_size, efi_char16_t *data)
> @@ -556,13 +491,10 @@ void __init efi_native_runtime_setup(void)
> {
> efi.get_time = virt_efi_get_time;
> efi.set_time = virt_efi_set_time;
> - efi.get_wakeup_time = virt_efi_get_wakeup_time;
> - efi.set_wakeup_time = virt_efi_set_wakeup_time;
> efi.get_variable = virt_efi_get_variable;
> efi.get_next_variable = virt_efi_get_next_variable;
> efi.set_variable = virt_efi_set_variable;
> efi.set_variable_nonblocking = virt_efi_set_variable_nb;
> - efi.get_next_high_mono_count = virt_efi_get_next_high_mono_count;
> efi.reset_system = virt_efi_reset_system;
> efi.query_variable_info = virt_efi_query_variable_info;
> efi.query_variable_info_nonblocking = virt_efi_query_variable_info_nb;
> diff --git a/drivers/xen/efi.c b/drivers/xen/efi.c
> index fb321cd6415a..baccf2d90af0 100644
> --- a/drivers/xen/efi.c
> +++ b/drivers/xen/efi.c
> @@ -76,47 +76,6 @@ static efi_status_t xen_efi_set_time(efi_time_t *tm)
> return efi_data(op).status;
> }
>
> -static efi_status_t xen_efi_get_wakeup_time(efi_bool_t *enabled,
> - efi_bool_t *pending,
> - efi_time_t *tm)
> -{
> - struct xen_platform_op op = INIT_EFI_OP(get_wakeup_time);
> -
> - if (HYPERVISOR_platform_op(&op) < 0)
> - return EFI_UNSUPPORTED;
> -
> - if (tm) {
> - BUILD_BUG_ON(sizeof(*tm) != sizeof(efi_data(op).u.get_wakeup_time));
> - memcpy(tm, &efi_data(op).u.get_wakeup_time, sizeof(*tm));
> - }
> -
> - if (enabled)
> - *enabled = !!(efi_data(op).misc & XEN_EFI_GET_WAKEUP_TIME_ENABLED);
> -
> - if (pending)
> - *pending = !!(efi_data(op).misc & XEN_EFI_GET_WAKEUP_TIME_PENDING);
> -
> - return efi_data(op).status;
> -}
> -
> -static efi_status_t xen_efi_set_wakeup_time(efi_bool_t enabled, efi_time_t *tm)
> -{
> - struct xen_platform_op op = INIT_EFI_OP(set_wakeup_time);
> -
> - BUILD_BUG_ON(sizeof(*tm) != sizeof(efi_data(op).u.set_wakeup_time));
> - if (enabled)
> - efi_data(op).misc = XEN_EFI_SET_WAKEUP_TIME_ENABLE;
> - if (tm)
> - memcpy(&efi_data(op).u.set_wakeup_time, tm, sizeof(*tm));
> - else
> - efi_data(op).misc |= XEN_EFI_SET_WAKEUP_TIME_ENABLE_ONLY;
> -
> - if (HYPERVISOR_platform_op(&op) < 0)
> - return EFI_UNSUPPORTED;
> -
> - return efi_data(op).status;
> -}
> -
> static efi_status_t xen_efi_get_variable(efi_char16_t *name, efi_guid_t *vendor,
> u32 *attr, unsigned long *data_size,
> void *data)
> @@ -204,18 +163,6 @@ static efi_status_t xen_efi_query_variable_info(u32 attr, u64 *storage_space,
> return efi_data(op).status;
> }
>
> -static efi_status_t xen_efi_get_next_high_mono_count(u32 *count)
> -{
> - struct xen_platform_op op = INIT_EFI_OP(get_next_high_monotonic_count);
> -
> - if (HYPERVISOR_platform_op(&op) < 0)
> - return EFI_UNSUPPORTED;
> -
> - *count = efi_data(op).misc;
> -
> - return efi_data(op).status;
> -}
> -
> static efi_status_t xen_efi_update_capsule(efi_capsule_header_t **capsules,
> unsigned long count, unsigned long sg_list)
> {
> @@ -280,8 +227,6 @@ void __init xen_efi_runtime_setup(void)
> {
> efi.get_time = xen_efi_get_time;
> efi.set_time = xen_efi_set_time;
> - efi.get_wakeup_time = xen_efi_get_wakeup_time;
> - efi.set_wakeup_time = xen_efi_set_wakeup_time;
> efi.get_variable = xen_efi_get_variable;
> efi.get_next_variable = xen_efi_get_next_variable;
> efi.set_variable = xen_efi_set_variable;
> @@ -290,7 +235,6 @@ void __init xen_efi_runtime_setup(void)
> efi.query_variable_info_nonblocking = xen_efi_query_variable_info;
> efi.update_capsule = xen_efi_update_capsule;
> efi.query_capsule_caps = xen_efi_query_capsule_caps;
> - efi.get_next_high_mono_count = xen_efi_get_next_high_mono_count;
> efi.reset_system = xen_efi_reset_system;
> }
>
> diff --git a/include/linux/efi.h b/include/linux/efi.h
> index 50db7df0efab..516afdc8a49d 100644
> --- a/include/linux/efi.h
> +++ b/include/linux/efi.h
> @@ -650,8 +650,6 @@ extern struct efi {
>
> efi_get_time_t *get_time;
> efi_set_time_t *set_time;
> - efi_get_wakeup_time_t *get_wakeup_time;
> - efi_set_wakeup_time_t *set_wakeup_time;
> efi_get_variable_t *get_variable;
> efi_get_next_variable_t *get_next_variable;
> efi_set_variable_t *set_variable;
> @@ -660,7 +658,6 @@ extern struct efi {
> efi_query_variable_info_t *query_variable_info_nonblocking;
> efi_update_capsule_t *update_capsule;
> efi_query_capsule_caps_t *query_capsule_caps;
> - efi_get_next_high_mono_count_t *get_next_high_mono_count;
> efi_reset_system_t *reset_system;
>
> struct efi_memory_map memmap;
> @@ -1235,13 +1232,10 @@ enum efi_rts_ids {
> EFI_NONE,
> EFI_GET_TIME,
> EFI_SET_TIME,
> - EFI_GET_WAKEUP_TIME,
> - EFI_SET_WAKEUP_TIME,
> EFI_GET_VARIABLE,
> EFI_GET_NEXT_VARIABLE,
> EFI_SET_VARIABLE,
> EFI_QUERY_VARIABLE_INFO,
> - EFI_GET_NEXT_HIGH_MONO_COUNT,
> EFI_RESET_SYSTEM,
> EFI_UPDATE_CAPSULE,
> EFI_QUERY_CAPSULE_CAPS,
> --
> 2.50.0.727.gbf7dc18ff4-goog
>
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