On 2016/12/23 15:04, Ding Tianhong wrote:
> Erratum Hisilicon-161601 says that the ARM generic timer counter "has the
> potential to contain an erroneous value when the timer value changes".
> Accesses to TVAL (both read and write) are also affected due to the implicit counter
> read. Accesses to CVAL are not affected.
>
> The workaround is to reread the system count registers until the value of the second
> read is larger than the first one by less than 32, the system counter can be guaranteed
> not to return wrong value twice by back-to-back read and the error value is always larger
> than the correct one by 32. Writes to TVAL are replaced with an equivalent write to CVAL.
>
> The workaround is enabled if the hisilicon,erratum-161601 property is found in
> the timer node in the device tree. This can be overridden with the
> clocksource.arm_arch_timer.hisilicon-161601 boot parameter, which allows KVM
> users to enable the workaround until a mechanism is implemented to
> automatically communicate this information.
>
> Fix some description for fsl erratum a008585.
>
> v2: Significant rework based on feedback, including seperate the fsl erratum a008585
> to another patch, update the erratum name and remove unwanted code.
>
> v3: Significant rework based on feedback, including fix some alignment problem, make the
> #define __hisi_161601_read_reg to be private to the .c file instead of being globally
> visible, add more accurate annotation and modify a bit of logical format to enable
> arch_timer_read_ool_enabled, remove the kernel commandline parameter
> clocksource.arm_arch_timer.hisilicon-161601.
>
> v5: Theoretically the erratum should not occur more than twice in succession when reading
> the system counter, but it is possible that some interrupts may lead to more than twice
> read errors, triggering the warning, so setting the number of retries to 50 which is far
> beyond the number of iterations the loop has been observed to take.
>
> Signed-off-by: Ding Tianhong <dingtianhong@xxxxxxxxxx>
> ---
> Documentation/arm64/silicon-errata.txt | 1 +
> arch/arm64/include/asm/arch_timer.h | 2 +-
> drivers/clocksource/Kconfig | 9 +++++
> drivers/clocksource/arm_arch_timer.c | 70 +++++++++++++++++++++++++++++++---
> 4 files changed, 76 insertions(+), 6 deletions(-)
>
> diff --git a/Documentation/arm64/silicon-errata.txt b/Documentation/arm64/silicon-errata.txt
> index 405da11..1c1a95f 100644
> --- a/Documentation/arm64/silicon-errata.txt
> +++ b/Documentation/arm64/silicon-errata.txt
> @@ -63,3 +63,4 @@ stable kernels.
> | Cavium | ThunderX SMMUv2 | #27704 | N/A |
> | | | | |
> | Freescale/NXP | LS2080A/LS1043A | A-008585 | FSL_ERRATUM_A008585 |
> +| Hisilicon | Hip0{5,6,7} | #161601 | HISILICON_ERRATUM_161601|
> diff --git a/arch/arm64/include/asm/arch_timer.h b/arch/arm64/include/asm/arch_timer.h
> index f882c7c..ebf4cde 100644
> --- a/arch/arm64/include/asm/arch_timer.h
> +++ b/arch/arm64/include/asm/arch_timer.h
> @@ -29,7 +29,7 @@
>
> #include <clocksource/arm_arch_timer.h>
>
> -#if IS_ENABLED(CONFIG_FSL_ERRATUM_A008585)
> +#if IS_ENABLED(CONFIG_FSL_ERRATUM_A008585) || IS_ENABLED(CONFIG_HISILICON_ERRATUM_161601)
> extern struct static_key_false arch_timer_read_ool_enabled;
> #define needs_unstable_timer_counter_workaround() \
> static_branch_unlikely(&arch_timer_read_ool_enabled)
> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
> index 4866f7a..162d820 100644
> --- a/drivers/clocksource/Kconfig
> +++ b/drivers/clocksource/Kconfig
> @@ -335,6 +335,15 @@ config FSL_ERRATUM_A008585
> value"). The workaround will only be active if the
> fsl,erratum-a008585 property is found in the timer node.
>
> +config HISILICON_ERRATUM_161601
> + bool "Workaround for Hisilicon Erratum 161601"
> + default y
> + depends on ARM_ARCH_TIMER && ARM64
> + help
> + This option enables a workaround for Hisilicon Erratum
> + 161601. The workaround will be active if the hisilicon,erratum-161601
> + property is found in the timer node.
> +
> config ARM_GLOBAL_TIMER
> bool "Support for the ARM global timer" if COMPILE_TEST
> select CLKSRC_OF if OF
> diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
> index e7406ad..9a82496 100644
> --- a/drivers/clocksource/arm_arch_timer.c
> +++ b/drivers/clocksource/arm_arch_timer.c
> @@ -95,15 +95,18 @@ static int __init early_evtstrm_cfg(char *buf)
> * Architected system timer support.
> */
>
> -#ifdef CONFIG_FSL_ERRATUM_A008585
> +#if CONFIG_FSL_ERRATUM_A008585 || IS_ENABLED(CONFIG_HISILICON_ERRATUM_161601)
> struct arch_timer_erratum_workaround *timer_unstable_counter_workaround = NULL;
> EXPORT_SYMBOL_GPL(timer_unstable_counter_workaround);
>
> #define FSL_A008585 0x0001
> +#define HISILICON_161601 0x0002
It looks like the DEFINE is useless，
> +
> +static struct arch_timer_erratum_workaround arch_timer_hisi_161601 = {
> + .erratum = HISILICON_161601,
Just a errata description, eg.
.desc = "HISILICON ERRATUM 161601"
then....
> + .read_cntp_tval_el0 = hisi_161601_read_cntp_tval_el0,
> + .read_cntv_tval_el0 = hisi_161601_read_cntv_tval_el0,
> + .read_cntvct_el0 = hisi_161601_read_cntvct_el0,
> +};
> +#endif /* CONFIG_HISILICON_ERRATUM_161601 */
[..]
> -#ifdef CONFIG_FSL_ERRATUM_A008585
> +#if IS_ENABLED(CONFIG_FSL_ERRATUM_A008585) || IS_ENABLED(CONFIG_HISILICON_ERRATUM_161601)
> /*
> * Don't use the vdso fastpath if errata require using
> * the out-of-line counter accessor.
> @@ -909,10 +960,19 @@ static int __init arch_timer_of_init(struct device_node *np)
> #ifdef CONFIG_FSL_ERRATUM_A008585
> if (!timer_unstable_counter_workaround && of_property_read_bool(np, "fsl,erratum-a008585"))
> timer_unstable_counter_workaround = &arch_timer_fsl_a008585;
> +#endif
> +
> +#ifdef CONFIG_HISILICON_ERRATUM_161601
> + if (!timer_unstable_counter_workaround && of_property_read_bool(np, "hisilicon,erratum-161601"))
> + timer_unstable_counter_workaround = &arch_timer_hisi_161601;
> +#endif
>
> +#if IS_ENABLED(CONFIG_FSL_ERRATUM_A008585) || IS_ENABLED(CONFIG_HISILICON_ERRATUM_161601)
> if (timer_unstable_counter_workaround) {
> static_branch_enable(&arch_timer_read_ool_enabled);
> - pr_info("Enabling workaround for FSL erratum A-008585\n");
> + pr_info("Enabling workaround for %s\n",
> + timer_unstable_counter_workaround->erratum == FSL_A008585 ?
> + "FSL ERRATUM A-008585" : "HISILICON ERRATUM 161601");
......> pr_info("Enabling workaround for %s\n", timer_unstable_counter_workaround->desc)
> }
> #endif
>
>
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