Re: [PATCH v3 1/8] arm64/sysreg: Add definitions for immediate versions of MSR ALLINT

[Liao, Chang]

在 2024/5/4 0:00, Mark Rutland 写道:
> On Mon, Apr 15, 2024 at 06:47:51AM +0000, Liao Chang wrote:
>> From: Mark Brown <broonie@xxxxxxxxxx>
>>
>> Encodings are provided for ALLINT which allow setting of ALLINT.ALLINT
>> using an immediate rather than requiring that a register be loaded with
>> the value to write. Since these don't currently fit within the scheme we
>> have for sysreg generation add manual encodings like we currently do for
>> other similar registers such as SVCR.
>>
>> Since it is required that these immediate versions be encoded with xzr
>> as the source register provide asm wrapper which ensure this is the
>> case.
>>
>> Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
>> Signed-off-by: Liao Chang <liaochang1@xxxxxxxxxx>
>> ---
>>  arch/arm64/include/asm/nmi.h    | 27 +++++++++++++++++++++++++++
>>  arch/arm64/include/asm/sysreg.h |  2 ++
>>  2 files changed, 29 insertions(+)
>>  create mode 100644 arch/arm64/include/asm/nmi.h
> 
> We have helpers for manipulating PSTATE bits; AFAICT we only need the three
> lines below:
> 
> ----8<----
> diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
> index 9e8999592f3af..5c209d07ae57e 100644
> --- a/arch/arm64/include/asm/sysreg.h
> +++ b/arch/arm64/include/asm/sysreg.h
> @@ -94,18 +94,21 @@
>  
>  #define PSTATE_PAN                     pstate_field(0, 4)
>  #define PSTATE_UAO                     pstate_field(0, 3)
> +#define PSTATE_ALLINT                  pstate_field(1, 0)
>  #define PSTATE_SSBS                    pstate_field(3, 1)
>  #define PSTATE_DIT                     pstate_field(3, 2)
>  #define PSTATE_TCO                     pstate_field(3, 4)
>  
>  #define SET_PSTATE_PAN(x)              SET_PSTATE((x), PAN)
>  #define SET_PSTATE_UAO(x)              SET_PSTATE((x), UAO)
> +#define SET_PSTATE_ALLINT(x)           SET_PSTATE((x), ALLINT)
>  #define SET_PSTATE_SSBS(x)             SET_PSTATE((x), SSBS)
>  #define SET_PSTATE_DIT(x)              SET_PSTATE((x), DIT)
>  #define SET_PSTATE_TCO(x)              SET_PSTATE((x), TCO)
>  
>  #define set_pstate_pan(x)              asm volatile(SET_PSTATE_PAN(x))
>  #define set_pstate_uao(x)              asm volatile(SET_PSTATE_UAO(x))
> +#define set_pstate_allint(x)           asm volatile(SET_PSTATE_ALLINT(x))
>  #define set_pstate_ssbs(x)             asm volatile(SET_PSTATE_SSBS(x))
>  #define set_pstate_dit(x)              asm volatile(SET_PSTATE_DIT(x))
> ---->8---- 

Acked, I strongly prefer reusing existing helpers to introducing new ones.

> 
> The addition of <asm/nmi.h> and refrences to <linux/cpumask.h> and
> arm64_supports_nmi() don't seem like they should be part of this patch.

Agree, what about to remove the nmi.h completely in this patch?

Thanks.

> 
> Mark.
> 
>>
>> diff --git a/arch/arm64/include/asm/nmi.h b/arch/arm64/include/asm/nmi.h
>> new file mode 100644
>> index 000000000000..0c566c649485
>> --- /dev/null
>> +++ b/arch/arm64/include/asm/nmi.h
>> @@ -0,0 +1,27 @@
>> +/* SPDX-License-Identifier: GPL-2.0-only */
>> +/*
>> + * Copyright (C) 2022 ARM Ltd.
>> + */
>> +#ifndef __ASM_NMI_H
>> +#define __ASM_NMI_H
>> +
>> +#ifndef __ASSEMBLER__
>> +
>> +#include <linux/cpumask.h>
>> +
>> +extern bool arm64_supports_nmi(void);
>> +
>> +#endif /* !__ASSEMBLER__ */
>> +
>> +static __always_inline void _allint_clear(void)
>> +{
>> +	asm volatile(__msr_s(SYS_ALLINT_CLR, "xzr"));
>> +}
>> +
>> +static __always_inline void _allint_set(void)
>> +{
>> +	asm volatile(__msr_s(SYS_ALLINT_SET, "xzr"));
>> +}
>> +
>> +#endif
>> +
>> diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
>> index 9e8999592f3a..b105773c57ca 100644
>> --- a/arch/arm64/include/asm/sysreg.h
>> +++ b/arch/arm64/include/asm/sysreg.h
>> @@ -167,6 +167,8 @@
>>   * System registers, organised loosely by encoding but grouped together
>>   * where the architected name contains an index. e.g. ID_MMFR<n>_EL1.
>>   */
>> +#define SYS_ALLINT_CLR			sys_reg(0, 1, 4, 0, 0)
>> +#define SYS_ALLINT_SET			sys_reg(0, 1, 4, 1, 0)
>>  #define SYS_SVCR_SMSTOP_SM_EL0		sys_reg(0, 3, 4, 2, 3)
>>  #define SYS_SVCR_SMSTART_SM_EL0		sys_reg(0, 3, 4, 3, 3)
>>  #define SYS_SVCR_SMSTOP_SMZA_EL0	sys_reg(0, 3, 4, 6, 3)
>> -- 
>> 2.34.1
>>

-- 
BR
Liao, Chang