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Re: [PATCH v3 1/7] xen/arm: Add ID registers and complete cpuinfo


  • To: Julien Grall <julien@xxxxxxx>
  • From: Bertrand Marquis <Bertrand.Marquis@xxxxxxx>
  • Date: Thu, 10 Dec 2020 15:58:10 +0000
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  • Thread-topic: [PATCH v3 1/7] xen/arm: Add ID registers and complete cpuinfo

Hi,

> On 10 Dec 2020, at 15:45, Julien Grall <julien@xxxxxxx> wrote:
> 
> Hi Bertrand,
> 
> On 10/12/2020 15:14, Bertrand Marquis wrote:
>> Hi Julien,
>>> On 9 Dec 2020, at 23:03, Julien Grall <julien@xxxxxxx> wrote:
>>> 
>>> Hi Bertrand,
>>> 
>>> On 09/12/2020 16:30, Bertrand Marquis wrote:
>>>> Add definition and entries in cpuinfo for ID registers introduced in
>>>> newer Arm Architecture reference manual:
>>>> - ID_PFR2: processor feature register 2
>>>> - ID_DFR1: debug feature register 1
>>>> - ID_MMFR4 and ID_MMFR5: Memory model feature registers 4 and 5
>>>> - ID_ISA6: ISA Feature register 6
>>>> Add more bitfield definitions in PFR fields of cpuinfo.
>>>> Add MVFR2 register definition for aarch32.
>>>> Add mvfr values in cpuinfo.
>>>> Add some registers definition for arm64 in sysregs as some are not
>>>> always know by compilers.
>>>> Initialize the new values added in cpuinfo in identify_cpu during init.
>>>> Signed-off-by: Bertrand Marquis <bertrand.marquis@xxxxxxx>
>>>> ---
>>>> Changes in V2:
>>>>   Fix dbg32 table size and add proper initialisation of the second entry
>>>>   of the table by reading ID_DFR1 register.
>>>> Changes in V3:
>>>>   Fix typo in commit title
>>>>   Add MVFR2 definition and handling on aarch32 and remove specific case
>>>>   for mvfr field in cpuinfo (now the same on arm64 and arm32).
>>>>   Add MMFR4 definition if not known by the compiler.
>>>> ---
>>>>  xen/arch/arm/cpufeature.c           | 18 ++++++++++
>>>>  xen/include/asm-arm/arm64/sysregs.h | 28 +++++++++++++++
>>>>  xen/include/asm-arm/cpregs.h        | 12 +++++++
>>>>  xen/include/asm-arm/cpufeature.h    | 56 ++++++++++++++++++++++++-----
>>>>  4 files changed, 105 insertions(+), 9 deletions(-)
>>>> diff --git a/xen/arch/arm/cpufeature.c b/xen/arch/arm/cpufeature.c
>>>> index 44126dbf07..bc7ee5ac95 100644
>>>> --- a/xen/arch/arm/cpufeature.c
>>>> +++ b/xen/arch/arm/cpufeature.c
>>>> @@ -114,15 +114,20 @@ void identify_cpu(struct cpuinfo_arm *c)
>>>>            c->mm64.bits[0]  = READ_SYSREG64(ID_AA64MMFR0_EL1);
>>>>          c->mm64.bits[1]  = READ_SYSREG64(ID_AA64MMFR1_EL1);
>>>> +        c->mm64.bits[2]  = READ_SYSREG64(ID_AA64MMFR2_EL1);
>>>>            c->isa64.bits[0] = READ_SYSREG64(ID_AA64ISAR0_EL1);
>>>>          c->isa64.bits[1] = READ_SYSREG64(ID_AA64ISAR1_EL1);
>>>> +
>>>> +        c->zfr64.bits[0] = READ_SYSREG64(ID_AA64ZFR0_EL1);
>>>>  #endif
>>>>            c->pfr32.bits[0] = READ_SYSREG32(ID_PFR0_EL1);
>>>>          c->pfr32.bits[1] = READ_SYSREG32(ID_PFR1_EL1);
>>>> +        c->pfr32.bits[2] = READ_SYSREG32(ID_PFR2_EL1);
>>>>            c->dbg32.bits[0] = READ_SYSREG32(ID_DFR0_EL1);
>>>> +        c->dbg32.bits[1] = READ_SYSREG32(ID_DFR1_EL1);
>>>>            c->aux32.bits[0] = READ_SYSREG32(ID_AFR0_EL1);
>>>>  @@ -130,6 +135,8 @@ void identify_cpu(struct cpuinfo_arm *c)
>>>>          c->mm32.bits[1]  = READ_SYSREG32(ID_MMFR1_EL1);
>>>>          c->mm32.bits[2]  = READ_SYSREG32(ID_MMFR2_EL1);
>>>>          c->mm32.bits[3]  = READ_SYSREG32(ID_MMFR3_EL1);
>>>> +        c->mm32.bits[4]  = READ_SYSREG32(ID_MMFR4_EL1);
>>>> +        c->mm32.bits[5]  = READ_SYSREG32(ID_MMFR5_EL1);
>>> 
>>> Please don't introduce any more use of READ_SYSREG32(), they are wrong on 
>>> Armv8 because system registers are always 64-bit.
>> I followed the existing implementation but ...
>>> 
>>>>            c->isa32.bits[0] = READ_SYSREG32(ID_ISAR0_EL1);
>>>>          c->isa32.bits[1] = READ_SYSREG32(ID_ISAR1_EL1);
>>>> @@ -137,6 +144,17 @@ void identify_cpu(struct cpuinfo_arm *c)
>>>>          c->isa32.bits[3] = READ_SYSREG32(ID_ISAR3_EL1);
>>>>          c->isa32.bits[4] = READ_SYSREG32(ID_ISAR4_EL1);
>>>>          c->isa32.bits[5] = READ_SYSREG32(ID_ISAR5_EL1);
>>>> +        c->isa32.bits[6] = READ_SYSREG32(ID_ISAR6_EL1);
>>>> +
>>>> +#ifdef CONFIG_ARM_64
>>>> +        c->mvfr.bits[0] = READ_SYSREG64(MVFR0_EL1);
>>>> +        c->mvfr.bits[1] = READ_SYSREG64(MVFR1_EL1);
>>>> +        c->mvfr.bits[2] = READ_SYSREG64(MVFR2_EL1);
>>>> +#else
>>>> +        c->mvfr.bits[0] = READ_CP32(MVFR0);
>>>> +        c->mvfr.bits[1] = READ_CP32(MVFR1);
>>>> +        c->mvfr.bits[2] = READ_CP32(MVFR2);
>>>> +#endif
>>> 
>>> READ_SYSREG() will do the job to either use READ_SYSREG64() or READ_CP32() 
>>> depending on the arch used.
>> .. I can modify the ones I added and the existing ones to user READ_SYSREG 
>> instead.
>> Please confirm if you want me to do that.
> 
> Yes, please use READ_SYSREG() for the new ones. We can convert the others 
> separately.
> 
>>> 
>>>>  }
>>>>    /*
>>>> diff --git a/xen/include/asm-arm/arm64/sysregs.h 
>>>> b/xen/include/asm-arm/arm64/sysregs.h
>>>> index c60029d38f..077fd95fb7 100644
>>>> --- a/xen/include/asm-arm/arm64/sysregs.h
>>>> +++ b/xen/include/asm-arm/arm64/sysregs.h
>>>> @@ -57,6 +57,34 @@
>>>>  #define ICH_AP1R2_EL2             __AP1Rx_EL2(2)
>>>>  #define ICH_AP1R3_EL2             __AP1Rx_EL2(3)
>>>>  +/*
>>>> + * Define ID coprocessor registers if they are not
>>>> + * already defined by the compiler.
>>>> + *
>>>> + * Values picked from linux kernel
>>>> + */
>>>> +#ifndef ID_AA64MMFR2_EL1
>>> 
>>> I am a bit puzzled how this meant to work. Will the libc/compiler headers 
>>> define ID_AA64MMFR2_EL1?
>> I tested this and if the compiler has a definition for the register, I am 
>> not entering the ifndef.
>> So there is no header defining this but if the compiler has the definition 
>> for this the ifndef will
>> not be entered.
> 
> Good to hear :).
> 
>>> 
>>>> +#define ID_AA64MMFR2_EL1            S3_0_C0_C7_2
>>>> +#endif
>>>> +#ifndef ID_PFR2_EL1
>>>> +#define ID_PFR2_EL1                 S3_0_C0_C3_4
>>>> +#endif
>>>> +#ifndef ID_MMFR4_EL1
>>>> +#define ID_MMFR4_EL1                S3_0_C0_C2_6
>>>> +#endif
>>>> +#ifndef ID_MMFR5_EL1
>>>> +#define ID_MMFR5_EL1                S3_0_C0_C3_6
>>>> +#endif
>>>> +#ifndef ID_ISAR6_EL1
>>>> +#define ID_ISAR6_EL1                S3_0_C0_C2_7
>>>> +#endif
>>>> +#ifndef ID_AA64ZFR0_EL1
>>>> +#define ID_AA64ZFR0_EL1             S3_0_C0_C4_4
>>>> +#endif
>>>> +#ifndef ID_DFR1_EL1
>>>> +#define ID_DFR1_EL1                 S3_0_C0_C3_5
>>>> +#endif
>>>> +
>>>>  /* Access to system registers */
>>>>    #define READ_SYSREG32(name) ((uint32_t)READ_SYSREG64(name))
>>>> diff --git a/xen/include/asm-arm/cpregs.h b/xen/include/asm-arm/cpregs.h
>>>> index 8fd344146e..2690ddeb7a 100644
>>>> --- a/xen/include/asm-arm/cpregs.h
>>>> +++ b/xen/include/asm-arm/cpregs.h
>>>> @@ -63,6 +63,8 @@
>>>>  #define FPSID           p10,7,c0,c0,0   /* Floating-Point System ID 
>>>> Register */
>>>>  #define FPSCR           p10,7,c1,c0,0   /* Floating-Point Status and 
>>>> Control Register */
>>>>  #define MVFR0           p10,7,c7,c0,0   /* Media and VFP Feature Register 
>>>> 0 */
>>>> +#define MVFR1           p10,7,c6,c0,0   /* Media and VFP Feature Register 
>>>> 1 */
>>>> +#define MVFR2           p10,7,c5,c0,0   /* Media and VFP Feature Register 
>>>> 2 */
>>>>  #define FPEXC           p10,7,c8,c0,0   /* Floating-Point Exception 
>>>> Control Register */
>>>>  #define FPINST          p10,7,c9,c0,0   /* Floating-Point Instruction 
>>>> Register */
>>>>  #define FPINST2         p10,7,c10,c0,0  /* Floating-point Instruction 
>>>> Register 2 */
>>>> @@ -108,18 +110,23 @@
>>>>  #define MPIDR           p15,0,c0,c0,5   /* Multiprocessor Affinity 
>>>> Register */
>>>>  #define ID_PFR0         p15,0,c0,c1,0   /* Processor Feature Register 0 */
>>>>  #define ID_PFR1         p15,0,c0,c1,1   /* Processor Feature Register 1 */
>>>> +#define ID_PFR2         p15,0,c0,c3,4   /* Processor Feature Register 2 */
>>>>  #define ID_DFR0         p15,0,c0,c1,2   /* Debug Feature Register 0 */
>>>> +#define ID_DFR1         p15,0,c0,c3,5   /* Debug Feature Register 1 */
>>>>  #define ID_AFR0         p15,0,c0,c1,3   /* Auxiliary Feature Register 0 */
>>>>  #define ID_MMFR0        p15,0,c0,c1,4   /* Memory Model Feature Register 
>>>> 0 */
>>>>  #define ID_MMFR1        p15,0,c0,c1,5   /* Memory Model Feature Register 
>>>> 1 */
>>>>  #define ID_MMFR2        p15,0,c0,c1,6   /* Memory Model Feature Register 
>>>> 2 */
>>>>  #define ID_MMFR3        p15,0,c0,c1,7   /* Memory Model Feature Register 
>>>> 3 */
>>>> +#define ID_MMFR4        p15,0,c0,c2,6   /* Memory Model Feature Register 
>>>> 4 */
>>>> +#define ID_MMFR5        p15,0,c0,c3,6   /* Memory Model Feature Register 
>>>> 5 */
>>>>  #define ID_ISAR0        p15,0,c0,c2,0   /* ISA Feature Register 0 */
>>>>  #define ID_ISAR1        p15,0,c0,c2,1   /* ISA Feature Register 1 */
>>>>  #define ID_ISAR2        p15,0,c0,c2,2   /* ISA Feature Register 2 */
>>>>  #define ID_ISAR3        p15,0,c0,c2,3   /* ISA Feature Register 3 */
>>>>  #define ID_ISAR4        p15,0,c0,c2,4   /* ISA Feature Register 4 */
>>>>  #define ID_ISAR5        p15,0,c0,c2,5   /* ISA Feature Register 5 */
>>>> +#define ID_ISAR6        p15,0,c0,c2,7   /* ISA Feature Register 6 */
>>>>  #define CCSIDR          p15,1,c0,c0,0   /* Cache Size ID Registers */
>>>>  #define CLIDR           p15,1,c0,c0,1   /* Cache Level ID Register */
>>>>  #define CSSELR          p15,2,c0,c0,0   /* Cache Size Selection Register 
>>>> */
>>>> @@ -312,18 +319,23 @@
>>>>  #define HSTR_EL2                HSTR
>>>>  #define ID_AFR0_EL1             ID_AFR0
>>>>  #define ID_DFR0_EL1             ID_DFR0
>>>> +#define ID_DFR1_EL1             ID_DFR1
>>>>  #define ID_ISAR0_EL1            ID_ISAR0
>>>>  #define ID_ISAR1_EL1            ID_ISAR1
>>>>  #define ID_ISAR2_EL1            ID_ISAR2
>>>>  #define ID_ISAR3_EL1            ID_ISAR3
>>>>  #define ID_ISAR4_EL1            ID_ISAR4
>>>>  #define ID_ISAR5_EL1            ID_ISAR5
>>>> +#define ID_ISAR6_EL1            ID_ISAR6
>>>>  #define ID_MMFR0_EL1            ID_MMFR0
>>>>  #define ID_MMFR1_EL1            ID_MMFR1
>>>>  #define ID_MMFR2_EL1            ID_MMFR2
>>>>  #define ID_MMFR3_EL1            ID_MMFR3
>>>> +#define ID_MMFR4_EL1            ID_MMFR4
>>>> +#define ID_MMFR5_EL1            ID_MMFR5
>>>>  #define ID_PFR0_EL1             ID_PFR0
>>>>  #define ID_PFR1_EL1             ID_PFR1
>>>> +#define ID_PFR2_EL1             ID_PFR2
>>>>  #define IFSR32_EL2              IFSR
>>>>  #define MDCR_EL2                HDCR
>>>>  #define MIDR_EL1                MIDR
>>>> diff --git a/xen/include/asm-arm/cpufeature.h 
>>>> b/xen/include/asm-arm/cpufeature.h
>>>> index c7b5052992..6cf83d775b 100644
>>>> --- a/xen/include/asm-arm/cpufeature.h
>>>> +++ b/xen/include/asm-arm/cpufeature.h
>>>> @@ -148,6 +148,7 @@ struct cpuinfo_arm {
>>>>      union {
>>>>          uint64_t bits[2];
>>>>          struct {
>>>> +            /* PFR0 */
>>>>              unsigned long el0:4;
>>>>              unsigned long el1:4;
>>>>              unsigned long el2:4;
>>>> @@ -155,9 +156,23 @@ struct cpuinfo_arm {
>>>>              unsigned long fp:4;   /* Floating Point */
>>>>              unsigned long simd:4; /* Advanced SIMD */
>>>>              unsigned long gic:4;  /* GIC support */
>>>> -            unsigned long __res0:28;
>>>> +            unsigned long ras:4;
>>>> +            unsigned long sve:4;
>>>> +            unsigned long sel2:4;
>>>> +            unsigned long mpam:4;
>>>> +            unsigned long amu:4;
>>>> +            unsigned long dit:4;
>>>> +            unsigned long __res0:4;
>>>>              unsigned long csv2:4;
>>>> -            unsigned long __res1:4;
>>>> +            unsigned long cvs3:4;
>>>> +
>>>> +            /* PFR1 */
>>>> +            unsigned long bt:4;
>>>> +            unsigned long ssbs:4;
>>>> +            unsigned long mte:4;
>>>> +            unsigned long ras_frac:4;
>>>> +            unsigned long mpam_frac:4;
>>>> +            unsigned long __res1:44;
>>>>          };
>>>>      } pfr64;
>>>>  @@ -170,7 +185,7 @@ struct cpuinfo_arm {
>>>>      } aux64;
>>>>        union {
>>>> -        uint64_t bits[2];
>>>> +        uint64_t bits[3];
>>>>          struct {
>>>>              unsigned long pa_range:4;
>>>>              unsigned long asid_bits:4;
>>>> @@ -190,6 +205,8 @@ struct cpuinfo_arm {
>>>>              unsigned long pan:4;
>>>>              unsigned long __res1:8;
>>>>              unsigned long __res2:32;
>>>> +
>>>> +            unsigned long __res3:64;
>>>>          };
>>>>      } mm64;
>>>>  @@ -197,6 +214,10 @@ struct cpuinfo_arm {
>>>>          uint64_t bits[2];
>>>>      } isa64;
>>>>  +    struct {
>>>> +        uint64_t bits[1];
>>>> +    } zfr64;
>>>> +
>>>>  #endif
>>>>        /*
>>>> @@ -204,25 +225,38 @@ struct cpuinfo_arm {
>>>>       * when running in 32-bit mode.
>>>>       */
>>>>      union {
>>>> -        uint32_t bits[2];
>>>> +        uint32_t bits[3];
>>>>          struct {
>>>> +            /* PFR0 */
>>>>              unsigned long arm:4;
>>>>              unsigned long thumb:4;
>>>>              unsigned long jazelle:4;
>>>>              unsigned long thumbee:4;
>>>> -            unsigned long __res0:16;
>>>> +            unsigned long csv2:4;
>>>> +            unsigned long amu:4;
>>>> +            unsigned long dit:4;
>>>> +            unsigned long ras:4;
>>>>  +            /* PFR1 */
>>>>              unsigned long progmodel:4;
>>>>              unsigned long security:4;
>>>>              unsigned long mprofile:4;
>>>>              unsigned long virt:4;
>>>>              unsigned long gentimer:4;
>>>> -            unsigned long __res1:12;
>>>> +            unsigned long sec_frac:4;
>>>> +            unsigned long virt_frac:4;
>>>> +            unsigned long gic:4;
>>>> +
>>>> +            /* PFR2 */
>>>> +            unsigned long csv3:4;
>>>> +            unsigned long ssbs:4;
>>>> +            unsigned long ras_frac:4;
>>>> +            unsigned long __res2:20;
>>>>          };
>>>>      } pfr32;
>>>>        struct {
>>>> -        uint32_t bits[1];
>>>> +        uint32_t bits[2];
>>>>      } dbg32;
>>>>        struct {
>>>> @@ -230,12 +264,16 @@ struct cpuinfo_arm {
>>>>      } aux32;
>>>>        struct {
>>>> -        uint32_t bits[4];
>>>> +        uint32_t bits[6];
>>>>      } mm32;
>>>>        struct {
>>>> -        uint32_t bits[6];
>>>> +        uint32_t bits[7];
>>>>      } isa32;
>>>> +
>>>> +    struct {
>>>> +        uint64_t bits[3];
>>> 
>>> Shouldn't this be register_t?
>> I followed the scheme of the rest of the structure which
>> is always using uint64_t or uint32_t for bits definitions.
> 
> Right, but I am sure you will not be surprised if I tell you this is buggy 
> ;). The historical reason is, IIRC, the original spec of Armv8.0 described 
> them as 32-bit registers.
> 
> The spec was updated a while ago to clarify they are 64-bit when running in 
> AArch64. But a majority of them still have the top 32-bit RES0 (thankfully!).
> 
>> Why should I use register_t type for this one ?
> 
> Because the value is 32-bit on AArch32 and 64-bit for AArch64. I am ok to use 
> 64-bit still for AArch32, but it sounds a bit of a waste of memory.
> 
> What I care the most here is we use 64-bit for the new registers on AArch64. 
> Otherwise, we are going to soon discover that a bit above 32 was allocated 
> and not detected by Xen. I don't want to be the one doing the debugging!
> 
> Admittly, this is not a new issue. However, the more offending code we had 
> the more it will be difficul to get Xen to be fully compliant with the Armv8 
> spec.

I agree with that so I propose to do the following:
- create a new serie to fix those: 
        - use READ_SYSREG in cpufeature.c
        - use register_t in cpuinfo structure
- rebase my serie on top of this one and use the proper types on it

Might require more work but seem to be the right approach.

Cheers
Bertrand

> 
> Cheers,
> 
> -- 
> Julien Grall




 


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