Re: [PATCH v4 6/8] xen/arm: Add handler for cp15 ID registers

[Bertrand Marquis <Bertrand.Marquis@xxxxxxx>]

Hi Stefano,

> On 17 Dec 2020, at 23:37, Stefano Stabellini <sstabellini@xxxxxxxxxx> wrote:
> 
> On Thu, 17 Dec 2020, Bertrand Marquis wrote:
>> Add support for emulation of cp15 based ID registers (on arm32 or when
>> running a 32bit guest on arm64).
>> The handlers are returning the values stored in the guest_cpuinfo
>> structure for known registers and RAZ for all reserved registers.
>> In the current status the MVFR registers are no supported.
>> 
>> Signed-off-by: Bertrand Marquis <bertrand.marquis@xxxxxxx>
>> ---
>> Changes in V2: Rebase
>> Changes in V3:
>>  Add case definition for reserved registers
>>  Add handling of reserved registers as RAZ.
>>  Fix code style in GENERATE_TID3_INFO declaration
>> Changes in V4:
>>  Fix comment for missing t (no to not)
>>  Put cases for reserved registers directly in the code instead of using
>>  a define in the cpregs.h header.
>> 
>> ---
>> xen/arch/arm/vcpreg.c | 65 +++++++++++++++++++++++++++++++++++++++++++
>> 1 file changed, 65 insertions(+)
>> 
>> diff --git a/xen/arch/arm/vcpreg.c b/xen/arch/arm/vcpreg.c
>> index cdc91cdf5b..1fe07fe02a 100644
>> --- a/xen/arch/arm/vcpreg.c
>> +++ b/xen/arch/arm/vcpreg.c
>> @@ -155,6 +155,24 @@ TVM_REG32(CONTEXTIDR, CONTEXTIDR_EL1)
>>         break;                                                      \
>>     }
>> 
>> +/* Macro to generate easily case for ID co-processor emulation */
>> +#define GENERATE_TID3_INFO(reg, field, offset)                      \
>> +    case HSR_CPREG32(reg):                                          \
>> +    {                                                               \
>> +        return handle_ro_read_val(regs, regidx, cp32.read, hsr,     \
>> +                          1, guest_cpuinfo.field.bits[offset]);     \
> 
> This line is misaligned, but it can be adjusted on commit

Oh yes this was spotted by Julien on the previous serie and I forgot to fix it.

> 
> Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> 

Thanks
Bertrand

> 
> 
>> +    }
>> +
>> +/* helper to define cases for all registers for one CRm value */
>> +#define HSR_CPREG32_TID3_CASES(REG)     case HSR_CPREG32(p15,0,c0,REG,0): \
>> +                                        case HSR_CPREG32(p15,0,c0,REG,1): \
>> +                                        case HSR_CPREG32(p15,0,c0,REG,2): \
>> +                                        case HSR_CPREG32(p15,0,c0,REG,3): \
>> +                                        case HSR_CPREG32(p15,0,c0,REG,4): \
>> +                                        case HSR_CPREG32(p15,0,c0,REG,5): \
>> +                                        case HSR_CPREG32(p15,0,c0,REG,6): \
>> +                                        case HSR_CPREG32(p15,0,c0,REG,7)
>> +
>> void do_cp15_32(struct cpu_user_regs *regs, const union hsr hsr)
>> {
>>     const struct hsr_cp32 cp32 = hsr.cp32;
>> @@ -286,6 +304,53 @@ void do_cp15_32(struct cpu_user_regs *regs, const union 
>> hsr hsr)
>>          */
>>         return handle_raz_wi(regs, regidx, cp32.read, hsr, 1);
>> 
>> +    /*
>> +     * HCR_EL2.TID3
>> +     *
>> +     * This is trapping most Identification registers used by a guest
>> +     * to identify the processor features
>> +     */
>> +    GENERATE_TID3_INFO(ID_PFR0, pfr32, 0)
>> +    GENERATE_TID3_INFO(ID_PFR1, pfr32, 1)
>> +    GENERATE_TID3_INFO(ID_PFR2, pfr32, 2)
>> +    GENERATE_TID3_INFO(ID_DFR0, dbg32, 0)
>> +    GENERATE_TID3_INFO(ID_DFR1, dbg32, 1)
>> +    GENERATE_TID3_INFO(ID_AFR0, aux32, 0)
>> +    GENERATE_TID3_INFO(ID_MMFR0, mm32, 0)
>> +    GENERATE_TID3_INFO(ID_MMFR1, mm32, 1)
>> +    GENERATE_TID3_INFO(ID_MMFR2, mm32, 2)
>> +    GENERATE_TID3_INFO(ID_MMFR3, mm32, 3)
>> +    GENERATE_TID3_INFO(ID_MMFR4, mm32, 4)
>> +    GENERATE_TID3_INFO(ID_MMFR5, mm32, 5)
>> +    GENERATE_TID3_INFO(ID_ISAR0, isa32, 0)
>> +    GENERATE_TID3_INFO(ID_ISAR1, isa32, 1)
>> +    GENERATE_TID3_INFO(ID_ISAR2, isa32, 2)
>> +    GENERATE_TID3_INFO(ID_ISAR3, isa32, 3)
>> +    GENERATE_TID3_INFO(ID_ISAR4, isa32, 4)
>> +    GENERATE_TID3_INFO(ID_ISAR5, isa32, 5)
>> +    GENERATE_TID3_INFO(ID_ISAR6, isa32, 6)
>> +    /* MVFR registers are in cp10 not cp15 */
>> +
>> +    /*
>> +     * Those cases are catching all Reserved registers trapped by TID3 which
>> +     * currently have no assignment.
>> +     * HCR.TID3 is trapping all registers in the group 3:
>> +     * coproc == p15, opc1 == 0, CRn == c0, CRm == {c2-c7}, opc2 == {0-7}.
>> +     * Those registers are defined as being RO in the Arm Architecture
>> +     * Reference manual Armv8 (Chapter D12.3.2 of issue F.c) so handle them
>> +     * as Read-only read as zero.
>> +     */
>> +    case HSR_CPREG32(p15,0,c0,c3,0):
>> +    case HSR_CPREG32(p15,0,c0,c3,1):
>> +    case HSR_CPREG32(p15,0,c0,c3,2):
>> +    case HSR_CPREG32(p15,0,c0,c3,3):
>> +    case HSR_CPREG32(p15,0,c0,c3,7):
>> +    HSR_CPREG32_TID3_CASES(c4):
>> +    HSR_CPREG32_TID3_CASES(c5):
>> +    HSR_CPREG32_TID3_CASES(c6):
>> +    HSR_CPREG32_TID3_CASES(c7):
>> +        return handle_ro_raz(regs, regidx, cp32.read, hsr, 1);
>> +
>>     /*
>>      * HCR_EL2.TIDCP
>>      *
>> -- 
>> 2.17.1