Patchwork [06/27] arm64/sve: System register and exception syndrome definitions

login
register
mail settings
Submitter Dave Martin
Date Aug. 9, 2017, 12:05 p.m.
Message ID <1502280338-23002-7-git-send-email-Dave.Martin@arm.com>
Download mbox | patch
Permalink /patch/22013/
State New
Headers show

Comments

Dave Martin - Aug. 9, 2017, 12:05 p.m.
The SVE architecture adds some system registers, ID register fields
and a dedicated ESR exception class.

This patch adds the appropriate definitions that will be needed by
the kernel.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
---
 arch/arm64/include/asm/esr.h     |  3 ++-
 arch/arm64/include/asm/kvm_arm.h |  1 +
 arch/arm64/include/asm/sysreg.h  | 16 ++++++++++++++++
 arch/arm64/kernel/traps.c        |  1 +
 4 files changed, 20 insertions(+), 1 deletion(-)
Alex Bennée - Aug. 21, 2017, 9:33 a.m.
Dave Martin <Dave.Martin@arm.com> writes:

> The SVE architecture adds some system registers, ID register fields
> and a dedicated ESR exception class.
>
> This patch adds the appropriate definitions that will be needed by
> the kernel.
>
> Signed-off-by: Dave Martin <Dave.Martin@arm.com>
> ---
>  arch/arm64/include/asm/esr.h     |  3 ++-
>  arch/arm64/include/asm/kvm_arm.h |  1 +
>  arch/arm64/include/asm/sysreg.h  | 16 ++++++++++++++++
>  arch/arm64/kernel/traps.c        |  1 +
>  4 files changed, 20 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/include/asm/esr.h b/arch/arm64/include/asm/esr.h
> index 8cabd57..813629e 100644
> --- a/arch/arm64/include/asm/esr.h
> +++ b/arch/arm64/include/asm/esr.h
> @@ -43,7 +43,8 @@
>  #define ESR_ELx_EC_HVC64	(0x16)
>  #define ESR_ELx_EC_SMC64	(0x17)
>  #define ESR_ELx_EC_SYS64	(0x18)
> -/* Unallocated EC: 0x19 - 0x1E */
> +#define ESR_ELx_EC_SVE		(0x19)
> +/* Unallocated EC: 0x1A - 0x1E */
>  #define ESR_ELx_EC_IMP_DEF	(0x1f)
>  #define ESR_ELx_EC_IABT_LOW	(0x20)
>  #define ESR_ELx_EC_IABT_CUR	(0x21)
> diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
> index 61d694c..dbf0537 100644
> --- a/arch/arm64/include/asm/kvm_arm.h
> +++ b/arch/arm64/include/asm/kvm_arm.h
> @@ -185,6 +185,7 @@
>  #define CPTR_EL2_TCPAC	(1 << 31)
>  #define CPTR_EL2_TTA	(1 << 20)
>  #define CPTR_EL2_TFP	(1 << CPTR_EL2_TFP_SHIFT)
> +#define CPTR_EL2_TZ	(1 << 8)
>  #define CPTR_EL2_DEFAULT	0x000033ff
>
>  /* Hyp Debug Configuration Register bits */
> diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
> index 248339e..2d259e8 100644
> --- a/arch/arm64/include/asm/sysreg.h
> +++ b/arch/arm64/include/asm/sysreg.h
> @@ -145,6 +145,7 @@
>
>  #define SYS_ID_AA64PFR0_EL1		sys_reg(3, 0, 0, 4, 0)
>  #define SYS_ID_AA64PFR1_EL1		sys_reg(3, 0, 0, 4, 1)
> +#define SYS_ID_AA64ZFR0_EL1		sys_reg(3, 0, 0, 4, 4)
>
>  #define SYS_ID_AA64DFR0_EL1		sys_reg(3, 0, 0, 5, 0)
>  #define SYS_ID_AA64DFR1_EL1		sys_reg(3, 0, 0, 5, 1)
> @@ -160,6 +161,8 @@
>  #define SYS_ACTLR_EL1			sys_reg(3, 0, 1, 0, 1)
>  #define SYS_CPACR_EL1			sys_reg(3, 0, 1, 0, 2)
>
> +#define SYS_ZCR_EL1			sys_reg(3, 0, 1, 2, 0)
> +

I'll have to take these on trust. They are mentioned in both the ARM ARM
and the SVE supplement but I can't see any actual definitions of them.

>  #define SYS_TTBR0_EL1			sys_reg(3, 0, 2, 0, 0)
>  #define SYS_TTBR1_EL1			sys_reg(3, 0, 2, 0, 1)
>  #define SYS_TCR_EL1			sys_reg(3, 0, 2, 0, 2)
> @@ -250,6 +253,8 @@
>
>  #define SYS_PMCCFILTR_EL0		sys_reg (3, 3, 14, 15, 7)
>
> +#define SYS_ZCR_EL2			sys_reg(3, 4, 1, 2, 0)
> +
>  #define SYS_DACR32_EL2			sys_reg(3, 4, 3, 0, 0)
>  #define SYS_IFSR32_EL2			sys_reg(3, 4, 5, 0, 1)
>  #define SYS_FPEXC32_EL2			sys_reg(3, 4, 5, 3, 0)
> @@ -331,6 +336,7 @@
>  #define ID_AA64ISAR1_JSCVT_SHIFT	12
>
>  /* id_aa64pfr0 */
> +#define ID_AA64PFR0_SVE_SHIFT		32
>  #define ID_AA64PFR0_GIC_SHIFT		24
>  #define ID_AA64PFR0_ASIMD_SHIFT		20
>  #define ID_AA64PFR0_FP_SHIFT		16
> @@ -339,6 +345,7 @@
>  #define ID_AA64PFR0_EL1_SHIFT		4
>  #define ID_AA64PFR0_EL0_SHIFT		0
>
> +#define ID_AA64PFR0_SVE			0x1
>  #define ID_AA64PFR0_FP_NI		0xf
>  #define ID_AA64PFR0_FP_SUPPORTED	0x0
>  #define ID_AA64PFR0_ASIMD_NI		0xf
> @@ -440,6 +447,15 @@
>  #endif
>
>
> +#define ZCR_ELx_LEN_SHIFT	0
> +#define ZCR_ELx_LEN_SIZE	9
> +#define ZCR_ELx_LEN_MASK	0x1ff
> +
> +#define CPACR_EL1_ZEN_EL1EN	(1 << 16)
> +#define CPACR_EL1_ZEN_EL0EN	(1 << 17)
> +#define CPACR_EL1_ZEN		(CPACR_EL1_ZEN_EL1EN |
> CPACR_EL1_ZEN_EL0EN)

This is a little weird as it is a 2 bit field in which 00 and 11 are not
simply the sum of their bits. If the code wrote CPACR_EL1_ZEN_EL0EN |
CPACR_EL1_ZEN_EL1EN to the CPACR_EL1 you wouldn't get the expected behaviour.

> +
> +
>  /* Safe value for MPIDR_EL1: Bit31:RES1, Bit30:U:0, Bit24:MT:0 */
>  #define SYS_MPIDR_SAFE_VAL		(1UL << 31)
>
> diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
> index 0f047e9..8964795 100644
> --- a/arch/arm64/kernel/traps.c
> +++ b/arch/arm64/kernel/traps.c
> @@ -621,6 +621,7 @@ static const char *esr_class_str[] = {
>  	[ESR_ELx_EC_HVC64]		= "HVC (AArch64)",
>  	[ESR_ELx_EC_SMC64]		= "SMC (AArch64)",
>  	[ESR_ELx_EC_SYS64]		= "MSR/MRS (AArch64)",
> +	[ESR_ELx_EC_SVE]		= "SVE",
>  	[ESR_ELx_EC_IMP_DEF]		= "EL3 IMP DEF",
>  	[ESR_ELx_EC_IABT_LOW]		= "IABT (lower EL)",
>  	[ESR_ELx_EC_IABT_CUR]		= "IABT (current EL)",


--
Alex Bennée
Alex Bennée - Aug. 21, 2017, 12:34 p.m.
Alex Bennée <alex.bennee@linaro.org> writes:

> Dave Martin <Dave.Martin@arm.com> writes:
>
>> The SVE architecture adds some system registers, ID register fields
>> and a dedicated ESR exception class.
>>
>> This patch adds the appropriate definitions that will be needed by
>> the kernel.
>>
>> Signed-off-by: Dave Martin <Dave.Martin@arm.com>
>> ---
>>  arch/arm64/include/asm/esr.h     |  3 ++-
>>  arch/arm64/include/asm/kvm_arm.h |  1 +
>>  arch/arm64/include/asm/sysreg.h  | 16 ++++++++++++++++
>>  arch/arm64/kernel/traps.c        |  1 +
>>  4 files changed, 20 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arm64/include/asm/esr.h b/arch/arm64/include/asm/esr.h
>> index 8cabd57..813629e 100644
>> --- a/arch/arm64/include/asm/esr.h
>> +++ b/arch/arm64/include/asm/esr.h
>> @@ -43,7 +43,8 @@
>>  #define ESR_ELx_EC_HVC64	(0x16)
>>  #define ESR_ELx_EC_SMC64	(0x17)
>>  #define ESR_ELx_EC_SYS64	(0x18)
>> -/* Unallocated EC: 0x19 - 0x1E */
>> +#define ESR_ELx_EC_SVE		(0x19)
>> +/* Unallocated EC: 0x1A - 0x1E */
>>  #define ESR_ELx_EC_IMP_DEF	(0x1f)
>>  #define ESR_ELx_EC_IABT_LOW	(0x20)
>>  #define ESR_ELx_EC_IABT_CUR	(0x21)
>> diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
>> index 61d694c..dbf0537 100644
>> --- a/arch/arm64/include/asm/kvm_arm.h
>> +++ b/arch/arm64/include/asm/kvm_arm.h
>> @@ -185,6 +185,7 @@
>>  #define CPTR_EL2_TCPAC	(1 << 31)
>>  #define CPTR_EL2_TTA	(1 << 20)
>>  #define CPTR_EL2_TFP	(1 << CPTR_EL2_TFP_SHIFT)
>> +#define CPTR_EL2_TZ	(1 << 8)
>>  #define CPTR_EL2_DEFAULT	0x000033ff
>>
>>  /* Hyp Debug Configuration Register bits */
>> diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
>> index 248339e..2d259e8 100644
>> --- a/arch/arm64/include/asm/sysreg.h
>> +++ b/arch/arm64/include/asm/sysreg.h
>> @@ -145,6 +145,7 @@
>>
>>  #define SYS_ID_AA64PFR0_EL1		sys_reg(3, 0, 0, 4, 0)
>>  #define SYS_ID_AA64PFR1_EL1		sys_reg(3, 0, 0, 4, 1)
>> +#define SYS_ID_AA64ZFR0_EL1		sys_reg(3, 0, 0, 4, 4)
>>
>>  #define SYS_ID_AA64DFR0_EL1		sys_reg(3, 0, 0, 5, 0)
>>  #define SYS_ID_AA64DFR1_EL1		sys_reg(3, 0, 0, 5, 1)
>> @@ -160,6 +161,8 @@
>>  #define SYS_ACTLR_EL1			sys_reg(3, 0, 1, 0, 1)
>>  #define SYS_CPACR_EL1			sys_reg(3, 0, 1, 0, 2)
>>
>> +#define SYS_ZCR_EL1			sys_reg(3, 0, 1, 2, 0)
>> +
>
> I'll have to take these on trust. They are mentioned in both the ARM ARM
> and the SVE supplement but I can't see any actual definitions of them.
>
>>  #define SYS_TTBR0_EL1			sys_reg(3, 0, 2, 0, 0)
>>  #define SYS_TTBR1_EL1			sys_reg(3, 0, 2, 0, 1)
>>  #define SYS_TCR_EL1			sys_reg(3, 0, 2, 0, 2)
>> @@ -250,6 +253,8 @@
>>
>>  #define SYS_PMCCFILTR_EL0		sys_reg (3, 3, 14, 15, 7)
>>
>> +#define SYS_ZCR_EL2			sys_reg(3, 4, 1, 2, 0)
>> +

OK no I'm working directly from the unpacked ZIP file with the rest of
the details I think this should be:

  #define SYS_ZCR_EL2			sys_reg(3, 5, 1, 2, 0)

e.g. op1 = 101 / 5

>>  #define SYS_DACR32_EL2			sys_reg(3, 4, 3, 0, 0)
>>  #define SYS_IFSR32_EL2			sys_reg(3, 4, 5, 0, 1)
>>  #define SYS_FPEXC32_EL2			sys_reg(3, 4, 5, 3, 0)
>> @@ -331,6 +336,7 @@
>>  #define ID_AA64ISAR1_JSCVT_SHIFT	12
>>
>>  /* id_aa64pfr0 */
>> +#define ID_AA64PFR0_SVE_SHIFT		32
>>  #define ID_AA64PFR0_GIC_SHIFT		24
>>  #define ID_AA64PFR0_ASIMD_SHIFT		20
>>  #define ID_AA64PFR0_FP_SHIFT		16
>> @@ -339,6 +345,7 @@
>>  #define ID_AA64PFR0_EL1_SHIFT		4
>>  #define ID_AA64PFR0_EL0_SHIFT		0
>>
>> +#define ID_AA64PFR0_SVE			0x1
>>  #define ID_AA64PFR0_FP_NI		0xf
>>  #define ID_AA64PFR0_FP_SUPPORTED	0x0
>>  #define ID_AA64PFR0_ASIMD_NI		0xf
>> @@ -440,6 +447,15 @@
>>  #endif
>>
>>
>> +#define ZCR_ELx_LEN_SHIFT	0
>> +#define ZCR_ELx_LEN_SIZE	9
>> +#define ZCR_ELx_LEN_MASK	0x1ff
>> +

LEN should be 0/4/0xf

LEN, bits [3:0]

Constrains the scalable vector register length for EL1 and EL0 to (LEN+1)x128 bits.


>> +#define CPACR_EL1_ZEN_EL1EN	(1 << 16)
>> +#define CPACR_EL1_ZEN_EL0EN	(1 << 17)
>> +#define CPACR_EL1_ZEN		(CPACR_EL1_ZEN_EL1EN |
>> CPACR_EL1_ZEN_EL0EN)
>
> This is a little weird as it is a 2 bit field in which 00 and 11 are not
> simply the sum of their bits. If the code wrote CPACR_EL1_ZEN_EL0EN |
> CPACR_EL1_ZEN_EL1EN to the CPACR_EL1 you wouldn't get the expected behaviour.
>
>> +
>> +
>>  /* Safe value for MPIDR_EL1: Bit31:RES1, Bit30:U:0, Bit24:MT:0 */
>>  #define SYS_MPIDR_SAFE_VAL		(1UL << 31)
>>
>> diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
>> index 0f047e9..8964795 100644
>> --- a/arch/arm64/kernel/traps.c
>> +++ b/arch/arm64/kernel/traps.c
>> @@ -621,6 +621,7 @@ static const char *esr_class_str[] = {
>>  	[ESR_ELx_EC_HVC64]		= "HVC (AArch64)",
>>  	[ESR_ELx_EC_SMC64]		= "SMC (AArch64)",
>>  	[ESR_ELx_EC_SYS64]		= "MSR/MRS (AArch64)",
>> +	[ESR_ELx_EC_SVE]		= "SVE",
>>  	[ESR_ELx_EC_IMP_DEF]		= "EL3 IMP DEF",
>>  	[ESR_ELx_EC_IABT_LOW]		= "IABT (lower EL)",
>>  	[ESR_ELx_EC_IABT_CUR]		= "IABT (current EL)",


--
Alex Bennée
Dave Martin - Aug. 21, 2017, 1:56 p.m.
On Mon, Aug 21, 2017 at 10:33:55AM +0100, Alex Bennée wrote:
> 
> Dave Martin <Dave.Martin@arm.com> writes:
> 
> > The SVE architecture adds some system registers, ID register fields
> > and a dedicated ESR exception class.
> >
> > This patch adds the appropriate definitions that will be needed by
> > the kernel.
> >
> > Signed-off-by: Dave Martin <Dave.Martin@arm.com>
> > ---
> >  arch/arm64/include/asm/esr.h     |  3 ++-
> >  arch/arm64/include/asm/kvm_arm.h |  1 +
> >  arch/arm64/include/asm/sysreg.h  | 16 ++++++++++++++++
> >  arch/arm64/kernel/traps.c        |  1 +
> >  4 files changed, 20 insertions(+), 1 deletion(-)

[...]

> > diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
> > index 248339e..2d259e8 100644
> > --- a/arch/arm64/include/asm/sysreg.h
> > +++ b/arch/arm64/include/asm/sysreg.h

[...]

> > +#define SYS_ZCR_EL1			sys_reg(3, 0, 1, 2, 0)
> > +
> 
> I'll have to take these on trust. They are mentioned in both the ARM ARM
> and the SVE supplement but I can't see any actual definitions of them.

[I note from subsequent replies you've now found this in the
accompanying HTML]

[...]

> > +#define CPACR_EL1_ZEN_EL1EN	(1 << 16)
> > +#define CPACR_EL1_ZEN_EL0EN	(1 << 17)
> > +#define CPACR_EL1_ZEN		(CPACR_EL1_ZEN_EL1EN |
> > CPACR_EL1_ZEN_EL0EN)
> 
> This is a little weird as it is a 2 bit field in which 00 and 11 are not
> simply the sum of their bits. If the code wrote CPACR_EL1_ZEN_EL0EN |
> CPACR_EL1_ZEN_EL1EN to the CPACR_EL1 you wouldn't get the expected behaviour.

This seemed natural-ish if you believe that disabling at EL1 implies
disabling at EL0.  This is consistent with the way the traps at EL2/3
work, and lack of this property would be a sort of privilege inversion.

The meanings of the bits are not orthogonal, but it's still useful to be
able to twiddle EL0EN by itself when EL1EN is set (since we wan't to
control access for EL0 but leave EL1 access enabled).

Maybe comments would be sufficient:

#define CPACR_EL1_ZEN_EL1EN ... /* enable EL1 access */
#define CPACR_EL1_ZEN_EL0EN ... /* enable EL0 access, if EL1EN is also set */

I'm not sure how to make the names both reasonably terse and self-
escribing, but I'm open to ideas.

Cheers
---Dave
Dave Martin - Aug. 21, 2017, 2:26 p.m.
On Mon, Aug 21, 2017 at 01:34:38PM +0100, Alex Bennée wrote:
> 
> Alex Bennée <alex.bennee@linaro.org> writes:
> 
> > Dave Martin <Dave.Martin@arm.com> writes:

[...]

> OK no I'm working directly from the unpacked ZIP file with the rest of
> the details I think this should be:
> 
>   #define SYS_ZCR_EL2			sys_reg(3, 5, 1, 2, 0)
> 
> e.g. op1 = 101 / 5

No, that's the encoding for ZCR_EL12.  Where did you get this from?

(This encoding follows the general pattern of the v8.1 Virtualization
Host Extensions.)

[...]

> >> +#define ZCR_ELx_LEN_SHIFT	0
> >> +#define ZCR_ELx_LEN_SIZE	9
> >> +#define ZCR_ELx_LEN_MASK	0x1ff
> >> +
> 
> LEN should be 0/4/0xf
> 
> LEN, bits [3:0]
> 
> Constrains the scalable vector register length for EL1 and EL0 to
> (LEN+1)x128 bits.

The SVE supplement is not very explicit about the meaning of bits [8:4],
but they are reserved to extend the LEN field in the future, in case
that's ever needed for future architecture revisions.  I've aimed for
Linux to cope with this.

Basically bits [8:4] are read-as-zero, write-ignore today, but in
the future some or all of them may be LEN field bits.

In particular, this means that writing all bits [8:0] with 1 will
configure the largest supported vector length, even on future
architecture versions that may have a larger LEN field.

It didn't seem useful to distinguish the two classes of bits here.

Cheers
---Dave
Alex Bennée - Aug. 21, 2017, 2:36 p.m.
Dave Martin <Dave.Martin@arm.com> writes:

> On Mon, Aug 21, 2017 at 10:33:55AM +0100, Alex Bennée wrote:
>>
>> Dave Martin <Dave.Martin@arm.com> writes:
>>
>> > The SVE architecture adds some system registers, ID register fields
>> > and a dedicated ESR exception class.
>> >
>> > This patch adds the appropriate definitions that will be needed by
>> > the kernel.
>> >
>> > Signed-off-by: Dave Martin <Dave.Martin@arm.com>
>> > ---
>> >  arch/arm64/include/asm/esr.h     |  3 ++-
>> >  arch/arm64/include/asm/kvm_arm.h |  1 +
>> >  arch/arm64/include/asm/sysreg.h  | 16 ++++++++++++++++
>> >  arch/arm64/kernel/traps.c        |  1 +
>> >  4 files changed, 20 insertions(+), 1 deletion(-)
>
> [...]
>
>> > diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
>> > index 248339e..2d259e8 100644
>> > --- a/arch/arm64/include/asm/sysreg.h
>> > +++ b/arch/arm64/include/asm/sysreg.h
>
> [...]
>
>> > +#define SYS_ZCR_EL1			sys_reg(3, 0, 1, 2, 0)
>> > +
>>
>> I'll have to take these on trust. They are mentioned in both the ARM ARM
>> and the SVE supplement but I can't see any actual definitions of them.
>
> [I note from subsequent replies you've now found this in the
> accompanying HTML]
>
> [...]
>
>> > +#define CPACR_EL1_ZEN_EL1EN	(1 << 16)
>> > +#define CPACR_EL1_ZEN_EL0EN	(1 << 17)
>> > +#define CPACR_EL1_ZEN		(CPACR_EL1_ZEN_EL1EN |
>> > CPACR_EL1_ZEN_EL0EN)
>>
>> This is a little weird as it is a 2 bit field in which 00 and 11 are not
>> simply the sum of their bits. If the code wrote CPACR_EL1_ZEN_EL0EN |
>> CPACR_EL1_ZEN_EL1EN to the CPACR_EL1 you wouldn't get the expected behaviour.
>
> This seemed natural-ish if you believe that disabling at EL1 implies
> disabling at EL0.  This is consistent with the way the traps at EL2/3
> work, and lack of this property would be a sort of privilege inversion.
>
> The meanings of the bits are not orthogonal, but it's still useful to be
> able to twiddle EL0EN by itself when EL1EN is set (since we wan't to
> control access for EL0 but leave EL1 access enabled).
>
> Maybe comments would be sufficient:
>
> #define CPACR_EL1_ZEN_EL1EN ... /* enable EL1 access */
> #define CPACR_EL1_ZEN_EL0EN ... /* enable EL0 access, if EL1EN is also
> set */

Certainly it would help. I'll see as I go through the rest of the code
but it looks like a potential bear trap we should at least mitigate.

>
> I'm not sure how to make the names both reasonably terse and self-
> escribing, but I'm open to ideas.

Sorry no decent ideas. Naming things is hard as they say.

BTW see the follow-up mail for the other things I found....

--
Alex Bennée
Alex Bennée - Aug. 21, 2017, 2:50 p.m.
Dave Martin <Dave.Martin@arm.com> writes:

> On Mon, Aug 21, 2017 at 01:34:38PM +0100, Alex Bennée wrote:
>>
>> Alex Bennée <alex.bennee@linaro.org> writes:
>>
>> > Dave Martin <Dave.Martin@arm.com> writes:
>
> [...]
>
>> OK no I'm working directly from the unpacked ZIP file with the rest of
>> the details I think this should be:
>>
>>   #define SYS_ZCR_EL2			sys_reg(3, 5, 1, 2, 0)
>>
>> e.g. op1 = 101 / 5
>
> No, that's the encoding for ZCR_EL12.  Where did you get this from?

Sorry my mistake, -ETOOMANYBITTABLES....

>
> (This encoding follows the general pattern of the v8.1 Virtualization
> Host Extensions.)
>
> [...]
>
>> >> +#define ZCR_ELx_LEN_SHIFT	0
>> >> +#define ZCR_ELx_LEN_SIZE	9
>> >> +#define ZCR_ELx_LEN_MASK	0x1ff
>> >> +
>>
>> LEN should be 0/4/0xf
>>
>> LEN, bits [3:0]
>>
>> Constrains the scalable vector register length for EL1 and EL0 to
>> (LEN+1)x128 bits.
>
> The SVE supplement is not very explicit about the meaning of bits [8:4],
> but they are reserved to extend the LEN field in the future, in case
> that's ever needed for future architecture revisions.  I've aimed for
> Linux to cope with this.
>
> Basically bits [8:4] are read-as-zero, write-ignore today, but in
> the future some or all of them may be LEN field bits.
>
> In particular, this means that writing all bits [8:0] with 1 will
> configure the largest supported vector length, even on future
> architecture versions that may have a larger LEN field.

Ahh ok. It's not clear from the html and it is certainly implied in the
supplement (2.1.1) that the architectural max is:

  The size of every vector register is an IMPLEMENTATION DEFINED
  multiple of 128 bits, up to an architectural maximum of 2048 bits.

>
> It didn't seem useful to distinguish the two classes of bits here.

Maybe a comment clarifying would be useful then?

>
> Cheers
> ---Dave


--
Alex Bennée
Dave Martin - Aug. 21, 2017, 3:19 p.m.
On Mon, Aug 21, 2017 at 03:50:32PM +0100, Alex Bennée wrote:
> Dave Martin <Dave.Martin@arm.com> writes:
> > On Mon, Aug 21, 2017 at 01:34:38PM +0100, Alex Bennée wrote:

[...]

> >> > Dave Martin <Dave.Martin@arm.com> writes:

[...]

> >> >> +#define ZCR_ELx_LEN_SHIFT	0
> >> >> +#define ZCR_ELx_LEN_SIZE	9
> >> >> +#define ZCR_ELx_LEN_MASK	0x1ff
> >> >> +
> >>
> >> LEN should be 0/4/0xf
> >>
> >> LEN, bits [3:0]
> >>
> >> Constrains the scalable vector register length for EL1 and EL0 to
> >> (LEN+1)x128 bits.
> >
> > The SVE supplement is not very explicit about the meaning of bits [8:4],
> > but they are reserved to extend the LEN field in the future, in case
> > that's ever needed for future architecture revisions.  I've aimed for
> > Linux to cope with this.
> >
> > Basically bits [8:4] are read-as-zero, write-ignore today, but in
> > the future some or all of them may be LEN field bits.
> >
> > In particular, this means that writing all bits [8:0] with 1 will
> > configure the largest supported vector length, even on future
> > architecture versions that may have a larger LEN field.
> 
> Ahh ok. It's not clear from the html and it is certainly implied in the
> supplement (2.1.1) that the architectural max is:
> 
>   The size of every vector register is an IMPLEMENTATION DEFINED
>   multiple of 128 bits, up to an architectural maximum of 2048 bits.
> 
> >
> > It didn't seem useful to distinguish the two classes of bits here.
> 
> Maybe a comment clarifying would be useful then?

OK, I think I can say something like:

/*
 * The ZCR_ELx_LEN_* definitions intentionally include bits [8:4]
 * which are reserved by the SVE architecture for future expansion of
 * the LEN field, with compatible semantics.
 */

Any good?

Cheers
---Dave
Alex Bennée - Aug. 21, 2017, 3:34 p.m.
Dave Martin <Dave.Martin@arm.com> writes:

> On Mon, Aug 21, 2017 at 03:50:32PM +0100, Alex Bennée wrote:
>> Dave Martin <Dave.Martin@arm.com> writes:
>> > On Mon, Aug 21, 2017 at 01:34:38PM +0100, Alex Bennée wrote:
>
> [...]
>
>> >> > Dave Martin <Dave.Martin@arm.com> writes:
>
> [...]
>
>> >> >> +#define ZCR_ELx_LEN_SHIFT	0
>> >> >> +#define ZCR_ELx_LEN_SIZE	9
>> >> >> +#define ZCR_ELx_LEN_MASK	0x1ff
>> >> >> +
>> >>
>> >> LEN should be 0/4/0xf
>> >>
>> >> LEN, bits [3:0]
>> >>
>> >> Constrains the scalable vector register length for EL1 and EL0 to
>> >> (LEN+1)x128 bits.
>> >
>> > The SVE supplement is not very explicit about the meaning of bits [8:4],
>> > but they are reserved to extend the LEN field in the future, in case
>> > that's ever needed for future architecture revisions.  I've aimed for
>> > Linux to cope with this.
>> >
>> > Basically bits [8:4] are read-as-zero, write-ignore today, but in
>> > the future some or all of them may be LEN field bits.
>> >
>> > In particular, this means that writing all bits [8:0] with 1 will
>> > configure the largest supported vector length, even on future
>> > architecture versions that may have a larger LEN field.
>>
>> Ahh ok. It's not clear from the html and it is certainly implied in the
>> supplement (2.1.1) that the architectural max is:
>>
>>   The size of every vector register is an IMPLEMENTATION DEFINED
>>   multiple of 128 bits, up to an architectural maximum of 2048 bits.
>>
>> >
>> > It didn't seem useful to distinguish the two classes of bits here.
>>
>> Maybe a comment clarifying would be useful then?
>
> OK, I think I can say something like:
>
> /*
>  * The ZCR_ELx_LEN_* definitions intentionally include bits [8:4]
>  * which are reserved by the SVE architecture for future expansion of
>  * the LEN field, with compatible semantics.
>  */
>
> Any good?

Works for me ;-)

>
> Cheers
> ---Dave


--
Alex Bennée

Patch

diff --git a/arch/arm64/include/asm/esr.h b/arch/arm64/include/asm/esr.h
index 8cabd57..813629e 100644
--- a/arch/arm64/include/asm/esr.h
+++ b/arch/arm64/include/asm/esr.h
@@ -43,7 +43,8 @@ 
 #define ESR_ELx_EC_HVC64	(0x16)
 #define ESR_ELx_EC_SMC64	(0x17)
 #define ESR_ELx_EC_SYS64	(0x18)
-/* Unallocated EC: 0x19 - 0x1E */
+#define ESR_ELx_EC_SVE		(0x19)
+/* Unallocated EC: 0x1A - 0x1E */
 #define ESR_ELx_EC_IMP_DEF	(0x1f)
 #define ESR_ELx_EC_IABT_LOW	(0x20)
 #define ESR_ELx_EC_IABT_CUR	(0x21)
diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
index 61d694c..dbf0537 100644
--- a/arch/arm64/include/asm/kvm_arm.h
+++ b/arch/arm64/include/asm/kvm_arm.h
@@ -185,6 +185,7 @@ 
 #define CPTR_EL2_TCPAC	(1 << 31)
 #define CPTR_EL2_TTA	(1 << 20)
 #define CPTR_EL2_TFP	(1 << CPTR_EL2_TFP_SHIFT)
+#define CPTR_EL2_TZ	(1 << 8)
 #define CPTR_EL2_DEFAULT	0x000033ff
 
 /* Hyp Debug Configuration Register bits */
diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index 248339e..2d259e8 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -145,6 +145,7 @@ 
 
 #define SYS_ID_AA64PFR0_EL1		sys_reg(3, 0, 0, 4, 0)
 #define SYS_ID_AA64PFR1_EL1		sys_reg(3, 0, 0, 4, 1)
+#define SYS_ID_AA64ZFR0_EL1		sys_reg(3, 0, 0, 4, 4)
 
 #define SYS_ID_AA64DFR0_EL1		sys_reg(3, 0, 0, 5, 0)
 #define SYS_ID_AA64DFR1_EL1		sys_reg(3, 0, 0, 5, 1)
@@ -160,6 +161,8 @@ 
 #define SYS_ACTLR_EL1			sys_reg(3, 0, 1, 0, 1)
 #define SYS_CPACR_EL1			sys_reg(3, 0, 1, 0, 2)
 
+#define SYS_ZCR_EL1			sys_reg(3, 0, 1, 2, 0)
+
 #define SYS_TTBR0_EL1			sys_reg(3, 0, 2, 0, 0)
 #define SYS_TTBR1_EL1			sys_reg(3, 0, 2, 0, 1)
 #define SYS_TCR_EL1			sys_reg(3, 0, 2, 0, 2)
@@ -250,6 +253,8 @@ 
 
 #define SYS_PMCCFILTR_EL0		sys_reg (3, 3, 14, 15, 7)
 
+#define SYS_ZCR_EL2			sys_reg(3, 4, 1, 2, 0)
+
 #define SYS_DACR32_EL2			sys_reg(3, 4, 3, 0, 0)
 #define SYS_IFSR32_EL2			sys_reg(3, 4, 5, 0, 1)
 #define SYS_FPEXC32_EL2			sys_reg(3, 4, 5, 3, 0)
@@ -331,6 +336,7 @@ 
 #define ID_AA64ISAR1_JSCVT_SHIFT	12
 
 /* id_aa64pfr0 */
+#define ID_AA64PFR0_SVE_SHIFT		32
 #define ID_AA64PFR0_GIC_SHIFT		24
 #define ID_AA64PFR0_ASIMD_SHIFT		20
 #define ID_AA64PFR0_FP_SHIFT		16
@@ -339,6 +345,7 @@ 
 #define ID_AA64PFR0_EL1_SHIFT		4
 #define ID_AA64PFR0_EL0_SHIFT		0
 
+#define ID_AA64PFR0_SVE			0x1
 #define ID_AA64PFR0_FP_NI		0xf
 #define ID_AA64PFR0_FP_SUPPORTED	0x0
 #define ID_AA64PFR0_ASIMD_NI		0xf
@@ -440,6 +447,15 @@ 
 #endif
 
 
+#define ZCR_ELx_LEN_SHIFT	0
+#define ZCR_ELx_LEN_SIZE	9
+#define ZCR_ELx_LEN_MASK	0x1ff
+
+#define CPACR_EL1_ZEN_EL1EN	(1 << 16)
+#define CPACR_EL1_ZEN_EL0EN	(1 << 17)
+#define CPACR_EL1_ZEN		(CPACR_EL1_ZEN_EL1EN | CPACR_EL1_ZEN_EL0EN)
+
+
 /* Safe value for MPIDR_EL1: Bit31:RES1, Bit30:U:0, Bit24:MT:0 */
 #define SYS_MPIDR_SAFE_VAL		(1UL << 31)
 
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index 0f047e9..8964795 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -621,6 +621,7 @@  static const char *esr_class_str[] = {
 	[ESR_ELx_EC_HVC64]		= "HVC (AArch64)",
 	[ESR_ELx_EC_SMC64]		= "SMC (AArch64)",
 	[ESR_ELx_EC_SYS64]		= "MSR/MRS (AArch64)",
+	[ESR_ELx_EC_SVE]		= "SVE",
 	[ESR_ELx_EC_IMP_DEF]		= "EL3 IMP DEF",
 	[ESR_ELx_EC_IABT_LOW]		= "IABT (lower EL)",
 	[ESR_ELx_EC_IABT_CUR]		= "IABT (current EL)",