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arm64: Expose SVE2 features for userspace

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This patch provides support for reporting the presence of SVE2 and
its optional features to userspace.

This will also enable visibility of SVE2 for guests, when KVM
support for SVE-enabled guests is available.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Dave Martin 2019-04-18 18:41:38 +01:00 committed by Will Deacon
parent dd523791c9
commit 06a916feca
9 changed files with 108 additions and 1 deletions
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16
Documentation/arm64/cpu-feature-registers.txt
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@ -209,6 +209,22 @@ infrastructure:
| AT | [35-32] | y |
x--------------------------------------------------x
6) ID_AA64ZFR0_EL1 - SVE feature ID register 0
x--------------------------------------------------x
| Name | bits | visible |
|--------------------------------------------------|
| SM4 | [43-40] | y |
|--------------------------------------------------|
| SHA3 | [35-32] | y |
|--------------------------------------------------|
| BitPerm | [19-16] | y |
|--------------------------------------------------|
| AES | [7-4] | y |
|--------------------------------------------------|
| SVEVer | [3-0] | y |
x--------------------------------------------------x
Appendix I: Example
---------------------------

24
Documentation/arm64/elf_hwcaps.txt
View File

@ -163,6 +163,30 @@ HWCAP_SVE
Functionality implied by ID_AA64PFR0_EL1.SVE == 0b0001.
HWCAP2_SVE2
Functionality implied by ID_AA64ZFR0_EL1.SVEVer == 0b0001.
HWCAP2_SVEAES
Functionality implied by ID_AA64ZFR0_EL1.AES == 0b0001.
HWCAP2_SVEPMULL
Functionality implied by ID_AA64ZFR0_EL1.AES == 0b0010.
HWCAP2_SVEBITPERM
Functionality implied by ID_AA64ZFR0_EL1.BitPerm == 0b0001.
HWCAP2_SVESHA3
Functionality implied by ID_AA64ZFR0_EL1.SHA3 == 0b0001.
HWCAP2_SVESM4
Functionality implied by ID_AA64ZFR0_EL1.SM4 == 0b0001.
HWCAP_ASIMDFHM
Functionality implied by ID_AA64ISAR0_EL1.FHM == 0b0001.

17
Documentation/arm64/sve.txt
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@ -34,6 +34,23 @@ model features for SVE is included in Appendix A.
following sections: software that needs to verify that those interfaces are
present must check for HWCAP_SVE instead.
* On hardware that supports the SVE2 extensions, HWCAP2_SVE2 will also
be reported in the AT_HWCAP2 aux vector entry. In addition to this,
optional extensions to SVE2 may be reported by the presence of:
HWCAP2_SVE2
HWCAP2_SVEAES
HWCAP2_SVEPMULL
HWCAP2_SVEBITPERM
HWCAP2_SVESHA3
HWCAP2_SVESM4
This list may be extended over time as the SVE architecture evolves.
These extensions are also reported via the CPU ID register ID_AA64ZFR0_EL1,
which userspace can read using an MRS instruction. See elf_hwcaps.txt and
cpu-feature-registers.txt for details.
* Debuggers should restrict themselves to interacting with the target via the
NT_ARM_SVE regset. The recommended way of detecting support for this regset
is to connect to a target process first and then attempt a

3
arch/arm64/Kconfig
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@ -1372,6 +1372,9 @@ config ARM64_SVE
To enable use of this extension on CPUs that implement it, say Y.
On CPUs that support the SVE2 extensions, this option will enable
those too.
Note that for architectural reasons, firmware _must_ implement SVE
support when running on SVE capable hardware. The required support
is present in:

6
arch/arm64/include/asm/hwcap.h
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@ -89,6 +89,12 @@
#define __khwcap2_feature(x) (const_ilog2(HWCAP2_ ## x) + 32)
#define KERNEL_HWCAP_DCPODP __khwcap2_feature(DCPODP)
#define KERNEL_HWCAP_SVE2 __khwcap2_feature(SVE2)
#define KERNEL_HWCAP_SVEAES __khwcap2_feature(SVEAES)
#define KERNEL_HWCAP_SVEPMULL __khwcap2_feature(SVEPMULL)
#define KERNEL_HWCAP_SVEBITPERM __khwcap2_feature(SVEBITPERM)
#define KERNEL_HWCAP_SVESHA3 __khwcap2_feature(SVESHA3)
#define KERNEL_HWCAP_SVESM4 __khwcap2_feature(SVESM4)
/*
* This yields a mask that user programs can use to figure out what

14
arch/arm64/include/asm/sysreg.h
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@ -606,6 +606,20 @@
#define ID_AA64PFR1_SSBS_PSTATE_ONLY 1
#define ID_AA64PFR1_SSBS_PSTATE_INSNS 2
/* id_aa64zfr0 */
#define ID_AA64ZFR0_SM4_SHIFT 40
#define ID_AA64ZFR0_SHA3_SHIFT 32
#define ID_AA64ZFR0_BITPERM_SHIFT 16
#define ID_AA64ZFR0_AES_SHIFT 4
#define ID_AA64ZFR0_SVEVER_SHIFT 0
#define ID_AA64ZFR0_SM4 0x1
#define ID_AA64ZFR0_SHA3 0x1
#define ID_AA64ZFR0_BITPERM 0x1
#define ID_AA64ZFR0_AES 0x1
#define ID_AA64ZFR0_AES_PMULL 0x2
#define ID_AA64ZFR0_SVEVER_SVE2 0x1
/* id_aa64mmfr0 */
#define ID_AA64MMFR0_TGRAN4_SHIFT 28
#define ID_AA64MMFR0_TGRAN64_SHIFT 24

6
arch/arm64/include/uapi/asm/hwcap.h
View File

@ -57,5 +57,11 @@
* HWCAP2 flags - for AT_HWCAP2
*/
#define HWCAP2_DCPODP (1 << 0)
#define HWCAP2_SVE2 (1 << 1)
#define HWCAP2_SVEAES (1 << 2)
#define HWCAP2_SVEPMULL (1 << 3)
#define HWCAP2_SVEBITPERM (1 << 4)
#define HWCAP2_SVESHA3 (1 << 5)
#define HWCAP2_SVESM4 (1 << 6)
#endif /* _UAPI__ASM_HWCAP_H */

17
arch/arm64/kernel/cpufeature.c
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@ -184,6 +184,15 @@ static const struct arm64_ftr_bits ftr_id_aa64pfr1[] = {
ARM64_FTR_END,
};
static const struct arm64_ftr_bits ftr_id_aa64zfr0[] = {
ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ZFR0_SM4_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ZFR0_SHA3_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ZFR0_BITPERM_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ZFR0_AES_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ZFR0_SVEVER_SHIFT, 4, 0),
ARM64_FTR_END,
};
static const struct arm64_ftr_bits ftr_id_aa64mmfr0[] = {
S_ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR0_TGRAN4_SHIFT, 4, ID_AA64MMFR0_TGRAN4_NI),
S_ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR0_TGRAN64_SHIFT, 4, ID_AA64MMFR0_TGRAN64_NI),
@ -392,7 +401,7 @@ static const struct __ftr_reg_entry {
/* Op1 = 0, CRn = 0, CRm = 4 */
ARM64_FTR_REG(SYS_ID_AA64PFR0_EL1, ftr_id_aa64pfr0),
ARM64_FTR_REG(SYS_ID_AA64PFR1_EL1, ftr_id_aa64pfr1),
ARM64_FTR_REG(SYS_ID_AA64ZFR0_EL1, ftr_raz),
ARM64_FTR_REG(SYS_ID_AA64ZFR0_EL1, ftr_id_aa64zfr0),
/* Op1 = 0, CRn = 0, CRm = 5 */
ARM64_FTR_REG(SYS_ID_AA64DFR0_EL1, ftr_id_aa64dfr0),
@ -1610,6 +1619,12 @@ static const struct arm64_cpu_capabilities arm64_elf_hwcaps[] = {
HWCAP_CAP(SYS_ID_AA64MMFR2_EL1, ID_AA64MMFR2_AT_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_USCAT),
#ifdef CONFIG_ARM64_SVE
HWCAP_CAP(SYS_ID_AA64PFR0_EL1, ID_AA64PFR0_SVE_SHIFT, FTR_UNSIGNED, ID_AA64PFR0_SVE, CAP_HWCAP, KERNEL_HWCAP_SVE),
HWCAP_CAP(SYS_ID_AA64ZFR0_EL1, ID_AA64ZFR0_SVEVER_SHIFT, FTR_UNSIGNED, ID_AA64ZFR0_SVEVER_SVE2, CAP_HWCAP, KERNEL_HWCAP_SVE2),
HWCAP_CAP(SYS_ID_AA64ZFR0_EL1, ID_AA64ZFR0_AES_SHIFT, FTR_UNSIGNED, ID_AA64ZFR0_AES, CAP_HWCAP, KERNEL_HWCAP_SVEAES),
HWCAP_CAP(SYS_ID_AA64ZFR0_EL1, ID_AA64ZFR0_AES_SHIFT, FTR_UNSIGNED, ID_AA64ZFR0_AES_PMULL, CAP_HWCAP, KERNEL_HWCAP_SVEPMULL),
HWCAP_CAP(SYS_ID_AA64ZFR0_EL1, ID_AA64ZFR0_BITPERM_SHIFT, FTR_UNSIGNED, ID_AA64ZFR0_BITPERM, CAP_HWCAP, KERNEL_HWCAP_SVEBITPERM),
HWCAP_CAP(SYS_ID_AA64ZFR0_EL1, ID_AA64ZFR0_SHA3_SHIFT, FTR_UNSIGNED, ID_AA64ZFR0_SHA3, CAP_HWCAP, KERNEL_HWCAP_SVESHA3),
HWCAP_CAP(SYS_ID_AA64ZFR0_EL1, ID_AA64ZFR0_SM4_SHIFT, FTR_UNSIGNED, ID_AA64ZFR0_SM4, CAP_HWCAP, KERNEL_HWCAP_SVESM4),
#endif
HWCAP_CAP(SYS_ID_AA64PFR1_EL1, ID_AA64PFR1_SSBS_SHIFT, FTR_UNSIGNED, ID_AA64PFR1_SSBS_PSTATE_INSNS, CAP_HWCAP, KERNEL_HWCAP_SSBS),
#ifdef CONFIG_ARM64_PTR_AUTH

6
arch/arm64/kernel/cpuinfo.c
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@ -86,6 +86,12 @@ static const char *const hwcap_str[] = {
"paca",
"pacg",
"dcpodp",
"sve2",
"sveaes",
"svepmull",
"svebitperm",
"svesha3",
"svesm4",
NULL
};