]> git.proxmox.com Git - mirror_ubuntu-kernels.git/commit
arm64/sve: Report SVE to userspace via CPUID only if supported
authorDave Martin <Dave.Martin@arm.com>
Thu, 14 Dec 2017 14:03:44 +0000 (14:03 +0000)
committerWill Deacon <will.deacon@arm.com>
Thu, 14 Dec 2017 15:14:30 +0000 (15:14 +0000)
commit3fab39997a98b97138c886978af660c4f6c7e9e6
treeeaf191d0def5b13d26c93f53365a52795e693f69
parent1d08a044cf12aee37dfd54837558e3295287b343
arm64/sve: Report SVE to userspace via CPUID only if supported

Currently, the SVE field in ID_AA64PFR0_EL1 is visible
unconditionally to userspace via the CPU ID register emulation,
irrespective of the kernel config.  This means that if a kernel
configured with CONFIG_ARM64_SVE=n is run on SVE-capable hardware,
userspace will see SVE reported as present in the ID regs even
though the kernel forbids execution of SVE instructions.

This patch makes the exposure of the SVE field in ID_AA64PFR0_EL1
conditional on CONFIG_ARM64_SVE=y.

Since future architecture features are likely to encounter a
similar requirement, this patch adds a suitable helper macros for
use when declaring config-conditional ID register fields.

Fixes: 43994d824e84 ("arm64/sve: Detect SVE and activate runtime support")
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Reported-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Cc: Suzuki Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
arch/arm64/include/asm/cpufeature.h
arch/arm64/kernel/cpufeature.c