linux-kernel - [PATCH v2 3/7] arm64: cpufeature: Fix the type of no FP/SIMD capability

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Message-Id: <20191217183402.2259904-4-suzuki.poulose@arm.com>
Date:   Tue, 17 Dec 2019 18:33:58 +0000
From:   Suzuki K Poulose <suzuki.poulose@....com>
To:     linux-arm-kernel@...ts.infradead.org
Cc:     linux-kernel@...r.kernel.org, will@...nel.org, maz@...nel.org,
        mark.rutland@....com, dave.martin@....com, catalin.marinas@....com,
        ard.biesheuvel@...aro.org, christoffer.dall@....com,
        Suzuki K Poulose <suzuki.poulose@....com>
Subject: [PATCH v2 3/7] arm64: cpufeature: Fix the type of no FP/SIMD capability

The NO_FPSIMD capability is defined with scope SYSTEM, which implies
that the "absence" of FP/SIMD on at least one CPU is detected only
after all the SMP CPUs are brought up. However, we use the status
of this capability for every context switch. So, let us change
the scope to LOCAL_CPU to allow the detection of this capability
as and when the first CPU without FP is brought up.

Also, the current type allows hotplugged CPU to be brought up without
FP/SIMD when all the current CPUs have FP/SIMD and we have the userspace
up. Fix both of these issues by changing the capability to
BOOT_RESTRICTED_LOCAL_CPU_FEATURE.

Fixes: 82e0191a1aa11abf ("arm64: Support systems without FP/ASIMD")
Cc: Will Deacon <will@...nel.org>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Catalin Marinas <catalin.marinas@....com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
---
 arch/arm64/kernel/cpufeature.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index d25ad65bfac2..2fc9f18e2d2d 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1369,7 +1369,7 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
 	{
 		/* FP/SIMD is not implemented */
 		.capability = ARM64_HAS_NO_FPSIMD,
-		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
+		.type = ARM64_CPUCAP_BOOT_RESTRICTED_CPU_LOCAL_FEATURE,
 		.min_field_value = 0,
 		.matches = has_no_fpsimd,
 	},
-- 
2.23.0