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From: Mark Brown <broonie@kernel.org>
To: Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>, Marc Zyngier <maz@kernel.org>
Cc: Peter Maydell <peter.maydell@linaro.org>,
	Richard Henderson <richard.henderson@linaro.org>,
	Vincent Donnefort <vdonnefort@google.com>,
	James Morse <james.morse@arm.com>,
	Alexandru Elisei <alexandru.elisei@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Oliver Upton <oliver.upton@linux.dev>,
	linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
	Mark Brown <broonie@kernel.org>
Subject: [PATCH v1 1/2] arm64/cpufeature: Add feature detection for fine grained traps
Date: Thu, 27 Oct 2022 21:52:45 +0100	[thread overview]
Message-ID: <20221027205246.812586-2-broonie@kernel.org> (raw)
In-Reply-To: <20221027205246.812586-1-broonie@kernel.org>

Virtualisation support for SME depends on FEAT_FGT since it uses fine
grained traps to control access to SMPRI_EL1 and (for nVHE) TPIDR2_EL0
but systems have been encountered which implement SME without VHE. In
order to work around such systems we need to detect the absence of
FEAT_FGT, add detection in the cpufeature code.

Signed-off-by: Mark Brown <broonie@kernel.org>
---
 arch/arm64/kernel/cpufeature.c | 11 +++++++++++
 arch/arm64/tools/cpucaps       |  1 +
 2 files changed, 12 insertions(+)

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 6062454a9067..8ded72a8ccee 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -2590,6 +2590,17 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
 		.matches = has_cpuid_feature,
 		.min_field_value = 1,
 	},
+	{
+		.desc = "Fine Grained Traps",
+		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
+		.capability = ARM64_HAS_FGT,
+		.sys_reg = SYS_ID_AA64MMFR0_EL1,
+		.sign = FTR_UNSIGNED,
+		.field_pos = ID_AA64MMFR0_EL1_FGT_SHIFT,
+		.field_width = ID_AA64MMFR0_EL1_FGT_WIDTH,
+		.min_field_value = ID_AA64MMFR0_EL1_FGT_IMP,
+		.matches = has_cpuid_feature,
+	},
 #ifdef CONFIG_ARM64_SME
 	{
 		.desc = "Scalable Matrix Extension",
diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps
index f1c0347ec31a..2553c7559412 100644
--- a/arch/arm64/tools/cpucaps
+++ b/arch/arm64/tools/cpucaps
@@ -23,6 +23,7 @@ HAS_DCPOP
 HAS_E0PD
 HAS_ECV
 HAS_EPAN
+HAS_FGT
 HAS_GENERIC_AUTH
 HAS_GENERIC_AUTH_ARCH_QARMA3
 HAS_GENERIC_AUTH_ARCH_QARMA5
-- 
2.30.2


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  reply	other threads:[~2022-10-27 20:56 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-10-27 20:52 [PATCH v1 0/2] KVM: arm: Refuse to enable KVM on systems with SME but not FGT Mark Brown
2022-10-27 20:52 ` Mark Brown [this message]
2022-10-27 20:52 ` [PATCH v1 2/2] KVM: arm: Refuse to enable KVM on systems with FEAT_SME but not FEAT_FGT Mark Brown
2022-10-27 21:17 ` [PATCH v1 0/2] KVM: arm: Refuse to enable KVM on systems with SME but not FGT Richard Henderson
2022-10-29 11:46 ` Marc Zyngier
2022-10-30 17:44   ` Catalin Marinas
2022-10-31 12:38   ` Mark Brown

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