linux-kernel - [PATCH v9 4/6] arm64: kvm: Expose KVM_ARM_CAP

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Message-Id: <20210301142315.30920-5-steven.price@arm.com>
Date:   Mon,  1 Mar 2021 14:23:13 +0000
From:   Steven Price <steven.price@....com>
To:     Catalin Marinas <catalin.marinas@....com>,
        Marc Zyngier <maz@...nel.org>, Will Deacon <will@...nel.org>
Cc:     Steven Price <steven.price@....com>,
        James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        kvmarm@...ts.cs.columbia.edu, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, Dave Martin <Dave.Martin@....com>,
        Mark Rutland <mark.rutland@....com>,
        Thomas Gleixner <tglx@...utronix.de>, qemu-devel@...gnu.org,
        Juan Quintela <quintela@...hat.com>,
        "Dr. David Alan Gilbert" <dgilbert@...hat.com>,
        Richard Henderson <richard.henderson@...aro.org>,
        Peter Maydell <peter.maydell@...aro.org>,
        Haibo Xu <Haibo.Xu@....com>, Andrew Jones <drjones@...hat.com>
Subject: [PATCH v9 4/6] arm64: kvm: Expose KVM_ARM_CAP_MTE

It's now safe for the VMM to enable MTE in a guest, so expose the
capability to user space.

Signed-off-by: Steven Price <steven.price@....com>
---
 arch/arm64/kvm/arm.c      | 9 +++++++++
 arch/arm64/kvm/sys_regs.c | 3 +++
 2 files changed, 12 insertions(+)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index fc4c95dd2d26..46bf319f6cb7 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -93,6 +93,12 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
 		r = 0;
 		kvm->arch.return_nisv_io_abort_to_user = true;
 		break;
+	case KVM_CAP_ARM_MTE:
+		if (!system_supports_mte() || kvm->created_vcpus)
+			return -EINVAL;
+		r = 0;
+		kvm->arch.mte_enabled = true;
+		break;
 	default:
 		r = -EINVAL;
 		break;
@@ -234,6 +240,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 		 */
 		r = 1;
 		break;
+	case KVM_CAP_ARM_MTE:
+		r = system_supports_mte();
+		break;
 	case KVM_CAP_STEAL_TIME:
 		r = kvm_arm_pvtime_supported();
 		break;
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 17cb6256f205..5793499334e3 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1304,6 +1304,9 @@ static bool access_ccsidr(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
 static unsigned int mte_visibility(const struct kvm_vcpu *vcpu,
 				   const struct sys_reg_desc *rd)
 {
+	if (kvm_has_mte(vcpu->kvm))
+		return 0;
+
 	return REG_HIDDEN;
 }
 
-- 
2.20.1