linux-kernel - [RFC kvmtool 24/31] arm64: Don't try to debug a realm

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Message-Id: <20230127113932.166089-25-suzuki.poulose@arm.com>
Date:   Fri, 27 Jan 2023 11:39:25 +0000
From:   Suzuki K Poulose <suzuki.poulose@....com>
To:     kvm@...r.kernel.org, kvmarm@...ts.linux.dev
Cc:     suzuki.poulose@....com,
        Alexandru Elisei <alexandru.elisei@....com>,
        Andrew Jones <andrew.jones@...ux.dev>,
        Christoffer Dall <christoffer.dall@....com>,
        Fuad Tabba <tabba@...gle.com>,
        Jean-Philippe Brucker <jean-philippe@...aro.org>,
        Joey Gouly <Joey.Gouly@....com>, Marc Zyngier <maz@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Oliver Upton <oliver.upton@...ux.dev>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Quentin Perret <qperret@...gle.com>,
        Steven Price <steven.price@....com>,
        Thomas Huth <thuth@...hat.com>, Will Deacon <will@...nel.org>,
        Zenghui Yu <yuzenghui@...wei.com>, linux-coco@...ts.linux.dev,
        kvmarm@...ts.cs.columbia.edu, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: [RFC kvmtool 24/31] arm64: Don't try to debug a realm

From: Alexandru Elisei <alexandru.elisei@....com>

Don't read the register values for a running realm, because they don't
reflect the actual hardware state of a realm. And don't try to read realm
memory, because that will promptly lead to kvmtool being killed.

Signed-off-by: Alexandru Elisei <alexandru.elisei@....com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
---
 arm/aarch64/kvm-cpu.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arm/aarch64/kvm-cpu.c b/arm/aarch64/kvm-cpu.c
index 32fa7609..a29a3413 100644
--- a/arm/aarch64/kvm-cpu.c
+++ b/arm/aarch64/kvm-cpu.c
@@ -250,6 +250,9 @@ void kvm_cpu__show_code(struct kvm_cpu *vcpu)
 
 	reg.addr = (u64)&data;
 
+	if (vcpu->kvm->cfg.arch.is_realm)
+		return;
+
 	dprintf(debug_fd, "\n*pc:\n");
 	reg.id = ARM64_CORE_REG(regs.pc);
 	if (ioctl(vcpu->vcpu_fd, KVM_GET_ONE_REG, &reg) < 0)
@@ -274,6 +277,11 @@ void kvm_cpu__show_registers(struct kvm_cpu *vcpu)
 	reg.addr = (u64)&data;
 	dprintf(debug_fd, "\n Registers:\n");
 
+	if (vcpu->kvm->cfg.arch.is_realm) {
+		dprintf(debug_fd, " UNACCESSIBLE\n");
+		return;
+	}
+
 	reg.id		= ARM64_CORE_REG(regs.pc);
 	if (ioctl(vcpu->vcpu_fd, KVM_GET_ONE_REG, &reg) < 0)
 		die("KVM_GET_ONE_REG failed (pc)");
-- 
2.34.1