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From: Fuad Tabba <tabba@google.com>
To: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org
Cc: maz@kernel.org, oliver.upton@linux.dev, will@kernel.org,
	 joey.gouly@arm.com, suzuki.poulose@arm.com,
	yuzenghui@huawei.com,  catalin.marinas@arm.com,
	vladimir.murzin@arm.com, tabba@google.com
Subject: [PATCH v6 1/9] KVM: arm64: Fix Trace Buffer trapping for protected VMs
Date: Thu, 11 Dec 2025 10:47:01 +0000	[thread overview]
Message-ID: <20251211104710.151771-2-tabba@google.com> (raw)
In-Reply-To: <20251211104710.151771-1-tabba@google.com>

For protected VMs in pKVM, the hypervisor should trap accesses to trace
buffer system registers if Trace Buffer isn't supported by the VM.
However, the current code only traps if Trace Buffer External Mode isn't
supported.

Fix this by checking for FEAT_TRBE (Trace Buffer) rather than
FEAT_TRBE_EXT.

Fixes: 9d5261269098 ("KVM: arm64: Trap external trace for protected VMs")
Reported-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Fuad Tabba <tabba@google.com>
---
 arch/arm64/kvm/hyp/nvhe/pkvm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/hyp/nvhe/pkvm.c b/arch/arm64/kvm/hyp/nvhe/pkvm.c
index 43bde061b65d..8d06a246dfd1 100644
--- a/arch/arm64/kvm/hyp/nvhe/pkvm.c
+++ b/arch/arm64/kvm/hyp/nvhe/pkvm.c
@@ -117,7 +117,7 @@ static void pvm_init_traps_mdcr(struct kvm_vcpu *vcpu)
 	if (!kvm_has_feat(kvm, ID_AA64DFR0_EL1, TraceFilt, IMP))
 		val |= MDCR_EL2_TTRF;
 
-	if (!kvm_has_feat(kvm, ID_AA64DFR0_EL1, ExtTrcBuff, IMP))
+	if (!kvm_has_feat(kvm, ID_AA64DFR0_EL1, TraceBuffer, IMP))
 		val |= MDCR_EL2_E2TB_MASK;
 
 	/* Trap Debug Communications Channel registers */
-- 
2.52.0.223.gf5cc29aaa4-goog



  reply	other threads:[~2025-12-11 10:47 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-12-11 10:47 [PATCH v6 0/9] KVM: arm64: Fixes for guest CPU feature trapping and enabling Fuad Tabba
2025-12-11 10:47 ` Fuad Tabba [this message]
2025-12-11 10:47 ` [PATCH v6 2/9] KVM: arm64: Fix Trace Buffer trap polarity for protected VMs Fuad Tabba
2025-12-11 10:47 ` [PATCH v6 3/9] KVM: arm64: Fix MTE flag initialization " Fuad Tabba
2025-12-11 10:47 ` [PATCH v6 4/9] KVM: arm64: Introduce helper to calculate fault IPA offset Fuad Tabba
2025-12-11 10:47 ` [PATCH v6 5/9] KVM: arm64: Include VM type when checking VM capabilities in pKVM Fuad Tabba
2025-12-11 10:47 ` [PATCH v6 6/9] KVM: arm64: Do not allow KVM_CAP_ARM_MTE for any guest " Fuad Tabba
2025-12-11 10:47 ` [PATCH v6 7/9] KVM: arm64: Track KVM IOCTLs and their associated KVM caps Fuad Tabba
2025-12-11 10:47 ` [PATCH v6 8/9] KVM: arm64: Check whether a VM IOCTL is allowed in pKVM Fuad Tabba
2026-01-15 15:03   ` Marc Zyngier
2026-01-15 15:19     ` Fuad Tabba
2026-01-15 16:05       ` Marc Zyngier
2026-01-15 16:14         ` Fuad Tabba
2026-01-15 18:03           ` Marc Zyngier
2026-01-15 19:15             ` Fuad Tabba
2025-12-11 10:47 ` [PATCH v6 9/9] KVM: arm64: Prevent host from managing timer offsets for protected VMs Fuad Tabba
2026-01-15 21:55 ` [PATCH v6 0/9] KVM: arm64: Fixes for guest CPU feature trapping and enabling Marc Zyngier

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