linux-kernel - [PATCH 2/2] KVM: arm64: Correct test for ICH_HCR_EL2

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Message-ID: <20251208152724.3637157-4-sascha.bischoff@arm.com>
Date: Mon, 8 Dec 2025 15:28:23 +0000
From: Sascha Bischoff <Sascha.Bischoff@....com>
To: "sascha.bischoff@...glemail.com" <sascha.bischoff@...glemail.com>,
	"linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "kvmarm@...ts.linux.dev"
	<kvmarm@...ts.linux.dev>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "kvm@...r.kernel.org" <kvm@...r.kernel.org>
CC: nd <nd@....com>, "maz@...nel.org" <maz@...nel.org>,
	"oliver.upton@...ux.dev" <oliver.upton@...ux.dev>, Joey Gouly
	<Joey.Gouly@....com>, Suzuki Poulose <Suzuki.Poulose@....com>,
	"yuzenghui@...wei.com" <yuzenghui@...wei.com>, "will@...nel.org"
	<will@...nel.org>
Subject: [PATCH 2/2] KVM: arm64: Correct test for ICH_HCR_EL2_TDIR cap for
 GICv5 hosts

The original order of checks in the ICH_HCR_EL2_TDIR test returned
with false early in the case where the native GICv3 CPUIF was not
present. The result was that on GICv5 hosts with legacy support -
which do not have the GICv3 CPUIF - the test always returned false.

Reshuffle the checks such that support for GICv5 legacy is checked
prior to checking for the native GICv3 CPUIF.

Signed-off-by: Sascha Bischoff <sascha.bischoff@....com>
Fixes: 2a28810cbb8b2 ("KVM: arm64: GICv3: Detect and work around the lack of ICV_DIR_EL1 trapping")
---
 arch/arm64/kernel/cpufeature.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index d34dcc5630865..fb5665c6cea01 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -2325,16 +2325,16 @@ static bool can_trap_icv_dir_el1(const struct arm64_cpu_capabilities *entry,
 
 	BUILD_BUG_ON(ARM64_HAS_ICH_HCR_EL2_TDIR <= ARM64_HAS_GICV3_CPUIF);
 	BUILD_BUG_ON(ARM64_HAS_ICH_HCR_EL2_TDIR <= ARM64_HAS_GICV5_LEGACY);
-	if (!this_cpu_has_cap(ARM64_HAS_GICV3_CPUIF) &&
-	    !is_midr_in_range_list(has_vgic_v3))
-		return false;
-
 	if (!is_hyp_mode_available())
 		return false;
 
 	if (this_cpu_has_cap(ARM64_HAS_GICV5_LEGACY))
 		return true;
 
+	if (!this_cpu_has_cap(ARM64_HAS_GICV3_CPUIF) &&
+	    !is_midr_in_range_list(has_vgic_v3))
+		return false;
+
 	if (is_kernel_in_hyp_mode())
 		res.a1 = read_sysreg_s(SYS_ICH_VTR_EL2);
 	else
-- 
2.34.1