linux-kernel - [PATCH v16 5/6] KVM: arm64: Allow GCS to be enabled for guests

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20250912-arm64-gcs-v16-5-6435e5ec37db@kernel.org>
Date: Fri, 12 Sep 2025 10:25:31 +0100
From: Mark Brown <broonie@...nel.org>
To: Catalin Marinas <catalin.marinas@....com>, 
 Will Deacon <will@...nel.org>, Marc Zyngier <maz@...nel.org>, 
 Oliver Upton <oliver.upton@...ux.dev>, Joey Gouly <joey.gouly@....com>, 
 Suzuki K Poulose <suzuki.poulose@....com>, Shuah Khan <shuah@...nel.org>
Cc: linux-arm-kernel@...ts.infradead.org, linux-doc@...r.kernel.org, 
 kvmarm@...ts.linux.dev, linux-kselftest@...r.kernel.org, 
 linux-kernel@...r.kernel.org, Mark Brown <broonie@...nel.org>
Subject: [PATCH v16 5/6] KVM: arm64: Allow GCS to be enabled for guests

Now that required functionality for GCS is in place expose
ID_AA64PFR1_EL1.GCS, allowing guests to be given the feature.

Signed-off-by: Mark Brown <broonie@...nel.org>
---
 arch/arm64/kvm/nested.c   | 7 ++++---
 arch/arm64/kvm/sys_regs.c | 2 --
 2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c
index 153b3e11b115..d2d55e18c610 100644
--- a/arch/arm64/kvm/nested.c
+++ b/arch/arm64/kvm/nested.c
@@ -1459,9 +1459,10 @@ u64 limit_nv_id_reg(struct kvm *kvm, u32 reg, u64 val)
 
 	case SYS_ID_AA64PFR1_EL1:
 		/* Only support BTI, SSBS, CSV2_frac */
-		val &= (ID_AA64PFR1_EL1_BT	|
-			ID_AA64PFR1_EL1_SSBS	|
-			ID_AA64PFR1_EL1_CSV2_frac);
+		val &= (ID_AA64PFR1_EL1_BT		|
+			ID_AA64PFR1_EL1_SSBS		|
+			ID_AA64PFR1_EL1_CSV2_frac	|
+			ID_AA64PFR1_EL1_GCS);
 		break;
 
 	case SYS_ID_AA64MMFR0_EL1:
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 03fb2dce0b80..60e234422064 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1616,7 +1616,6 @@ static u64 __kvm_read_sanitised_id_reg(const struct kvm_vcpu *vcpu,
 		val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_SME);
 		val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_RNDR_trap);
 		val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_NMI);
-		val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_GCS);
 		val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_THE);
 		val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_MTEX);
 		val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_PFAR);
@@ -2953,7 +2952,6 @@ static const struct sys_reg_desc sys_reg_descs[] = {
 				     ~(ID_AA64PFR1_EL1_PFAR |
 				       ID_AA64PFR1_EL1_MTEX |
 				       ID_AA64PFR1_EL1_THE |
-				       ID_AA64PFR1_EL1_GCS |
 				       ID_AA64PFR1_EL1_MTE_frac |
 				       ID_AA64PFR1_EL1_NMI |
 				       ID_AA64PFR1_EL1_RNDR_trap |

-- 
2.47.2