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Received-SPF: Pass (protection.outlook.com: domain of amd.com designates 165.204.84.17 as permitted sender) receiver=protection.outlook.com; client-ip=165.204.84.17; helo=satlexmb07.amd.com; pr=C Received: from satlexmb07.amd.com (165.204.84.17) by BN7PEPF0000009E.mail.protection.outlook.com (10.167.248.150) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.451.8 via Frontend Transport; Fri, 25 Sep 2026 11:45:34 +0000 Received: from purico-abeahost.amd.com (10.180.168.240) by satlexmb07.amd.com (10.181.42.216) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.49; Fri, 25 Sep 2026 06:45:28 -0500 From: Shivansh Dhiman To: , , , CC: , , , , , , , , , , , , , Subject: [PATCH v3 9/9] KVM: SVM: Don't intercept ICEBP while the guest has FRED enabled Date: Fri, 25 Sep 2026 11:40:17 +0000 Message-ID: <20260925114017.2208531-10-shivansh.dhiman@amd.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260925114017.2208531-1-shivansh.dhiman@amd.com> References: <20260925114017.2208531-1-shivansh.dhiman@amd.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: satlexmb07.amd.com (10.181.42.216) To satlexmb07.amd.com (10.181.42.216) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BN7PEPF0000009E:EE_|DS6PR12MB381293:EE_ X-MS-Office365-Filtering-Correlation-Id: 63b80a9b-37d4-4994-e83a-08df1afa8273 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|36860700016|23010399003|376014|7416014|82310400026|1800799024|56012099006|11063799006|10067099003|18002099003|22082099003|3023799007; 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A FRED guest therefore sees INT1 as event type 3 instead of 5. FRED has no task gates, so the workaround isn't needed while CR4.FRED is set. Stop intercepting ICEBP while CR4.FRED is set, and recalculate the intercepts whenever svm_set_cr4() changes CR4.FRED. Signed-off-by: Shivansh Dhiman --- Changes in v3: * New patch. --- arch/x86/kvm/svm/svm.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 25dd379725d4..9b2cab844823 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -1137,6 +1137,11 @@ static void svm_recalc_instruction_intercepts(struct kvm_vcpu *vcpu) svm_set_intercept(svm, INTERCEPT_RDPMC); else svm_clr_intercept(svm, INTERCEPT_RDPMC); + + if (is_fred_enabled(vcpu)) + svm_clr_intercept(svm, INTERCEPT_ICEBP); + else + svm_set_intercept(svm, INTERCEPT_ICEBP); } static void svm_recalc_intercepts(struct kvm_vcpu *vcpu) @@ -1911,6 +1916,9 @@ void svm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) if ((cr4 ^ old_cr4) & (X86_CR4_OSXSAVE | X86_CR4_PKE)) vcpu->arch.cpuid_dynamic_bits_dirty = true; + + if ((cr4 ^ old_cr4) & X86_CR4_FRED) + kvm_make_request(KVM_REQ_RECALC_INTERCEPTS, vcpu); } static void svm_set_segment(struct kvm_vcpu *vcpu, -- 2.43.0