linux-kernel - [PATCH v2 3/4] KVM: SVM: Don't advertise Bus Lock Detect to guest if SVM support is missing

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: <20240712093943.1288-4-ravi.bangoria@amd.com>
Date: Fri, 12 Jul 2024 09:39:42 +0000
From: Ravi Bangoria <ravi.bangoria@....com>
To: <tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>,
	<dave.hansen@...ux.intel.com>, <seanjc@...gle.com>, <pbonzini@...hat.com>,
	<thomas.lendacky@....com>
CC: <ravi.bangoria@....com>, <hpa@...or.com>, <rmk+kernel@...linux.org.uk>,
	<peterz@...radead.org>, <james.morse@....com>, <lukas.bulwahn@...il.com>,
	<arjan@...ux.intel.com>, <j.granados@...sung.com>, <sibs@...natelecom.cn>,
	<nik.borisov@...e.com>, <michael.roth@....com>, <nikunj.dadhania@....com>,
	<babu.moger@....com>, <x86@...nel.org>, <kvm@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <santosh.shukla@....com>,
	<ananth.narayan@....com>, <sandipan.das@....com>, <manali.shukla@....com>,
	<jmattson@...gle.com>
Subject: [PATCH v2 3/4] KVM: SVM: Don't advertise Bus Lock Detect to guest if SVM support is missing

If host supports Bus Lock Detect, KVM advertises it to guests even if
SVM support is absent. Additionally, guest wouldn't be able to use it
despite guest CPUID bit being set. Fix it by unconditionally clearing
the feature bit in KVM cpu capability.

Reported-by: Jim Mattson <jmattson@...gle.com>
Closes: https://lore.kernel.org/r/CALMp9eRet6+v8Y1Q-i6mqPm4hUow_kJNhmVHfOV8tMfuSS=tVg@mail.gmail.com
Fixes: 76ea438b4afc ("KVM: X86: Expose bus lock debug exception to guest")
Cc: stable@...r.kernel.org
Signed-off-by: Ravi Bangoria <ravi.bangoria@....com>
---
 arch/x86/kvm/svm/svm.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index c95d3900fe56..4a1d0a8478a5 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -5211,6 +5211,9 @@ static __init void svm_set_cpu_caps(void)
 
 	/* CPUID 0x8000001F (SME/SEV features) */
 	sev_set_cpu_caps();
+
+	/* Don't advertise Bus Lock Detect to guest if SVM support is absent */
+	kvm_cpu_cap_clear(X86_FEATURE_BUS_LOCK_DETECT);
 }
 
 static __init int svm_hardware_setup(void)
-- 
2.34.1