linux-kernel - [PATCH v3 04/18] x86/reboot: KVM: Disable SVM during reboot via virt/KVM reboot callback

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: <20230512235026.808058-5-seanjc@google.com>
Date:   Fri, 12 May 2023 16:50:12 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Andrew Cooper <Andrew.Cooper3@...rix.com>,
        Kai Huang <kai.huang@...el.com>, Chao Gao <chao.gao@...el.com>
Subject: [PATCH v3 04/18] x86/reboot: KVM: Disable SVM during reboot via
 virt/KVM reboot callback

Use the virt callback to disable SVM (and set GIF=1) during an emergency
instead of blindly attempting to disable SVM.  Like the VMX case, if a
hypervisor, i.e. KVM, isn't loaded/active, SVM can't be in use.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/include/asm/virtext.h |  8 --------
 arch/x86/kernel/reboot.c       |  3 ---
 arch/x86/kvm/svm/svm.c         | 19 +++++++++++++++++--
 3 files changed, 17 insertions(+), 13 deletions(-)

diff --git a/arch/x86/include/asm/virtext.h b/arch/x86/include/asm/virtext.h
index 5bc29fab15da..aaed66249ccf 100644
--- a/arch/x86/include/asm/virtext.h
+++ b/arch/x86/include/asm/virtext.h
@@ -133,12 +133,4 @@ static inline void cpu_svm_disable(void)
 	}
 }
 
-/** Makes sure SVM is disabled, if it is supported on the CPU
- */
-static inline void cpu_emergency_svm_disable(void)
-{
-	if (cpu_has_svm(NULL))
-		cpu_svm_disable();
-}
-
 #endif /* _ASM_X86_VIRTEX_H */
diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index 0cf2261c2dec..92b380e199a3 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -826,9 +826,6 @@ void cpu_emergency_disable_virtualization(void)
 	if (callback)
 		callback();
 	rcu_read_unlock();
-
-	/* KVM_AMD doesn't yet utilize the common callback. */
-	cpu_emergency_svm_disable();
 }
 
 #if defined(CONFIG_SMP)
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index eb308c9994f9..0f0d04900bf2 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -38,6 +38,7 @@
 #include <asm/spec-ctrl.h>
 #include <asm/cpu_device_id.h>
 #include <asm/traps.h>
+#include <asm/reboot.h>
 #include <asm/fpu/api.h>
 
 #include <asm/virtext.h>
@@ -568,6 +569,11 @@ void __svm_write_tsc_multiplier(u64 multiplier)
 	preempt_enable();
 }
 
+static void svm_emergency_disable(void)
+{
+	cpu_svm_disable();
+}
+
 static void svm_hardware_disable(void)
 {
 	/* Make sure we clean up behind us */
@@ -5184,6 +5190,13 @@ static struct kvm_x86_init_ops svm_init_ops __initdata = {
 	.pmu_ops = &amd_pmu_ops,
 };
 
+static void __svm_exit(void)
+{
+	kvm_x86_vendor_exit();
+
+	cpu_emergency_unregister_virt_callback(svm_emergency_disable);
+}
+
 static int __init svm_init(void)
 {
 	int r;
@@ -5197,6 +5210,8 @@ static int __init svm_init(void)
 	if (r)
 		return r;
 
+	cpu_emergency_register_virt_callback(svm_emergency_disable);
+
 	/*
 	 * Common KVM initialization _must_ come last, after this, /dev/kvm is
 	 * exposed to userspace!
@@ -5209,14 +5224,14 @@ static int __init svm_init(void)
 	return 0;
 
 err_kvm_init:
-	kvm_x86_vendor_exit();
+	__svm_exit();
 	return r;
 }
 
 static void __exit svm_exit(void)
 {
 	kvm_exit();
-	kvm_x86_vendor_exit();
+	__svm_exit();
 }
 
 module_init(svm_init)
-- 
2.40.1.606.ga4b1b128d6-goog