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From: Sean Christopherson <seanjc@google.com>
To: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org
Cc: "H. Peter Anvin" <hpa@zytor.com>,
	linux-kernel@vger.kernel.org,
	"Guilherme G . Piccoli" <gpiccoli@igalia.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Sean Christopherson <seanjc@google.com>,
	Andrew Cooper <Andrew.Cooper3@citrix.com>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	stable@vger.kernel
Subject: [PATCH v4 4/4] x86/reboot: Disable SVM, not just VMX, when stopping CPUs
Date: Wed, 30 Nov 2022 23:36:50 +0000	[thread overview]
Message-ID: <20221130233650.1404148-5-seanjc@google.com> (raw)
In-Reply-To: <20221130233650.1404148-1-seanjc@google.com>

Disable SVM and more importantly force GIF=1 when halting a CPU or
rebooting the machine.  Similar to VMX, SVM allows software to block
INITs via CLGI, and thus can be problematic for a crash/reboot.  The
window for failure is smaller with SVM as INIT is only blocked while
GIF=0, i.e. between CLGI and STGI, but the window does exist.

Fixes: fba4f472b33a ("x86/reboot: Turn off KVM when halting a CPU")
Cc: stable@vger.kernel
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kernel/smp.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c
index 06db901fabe8..375b33ecafa2 100644
--- a/arch/x86/kernel/smp.c
+++ b/arch/x86/kernel/smp.c
@@ -32,7 +32,7 @@
 #include <asm/mce.h>
 #include <asm/trace/irq_vectors.h>
 #include <asm/kexec.h>
-#include <asm/virtext.h>
+#include <asm/reboot.h>
 
 /*
  *	Some notes on x86 processor bugs affecting SMP operation:
@@ -122,7 +122,7 @@ static int smp_stop_nmi_callback(unsigned int val, struct pt_regs *regs)
 	if (raw_smp_processor_id() == atomic_read(&stopping_cpu))
 		return NMI_HANDLED;
 
-	cpu_emergency_vmxoff();
+	cpu_emergency_disable_virtualization();
 	stop_this_cpu(NULL);
 
 	return NMI_HANDLED;
@@ -134,7 +134,7 @@ static int smp_stop_nmi_callback(unsigned int val, struct pt_regs *regs)
 DEFINE_IDTENTRY_SYSVEC(sysvec_reboot)
 {
 	ack_APIC_irq();
-	cpu_emergency_vmxoff();
+	cpu_emergency_disable_virtualization();
 	stop_this_cpu(NULL);
 }
 
-- 
2.38.1.584.g0f3c55d4c2-goog


  parent reply	other threads:[~2022-11-30 23:37 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-30 23:36 [PATCH v4 0/4] x86/crash: Fix double NMI shootdown bug Sean Christopherson
2022-11-30 23:36 ` [PATCH v4 1/4] x86/crash: Disable virt in core NMI crash handler to avoid double shootdown Sean Christopherson
2022-11-30 23:36 ` [PATCH v4 2/4] x86/virt: Force GIF=1 prior to disabling SVM (for reboot flows) Sean Christopherson
2022-12-01 22:46   ` Andrew Cooper
2022-12-01 23:04     ` Sean Christopherson
2022-12-02  0:08       ` Andrew Cooper
2022-11-30 23:36 ` [PATCH v4 3/4] x86/reboot: Disable virtualization in an emergency if SVM is supported Sean Christopherson
2022-11-30 23:36 ` Sean Christopherson [this message]
2022-11-30 23:38   ` [PATCH v4 4/4] x86/reboot: Disable SVM, not just VMX, when stopping CPUs Sean Christopherson
2022-12-02 17:10 ` [PATCH v4 0/4] x86/crash: Fix double NMI shootdown bug Thomas Gleixner
2023-01-28  0:05 ` Sean Christopherson
2023-01-28 14:52   ` Guilherme G. Piccoli

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