diff options
| author | Sean Christopherson <seanjc@google.com> | 2023-07-21 13:18:47 -0700 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2023-08-03 15:37:14 -0700 |
| commit | 59765db5fc82726b32876b794667e2c6936a98ab (patch) | |
| tree | bf4fb5cc3b84afe13f2059fe8468da0ebf425f20 /arch/x86/kernel/reboot.c | |
| parent | edc8deb087d884bac2f7013f0c23af73042b23a7 (diff) | |
x86/reboot: Disable virtualization during reboot iff callback is registered
Attempt to disable virtualization during an emergency reboot if and only
if there is a registered virt callback, i.e. iff a hypervisor (KVM) is
active. If there's no active hypervisor, then the CPU can't be operating
with VMX or SVM enabled (barring an egregious bug).
Checking for a valid callback instead of simply for SVM or VMX support
can also eliminates spurious NMIs by avoiding the unecessary call to
nmi_shootdown_cpus_on_restart().
Note, IRQs are disabled, which prevents KVM from coming along and
enabling virtualization after the fact.
Reviewed-by: Kai Huang <kai.huang@intel.com>
Link: https://lore.kernel.org/r/20230721201859.2307736-8-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Diffstat (limited to 'arch/x86/kernel/reboot.c')
| -rw-r--r-- | arch/x86/kernel/reboot.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c index 85cb2dfcb67b..98e5db3fd7f4 100644 --- a/arch/x86/kernel/reboot.c +++ b/arch/x86/kernel/reboot.c @@ -22,7 +22,6 @@ #include <asm/reboot_fixups.h> #include <asm/reboot.h> #include <asm/pci_x86.h> -#include <asm/virtext.h> #include <asm/cpu.h> #include <asm/nmi.h> #include <asm/smp.h> @@ -589,7 +588,7 @@ static void emergency_reboot_disable_virtualization(void) * Do the NMI shootdown even if virtualization is off on _this_ CPU, as * other CPUs may have virtualization enabled. */ - if (cpu_has_vmx() || cpu_has_svm(NULL)) { + if (rcu_access_pointer(cpu_emergency_virt_callback)) { /* Safely force _this_ CPU out of VMX/SVM operation. */ cpu_emergency_disable_virtualization(); |