From: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
commit dbef2808af6c594922fe32833b30f55f35e9da6d upstream.
If KVM wasn't used at all before we crash the cleanup procedure fails with
BUG: unable to handle page fault for address: ffffffffffffffc8
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 23215067 P4D 23215067 PUD 23217067 PMD 0
Oops: 0000 [#8] SMP PTI
CPU: 0 PID: 3542 Comm: bash Kdump: loaded Tainted: G D 5.6.0-rc2+ #823
RIP: 0010:crash_vmclear_local_loaded_vmcss.cold+0x19/0x51 [kvm_intel]
The root cause is that loaded_vmcss_on_cpu list is not yet initialized,
we initialize it in hardware_enable() but this only happens when we start
a VM.
Previously, we used to have a bitmap with enabled CPUs and that was
preventing [masking] the issue.
Initialized loaded_vmcss_on_cpu list earlier, right before we assign
crash_vmclear_loaded_vmcss pointer. blocked_vcpu_on_cpu list and
blocked_vcpu_on_cpu_lock are moved altogether for consistency.
Fixes: 31603d4fc2bb ("KVM: VMX: Always VMCLEAR in-use VMCSes during crash with kexec support")
Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
Message-Id: <20200401081348.1345307-1-vkuznets@xxxxxxxxxx>
Reviewed-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/vmx.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3482,10 +3482,6 @@ static int hardware_enable(void)
if (cr4_read_shadow() & X86_CR4_VMXE)
return -EBUSY;
- INIT_LIST_HEAD(&per_cpu(loaded_vmcss_on_cpu, cpu));
- INIT_LIST_HEAD(&per_cpu(blocked_vcpu_on_cpu, cpu));
- spin_lock_init(&per_cpu(blocked_vcpu_on_cpu_lock, cpu));
-
rdmsrl(MSR_IA32_FEATURE_CONTROL, old);
test_bits = FEATURE_CONTROL_LOCKED;
@@ -11860,7 +11856,7 @@ module_exit(vmx_exit)
static int __init vmx_init(void)
{
- int r;
+ int r, cpu;
r = kvm_init(&vmx_x86_ops, sizeof(struct vcpu_vmx),
__alignof__(struct vcpu_vmx), THIS_MODULE);
@@ -11882,6 +11878,12 @@ static int __init vmx_init(void)
}
}
+ for_each_possible_cpu(cpu) {
+ INIT_LIST_HEAD(&per_cpu(loaded_vmcss_on_cpu, cpu));
+ INIT_LIST_HEAD(&per_cpu(blocked_vcpu_on_cpu, cpu));
+ spin_lock_init(&per_cpu(blocked_vcpu_on_cpu_lock, cpu));
+ }
+
#ifdef CONFIG_KEXEC_CORE
rcu_assign_pointer(crash_vmclear_loaded_vmcss,
crash_vmclear_local_loaded_vmcss);
