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KVM: VMX: fix crash cleanup when KVM wasn't used 

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: 31603d4fc2 ("KVM: VMX: Always VMCLEAR in-use VMCSes during crash with kexec support")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200401081348.1345307-1-vkuznets@redhat.com>
Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Vitaly Kuznetsov 2020-04-01 10:13:48 +02:00 committed by Paolo Bonzini
parent 4064a4c6a1
commit dbef2808af
1 changed files with 7 additions and 5 deletions
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12
arch/x86/kvm/vmx/vmx.c
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@ -2261,10 +2261,6 @@ static int hardware_enable(void)
!hv_get_vp_assist_page(cpu))
return -EFAULT;
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));
r = kvm_cpu_vmxon(phys_addr);
if (r)
return r;
@ -8044,7 +8040,7 @@ module_exit(vmx_exit);
static int __init vmx_init(void)
{
int r;
int r, cpu;
#if IS_ENABLED(CONFIG_HYPERV)
/*
@ -8098,6 +8094,12 @@ static int __init vmx_init(void)
return r;
}
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);