diff options
| author | Jan H. Schönherr <jschoenh@amazon.de> | 2017-05-20 13:22:56 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2017-05-26 17:59:27 +0200 |
| commit | e1d39b17e044e8ae819827810d87d809ba5f58c0 (patch) | |
| tree | 6051dc367d678d3ecb89e770337cd9ab0a483838 /arch | |
| parent | 5acc1ca4fb15f00bfa3d4046e35ca381bc25d580 (diff) | |
KVM: nVMX: Fix handling of lmsw instruction
The decision whether or not to exit from L2 to L1 on an lmsw instruction is
based on bogus values: instead of using the information encoded within the
exit qualification, it uses the data also used for the mov-to-cr
instruction, which boils down to using whatever is in %eax at that point.
Use the correct values instead.
Without this fix, an L1 may not get notified when a 32-bit Linux L2
switches its secondary CPUs to protected mode; the L1 is only notified on
the next modification of CR0. This short time window poses a problem, when
there is some other reason to exit to L1 in between. Then, L2 will be
resumed in real mode and chaos ensues.
Signed-off-by: Jan H. Schönherr <jschoenh@amazon.de>
Reviewed-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kvm/vmx.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 72f78396bc09..880f371705bc 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -7913,11 +7913,13 @@ static bool nested_vmx_exit_handled_cr(struct kvm_vcpu *vcpu, { unsigned long exit_qualification = vmcs_readl(EXIT_QUALIFICATION); int cr = exit_qualification & 15; - int reg = (exit_qualification >> 8) & 15; - unsigned long val = kvm_register_readl(vcpu, reg); + int reg; + unsigned long val; switch ((exit_qualification >> 4) & 3) { case 0: /* mov to cr */ + reg = (exit_qualification >> 8) & 15; + val = kvm_register_readl(vcpu, reg); switch (cr) { case 0: if (vmcs12->cr0_guest_host_mask & @@ -7972,6 +7974,7 @@ static bool nested_vmx_exit_handled_cr(struct kvm_vcpu *vcpu, * lmsw can change bits 1..3 of cr0, and only set bit 0 of * cr0. Other attempted changes are ignored, with no exit. */ + val = (exit_qualification >> LMSW_SOURCE_DATA_SHIFT) & 0x0f; if (vmcs12->cr0_guest_host_mask & 0xe & (val ^ vmcs12->cr0_read_shadow)) return true; |