diff options
| author | Ben Serebrin <serebrin@google.com> | 2015-04-16 21:58:05 +0300 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2015-08-07 02:32:06 +0300 |
| commit | 330a80fdcee47ec8eb0a1a37edeaebdcf3720960 (patch) | |
| tree | db0d46a4ec6070e1ec41995c0be54e1262aa63c0 /arch | |
| parent | 0fd0b9f448e1ff459ea4f718def61a197b15bb4c (diff) | |
| download | linux-330a80fdcee47ec8eb0a1a37edeaebdcf3720960.tar.xz | |
KVM: VMX: Preserve host CR4.MCE value while in guest mode.
commit 085e68eeafbf76e21848ad5bafaecec88a11dd64 upstream.
The host's decision to enable machine check exceptions should remain
in force during non-root mode. KVM was writing 0 to cr4 on VCPU reset
and passed a slightly-modified 0 to the vmcs.guest_cr4 value.
Tested: Built.
On earlier version, tested by injecting machine check
while a guest is spinning.
Before the change, if guest CR4.MCE==0, then the machine check is
escalated to Catastrophic Error (CATERR) and the machine dies.
If guest CR4.MCE==1, then the machine check causes VMEXIT and is
handled normally by host Linux. After the change, injecting a machine
check causes normal Linux machine check handling.
Signed-off-by: Ben Serebrin <serebrin@google.com>
Reviewed-by: Venkatesh Srinivas <venkateshs@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
[bwh: Backported to 3.2: use read_cr4() instead of cr4_read_shadow()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kvm/vmx.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 8831c43efd11..421958f1b12e 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -3032,8 +3032,16 @@ static void vmx_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3) static int vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) { - unsigned long hw_cr4 = cr4 | (to_vmx(vcpu)->rmode.vm86_active ? - KVM_RMODE_VM_CR4_ALWAYS_ON : KVM_PMODE_VM_CR4_ALWAYS_ON); + /* + * Pass through host's Machine Check Enable value to hw_cr4, which + * is in force while we are in guest mode. Do not let guests control + * this bit, even if host CR4.MCE == 0. + */ + unsigned long hw_cr4 = + (read_cr4() & X86_CR4_MCE) | + (cr4 & ~X86_CR4_MCE) | + (to_vmx(vcpu)->rmode.vm86_active ? + KVM_RMODE_VM_CR4_ALWAYS_ON : KVM_PMODE_VM_CR4_ALWAYS_ON); if (cr4 & X86_CR4_VMXE) { /* |