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| author | Andre Przywara <andre.przywara@amd.com> | 2009-06-25 12:36:49 +0200 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2009-09-10 08:33:03 +0300 |
| commit | ed85c0685321a139cefd6622b21467643f0159e1 (patch) | |
| tree | eb1470a8a736886fd563b02aecbc608b4dd16d54 /arch | |
| parent | 1fdbd48c242db996107f72ae4140ffe8163e26a8 (diff) | |
KVM: introduce module parameter for ignoring unknown MSRs accesses
KVM will inject a #GP into the guest if that tries to access unhandled
MSRs. This will crash many guests. Although it would be the correct
way to actually handle these MSRs, we introduce a runtime switchable
module param called "ignore_msrs" (defaults to 0). If this is Y, unknown
MSR reads will return 0, while MSR writes are simply dropped. In both cases
we print a message to dmesg to inform the user about that.
You can change the behaviour at any time by saying:
# echo 1 > /sys/modules/kvm/parameters/ignore_msrs
Signed-off-by: Andre Przywara <andre.przywara@amd.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kvm/x86.c | 24 |
1 files changed, 20 insertions, 4 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 6aace61fdb62..0be75d53b7fd 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -83,6 +83,9 @@ struct kvm_cpuid_entry2 *kvm_find_cpuid_entry(struct kvm_vcpu *vcpu, struct kvm_x86_ops *kvm_x86_ops; EXPORT_SYMBOL_GPL(kvm_x86_ops); +int ignore_msrs = 0; +module_param_named(ignore_msrs, ignore_msrs, bool, S_IRUGO | S_IWUSR); + struct kvm_stats_debugfs_item debugfs_entries[] = { { "pf_fixed", VCPU_STAT(pf_fixed) }, { "pf_guest", VCPU_STAT(pf_guest) }, @@ -930,8 +933,15 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data) "0x%x data 0x%llx\n", msr, data); break; default: - pr_unimpl(vcpu, "unhandled wrmsr: 0x%x data %llx\n", msr, data); - return 1; + if (!ignore_msrs) { + pr_unimpl(vcpu, "unhandled wrmsr: 0x%x data %llx\n", + msr, data); + return 1; + } else { + pr_unimpl(vcpu, "ignored wrmsr: 0x%x data %llx\n", + msr, data); + break; + } } return 0; } @@ -1078,8 +1088,14 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata) case MSR_IA32_MC0_CTL ... MSR_IA32_MC0_CTL + 4 * KVM_MAX_MCE_BANKS - 1: return get_msr_mce(vcpu, msr, pdata); default: - pr_unimpl(vcpu, "unhandled rdmsr: 0x%x\n", msr); - return 1; + if (!ignore_msrs) { + pr_unimpl(vcpu, "unhandled rdmsr: 0x%x\n", msr); + return 1; + } else { + pr_unimpl(vcpu, "ignored rdmsr: 0x%x\n", msr); + data = 0; + } + break; } *pdata = data; return 0; |