diff options
| author | Andy Honig <ahonig@google.com> | 2014-08-27 11:16:44 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-11-14 08:59:54 -0800 |
| commit | fb07a1411e604987d1ca415d33aa16c1a22702bc (patch) | |
| tree | 68f87c1de6690fd0856eda4ca94cc9ee712dde64 | |
| parent | 8c373cfce6904feccca7ccf2a61e236db56dedf4 (diff) | |
| download | lwn-fb07a1411e604987d1ca415d33aa16c1a22702bc.tar.gz lwn-fb07a1411e604987d1ca415d33aa16c1a22702bc.zip | |
KVM: x86: Prevent host from panicking on shared MSR writes.
commit 8b3c3104c3f4f706e99365c3e0d2aa61b95f969f upstream.
The previous patch blocked invalid writes directly when the MSR
is written. As a precaution, prevent future similar mistakes by
gracefulling handle GPs caused by writes to shared MSRs.
Signed-off-by: Andrew Honig <ahonig@google.com>
[Remove parts obsoleted by Nadav's patch. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/x86/include/asm/kvm_host.h | 2 | ||||
| -rw-r--r-- | arch/x86/kvm/vmx.c | 7 | ||||
| -rw-r--r-- | arch/x86/kvm/x86.c | 11 |
3 files changed, 14 insertions, 6 deletions
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index ac63ea4af5b0..cffcaee5425d 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1042,7 +1042,7 @@ int kvm_cpu_get_interrupt(struct kvm_vcpu *v); void kvm_vcpu_reset(struct kvm_vcpu *vcpu); void kvm_define_shared_msr(unsigned index, u32 msr); -void kvm_set_shared_msr(unsigned index, u64 val, u64 mask); +int kvm_set_shared_msr(unsigned index, u64 val, u64 mask); bool kvm_is_linear_rip(struct kvm_vcpu *vcpu, unsigned long linear_rip); diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 392752834751..75baf927be99 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -2582,12 +2582,15 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) default: msr = find_msr_entry(vmx, msr_index); if (msr) { + u64 old_msr_data = msr->data; msr->data = data; if (msr - vmx->guest_msrs < vmx->save_nmsrs) { preempt_disable(); - kvm_set_shared_msr(msr->index, msr->data, - msr->mask); + ret = kvm_set_shared_msr(msr->index, msr->data, + msr->mask); preempt_enable(); + if (ret) + msr->data = old_msr_data; } break; } diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 8fbd1a772272..dc1ee99cfc6d 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -225,20 +225,25 @@ static void kvm_shared_msr_cpu_online(void) shared_msr_update(i, shared_msrs_global.msrs[i]); } -void kvm_set_shared_msr(unsigned slot, u64 value, u64 mask) +int kvm_set_shared_msr(unsigned slot, u64 value, u64 mask) { unsigned int cpu = smp_processor_id(); struct kvm_shared_msrs *smsr = per_cpu_ptr(shared_msrs, cpu); + int err; if (((value ^ smsr->values[slot].curr) & mask) == 0) - return; + return 0; smsr->values[slot].curr = value; - wrmsrl(shared_msrs_global.msrs[slot], value); + err = wrmsrl_safe(shared_msrs_global.msrs[slot], value); + if (err) + return 1; + if (!smsr->registered) { smsr->urn.on_user_return = kvm_on_user_return; user_return_notifier_register(&smsr->urn); smsr->registered = true; } + return 0; } EXPORT_SYMBOL_GPL(kvm_set_shared_msr); |