Eric Lee / smarc-ti-linux-kernel

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Commit 8b3c3104c3f4f706e99365c3e0d2aa61b95f969f

Authored by Andy Honig
Committed by Paolo Bonzini
1 parent 854e8bb1aa
Exists in ti-lsk-linux-4.1.y and in 10 other branches dlt-processor-sdk-linux-03.00.00.04, processor-sdk-linux-02.00.01, smarc-ti-lsk-linux-4.1.y, smarct3x-processor-sdk-04.01.00.06, smarct3x-processor-sdk-linux-02.00.01, smarct3x-processor-sdk-linux-03.00.00.04, smarct4x-800-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-04.01.00.06, smarct4x-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-linux-03.00.00.04

KVM: x86: Prevent host from panicking on shared MSR writes. 

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.

Cc: stable@vger.kernel.org
Signed-off-by: Andrew Honig <ahonig@google.com>
[Remove parts obsoleted by Nadav's patch. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Showing 3 changed files with 14 additions and 6 deletions Side-by-side Diff

arch/x86/include/asm/kvm_host.h
Diff comments   View file @ 8b3c310
... ... @@ -1064,7 +1064,7 @@
1064 1064 unsigned long address);
1065 1065  
1066 1066 void kvm_define_shared_msr(unsigned index, u32 msr);
1067   -void kvm_set_shared_msr(unsigned index, u64 val, u64 mask);
  1067 +int kvm_set_shared_msr(unsigned index, u64 val, u64 mask);
1068 1068  
1069 1069 bool kvm_is_linear_rip(struct kvm_vcpu *vcpu, unsigned long linear_rip);
1070 1070  
... ... @@ -2659,12 +2659,15 @@
2659 2659 default:
2660 2660 msr = find_msr_entry(vmx, msr_index);
2661 2661 if (msr) {
  2662 + u64 old_msr_data = msr->data;
2662 2663 msr->data = data;
2663 2664 if (msr - vmx->guest_msrs < vmx->save_nmsrs) {
2664 2665 preempt_disable();
2665   - kvm_set_shared_msr(msr->index, msr->data,
2666   - msr->mask);
  2666 + ret = kvm_set_shared_msr(msr->index, msr->data,
  2667 + msr->mask);
2667 2668 preempt_enable();
  2669 + if (ret)
  2670 + msr->data = old_msr_data;
2668 2671 }
2669 2672 break;
2670 2673 }
... ... @@ -229,20 +229,25 @@
229 229 shared_msr_update(i, shared_msrs_global.msrs[i]);
230 230 }
231 231  
232   -void kvm_set_shared_msr(unsigned slot, u64 value, u64 mask)
  232 +int kvm_set_shared_msr(unsigned slot, u64 value, u64 mask)
233 233 {
234 234 unsigned int cpu = smp_processor_id();
235 235 struct kvm_shared_msrs *smsr = per_cpu_ptr(shared_msrs, cpu);
  236 + int err;
236 237  
237 238 if (((value ^ smsr->values[slot].curr) & mask) == 0)
238   - return;
  239 + return 0;
239 240 smsr->values[slot].curr = value;
240   - wrmsrl(shared_msrs_global.msrs[slot], value);
  241 + err = wrmsrl_safe(shared_msrs_global.msrs[slot], value);
  242 + if (err)
  243 + return 1;
  244 +
241 245 if (!smsr->registered) {
242 246 smsr->urn.on_user_return = kvm_on_user_return;
243 247 user_return_notifier_register(&smsr->urn);
244 248 smsr->registered = true;
245 249 }
  250 + return 0;
246 251 }
247 252 EXPORT_SYMBOL_GPL(kvm_set_shared_msr);
248 253