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

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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>
This commit is contained in:
Andy Honig
2014-08-27 11:16:44 -07:00
committed by Paolo Bonzini
parent 854e8bb1aa
commit 8b3c3104c3
3 changed files with 14 additions and 6 deletions
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11
arch/x86/kvm/x86.c
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@@ -229,20 +229,25 @@ 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);