90 lines
2.9 KiB
Diff
90 lines
2.9 KiB
Diff
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From: Andy Honig <ahonig@google.com>
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Date: Fri, 24 Oct 2014 17:07:13 +0200
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Subject: [PATCH] KVM: x86: Prevent host from panicking on shared MSR writes.
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The previous patch blocked invalid writes directly when the MSR
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is written. As a precaution, prevent future similar mistakes by
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gracefulling handle GPs caused by writes to shared MSRs.
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Cc: stable@vger.kernel.org
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Signed-off-by: Andrew Honig <ahonig@google.com>
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[Remove parts obsoleted by Nadav's patch. - Paolo]
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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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---
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arch/x86/include/asm/kvm_host.h | 2 +-
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arch/x86/kvm/vmx.c | 7 +++++--
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arch/x86/kvm/x86.c | 11 ++++++++---
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3 files changed, 14 insertions(+), 6 deletions(-)
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diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
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index ccc94de4ac49..6ed0c30d6a0c 100644
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--- a/arch/x86/include/asm/kvm_host.h
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+++ b/arch/x86/include/asm/kvm_host.h
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@@ -1064,7 +1064,7 @@ void kvm_arch_mmu_notifier_invalidate_page(struct kvm *kvm,
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unsigned long address);
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void kvm_define_shared_msr(unsigned index, u32 msr);
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-void kvm_set_shared_msr(unsigned index, u64 val, u64 mask);
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+int kvm_set_shared_msr(unsigned index, u64 val, u64 mask);
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bool kvm_is_linear_rip(struct kvm_vcpu *vcpu, unsigned long linear_rip);
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diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
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index 148020a7dd98..7e2c098b59c9 100644
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--- a/arch/x86/kvm/vmx.c
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+++ b/arch/x86/kvm/vmx.c
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@@ -2659,12 +2659,15 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
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default:
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msr = find_msr_entry(vmx, msr_index);
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if (msr) {
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+ u64 old_msr_data = msr->data;
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msr->data = data;
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if (msr - vmx->guest_msrs < vmx->save_nmsrs) {
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preempt_disable();
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- kvm_set_shared_msr(msr->index, msr->data,
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- msr->mask);
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+ ret = kvm_set_shared_msr(msr->index, msr->data,
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+ msr->mask);
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preempt_enable();
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+ if (ret)
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+ msr->data = old_msr_data;
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}
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break;
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}
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diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
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index 5a7195573a32..0033df32a745 100644
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--- a/arch/x86/kvm/x86.c
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+++ b/arch/x86/kvm/x86.c
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@@ -229,20 +229,25 @@ static void kvm_shared_msr_cpu_online(void)
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shared_msr_update(i, shared_msrs_global.msrs[i]);
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}
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-void kvm_set_shared_msr(unsigned slot, u64 value, u64 mask)
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+int kvm_set_shared_msr(unsigned slot, u64 value, u64 mask)
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{
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unsigned int cpu = smp_processor_id();
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struct kvm_shared_msrs *smsr = per_cpu_ptr(shared_msrs, cpu);
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+ int err;
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if (((value ^ smsr->values[slot].curr) & mask) == 0)
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- return;
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+ return 0;
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smsr->values[slot].curr = value;
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- wrmsrl(shared_msrs_global.msrs[slot], value);
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+ err = wrmsrl_safe(shared_msrs_global.msrs[slot], value);
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+ if (err)
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+ return 1;
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+
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if (!smsr->registered) {
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smsr->urn.on_user_return = kvm_on_user_return;
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user_return_notifier_register(&smsr->urn);
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smsr->registered = true;
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}
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+ return 0;
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}
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EXPORT_SYMBOL_GPL(kvm_set_shared_msr);
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--
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1.9.3
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