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    Subject[PATCH 5.4 218/309] x86/KVM: Clean up hosts steal time structure
    Date
    From: Boris Ostrovsky <boris.ostrovsky@oracle.com>

    commit a6bd811f1209fe1c64c9f6fd578101d6436c6b6e upstream.

    Now that we are mapping kvm_steal_time from the guest directly we
    don't need keep a copy of it in kvm_vcpu_arch.st. The same is true
    for the stime field.

    This is part of CVE-2019-3016.

    Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
    Reviewed-by: Joao Martins <joao.m.martins@oracle.com>
    Cc: stable@vger.kernel.org
    Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    arch/x86/include/asm/kvm_host.h | 3 +--
    arch/x86/kvm/x86.c | 11 +++--------
    2 files changed, 4 insertions(+), 10 deletions(-)

    --- a/arch/x86/include/asm/kvm_host.h
    +++ b/arch/x86/include/asm/kvm_host.h
    @@ -667,10 +667,9 @@ struct kvm_vcpu_arch {
    bool pvclock_set_guest_stopped_request;

    struct {
    + u8 preempted;
    u64 msr_val;
    u64 last_steal;
    - struct gfn_to_hva_cache stime;
    - struct kvm_steal_time steal;
    struct gfn_to_pfn_cache cache;
    } st;

    --- a/arch/x86/kvm/x86.c
    +++ b/arch/x86/kvm/x86.c
    @@ -2616,7 +2616,7 @@ static void record_steal_time(struct kvm
    if (xchg(&st->preempted, 0) & KVM_VCPU_FLUSH_TLB)
    kvm_vcpu_flush_tlb(vcpu, false);

    - vcpu->arch.st.steal.preempted = 0;
    + vcpu->arch.st.preempted = 0;

    if (st->version & 1)
    st->version += 1; /* first time write, random junk */
    @@ -2786,11 +2786,6 @@ int kvm_set_msr_common(struct kvm_vcpu *
    if (data & KVM_STEAL_RESERVED_MASK)
    return 1;

    - if (kvm_gfn_to_hva_cache_init(vcpu->kvm, &vcpu->arch.st.stime,
    - data & KVM_STEAL_VALID_BITS,
    - sizeof(struct kvm_steal_time)))
    - return 1;
    -
    vcpu->arch.st.msr_val = data;

    if (!(data & KVM_MSR_ENABLED))
    @@ -3504,7 +3499,7 @@ static void kvm_steal_time_set_preempted
    if (!(vcpu->arch.st.msr_val & KVM_MSR_ENABLED))
    return;

    - if (vcpu->arch.st.steal.preempted)
    + if (vcpu->arch.st.preempted)
    return;

    if (kvm_map_gfn(vcpu, vcpu->arch.st.msr_val >> PAGE_SHIFT, &map,
    @@ -3514,7 +3509,7 @@ static void kvm_steal_time_set_preempted
    st = map.hva +
    offset_in_page(vcpu->arch.st.msr_val & KVM_STEAL_VALID_BITS);

    - st->preempted = vcpu->arch.st.steal.preempted = KVM_VCPU_PREEMPTED;
    + st->preempted = vcpu->arch.st.preempted = KVM_VCPU_PREEMPTED;

    kvm_unmap_gfn(vcpu, &map, &vcpu->arch.st.cache, true, true);
    }

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