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    Subject[PATCH 5.15 857/917] KVM: x86: move guest_pv_has out of user_access section
    Date
    From: Paolo Bonzini <pbonzini@redhat.com>

    commit 3e067fd8503d6205aa0c1c8f48f6b209c592d19c upstream.

    When UBSAN is enabled, the code emitted for the call to guest_pv_has
    includes a call to __ubsan_handle_load_invalid_value. objtool
    complains that this call happens with UACCESS enabled; to avoid
    the warning, pull the calls to user_access_begin into both arms
    of the "if" statement, after the check for guest_pv_has.

    Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
    Cc: David Woodhouse <dwmw2@infradead.org>
    Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    arch/x86/kvm/x86.c | 9 ++++++---
    1 file changed, 6 insertions(+), 3 deletions(-)

    --- a/arch/x86/kvm/x86.c
    +++ b/arch/x86/kvm/x86.c
    @@ -3227,9 +3227,6 @@ static void record_steal_time(struct kvm
    }

    st = (struct kvm_steal_time __user *)ghc->hva;
    - if (!user_access_begin(st, sizeof(*st)))
    - return;
    -
    /*
    * Doing a TLB flush here, on the guest's behalf, can avoid
    * expensive IPIs.
    @@ -3238,6 +3235,9 @@ static void record_steal_time(struct kvm
    u8 st_preempted = 0;
    int err = -EFAULT;

    + if (!user_access_begin(st, sizeof(*st)))
    + return;
    +
    asm volatile("1: xchgb %0, %2\n"
    "xor %1, %1\n"
    "2:\n"
    @@ -3260,6 +3260,9 @@ static void record_steal_time(struct kvm
    if (!user_access_begin(st, sizeof(*st)))
    goto dirty;
    } else {
    + if (!user_access_begin(st, sizeof(*st)))
    + return;
    +
    unsafe_put_user(0, &st->preempted, out);
    vcpu->arch.st.preempted = 0;
    }

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