KVM: x86: move guest_pv_has out of user_access section

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>

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 2a1fc0fe9422171f74f49065daadd5bb86d7f77a..285e8659314368bf5d6399e9c71ea12ca4ec3e46 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3222,9 +3222,6 @@ static void record_steal_time(struct kvm_vcpu *vcpu)
        }
 
        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.
@@ -3233,6 +3230,9 @@ static void record_steal_time(struct kvm_vcpu *vcpu)
                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"
@@ -3255,6 +3255,9 @@ static void record_steal_time(struct kvm_vcpu *vcpu)
                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;
        }