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: Rishabh Bhatnagar risbhat@amazon.com --- arch/x86/kvm/x86.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 9e9298c333c8..e3599a51c72d 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3042,9 +3042,6 @@ 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. @@ -3053,6 +3050,9 @@ 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" @@ -3075,6 +3075,9 @@ 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; }