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authorPaolo Bonzini <pbonzini@redhat.com>2021-11-12 02:53:41 -0500
committerPaolo Bonzini <pbonzini@redhat.com>2021-11-12 02:53:52 -0500
commit3e067fd8503d6205aa0c1c8f48f6b209c592d19c (patch)
treee2823b5d7c2e3d740f9ecb810ddfff9ad6d7896a /arch/x86
parentf5396f2d826823b16de5d2cef6f46ffc66712482 (diff)
downloadlinux-3e067fd8503d6205aa0c1c8f48f6b209c592d19c.tar.gz
KVM: x86: move guest_pv_has out of user_access section
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>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/kvm/x86.c9
1 files changed, 6 insertions, 3 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index dd7b8b465675..dc7eb5fddfd3 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3292,9 +3292,6 @@ 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.
@@ -3303,6 +3300,9 @@ 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"
@@ -3325,6 +3325,9 @@ 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;
 	}