ppc/kvm: Replace ACCESS_ONCE with READ_ONCE

ACCESS_ONCE does not work reliably on non-scalar types. For
example gcc 4.6 and 4.7 might remove the volatile tag for such
accesses during the SRA (scalar replacement of aggregates) step
(https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145)

Change the ppc/kvm code to replace ACCESS_ONCE with READ_ONCE.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Alexander Graf <agraf@suse.de>

arch/powerpc/kvm/book3s_hv_rm_xics.c

@@ -152,7 +152,7 @@ static void icp_rm_down_cppr(struct kvmppc_xics *xics, struct kvmppc_icp *icp,
 	 * in virtual mode.
 	 */
 	do {
-		old_state = new_state = ACCESS_ONCE(icp->state);
+		old_state = new_state = READ_ONCE(icp->state);
 
 		/* Down_CPPR */
 		new_state.cppr = new_cppr;
@@ -211,7 +211,7 @@ unsigned long kvmppc_rm_h_xirr(struct kvm_vcpu *vcpu)
 	 * pending priority
 	 */
 	do {
-		old_state = new_state = ACCESS_ONCE(icp->state);
+		old_state = new_state = READ_ONCE(icp->state);
 
 		xirr = old_state.xisr | (((u32)old_state.cppr) << 24);
 		if (!old_state.xisr)
@@ -277,7 +277,7 @@ int kvmppc_rm_h_ipi(struct kvm_vcpu *vcpu, unsigned long server,
 	 * whenever the MFRR is made less favored.
 	 */
 	do {
-		old_state = new_state = ACCESS_ONCE(icp->state);
+		old_state = new_state = READ_ONCE(icp->state);
 
 		/* Set_MFRR */
 		new_state.mfrr = mfrr;
@@ -352,7 +352,7 @@ int kvmppc_rm_h_cppr(struct kvm_vcpu *vcpu, unsigned long cppr)
 	icp_rm_clr_vcpu_irq(icp->vcpu);
 
 	do {
-		old_state = new_state = ACCESS_ONCE(icp->state);
+		old_state = new_state = READ_ONCE(icp->state);
 
 		reject = 0;
 		new_state.cppr = cppr;

arch/powerpc/kvm/book3s_xics.c

@@ -327,7 +327,7 @@ static bool icp_try_to_deliver(struct kvmppc_icp *icp, u32 irq, u8 priority,
 		 icp->server_num);
 
 	do {
-		old_state = new_state = ACCESS_ONCE(icp->state);
+		old_state = new_state = READ_ONCE(icp->state);
 
 		*reject = 0;
 
@@ -512,7 +512,7 @@ static void icp_down_cppr(struct kvmppc_xics *xics, struct kvmppc_icp *icp,
 	 * in virtual mode.
 	 */
 	do {
-		old_state = new_state = ACCESS_ONCE(icp->state);
+		old_state = new_state = READ_ONCE(icp->state);
 
 		/* Down_CPPR */
 		new_state.cppr = new_cppr;
@@ -567,7 +567,7 @@ static noinline unsigned long kvmppc_h_xirr(struct kvm_vcpu *vcpu)
 	 * pending priority
 	 */
 	do {
-		old_state = new_state = ACCESS_ONCE(icp->state);
+		old_state = new_state = READ_ONCE(icp->state);
 
 		xirr = old_state.xisr | (((u32)old_state.cppr) << 24);
 		if (!old_state.xisr)
@@ -634,7 +634,7 @@ static noinline int kvmppc_h_ipi(struct kvm_vcpu *vcpu, unsigned long server,
 	 * whenever the MFRR is made less favored.
 	 */
 	do {
-		old_state = new_state = ACCESS_ONCE(icp->state);
+		old_state = new_state = READ_ONCE(icp->state);
 
 		/* Set_MFRR */
 		new_state.mfrr = mfrr;
@@ -679,7 +679,7 @@ static int kvmppc_h_ipoll(struct kvm_vcpu *vcpu, unsigned long server)
 		if (!icp)
 			return H_PARAMETER;
 	}
-	state = ACCESS_ONCE(icp->state);
+	state = READ_ONCE(icp->state);
 	kvmppc_set_gpr(vcpu, 4, ((u32)state.cppr << 24) | state.xisr);
 	kvmppc_set_gpr(vcpu, 5, state.mfrr);
 	return H_SUCCESS;
@@ -721,7 +721,7 @@ static noinline void kvmppc_h_cppr(struct kvm_vcpu *vcpu, unsigned long cppr)
 				      BOOK3S_INTERRUPT_EXTERNAL_LEVEL);
 
 	do {
-		old_state = new_state = ACCESS_ONCE(icp->state);
+		old_state = new_state = READ_ONCE(icp->state);
 
 		reject = 0;
 		new_state.cppr = cppr;
@@ -885,7 +885,7 @@ static int xics_debug_show(struct seq_file *m, void *private)
 		if (!icp)
 			continue;
 
-		state.raw = ACCESS_ONCE(icp->state.raw);
+		state.raw = READ_ONCE(icp->state.raw);
 		seq_printf(m, "cpu server %#lx XIRR:%#x PPRI:%#x CPPR:%#x MFRR:%#x OUT:%d NR:%d\n",
 			   icp->server_num, state.xisr,
 			   state.pending_pri, state.cppr, state.mfrr,
@@ -1082,7 +1082,7 @@ int kvmppc_xics_set_icp(struct kvm_vcpu *vcpu, u64 icpval)
 	 * the ICS states before the ICP states.
 	 */
 	do {
-		old_state = ACCESS_ONCE(icp->state);
+		old_state = READ_ONCE(icp->state);
 
 		if (new_state.mfrr <= old_state.mfrr) {
 			resend = false;