KVM: PPC: Book3S HV: Don't access XIVE PIPR register using byte accesses

The XIVE interrupt controller on POWER9 machines doesn't support byte
accesses to any register in the thread management area other than the
CPPR (current processor priority register).  In particular, when
reading the PIPR (pending interrupt priority register), we need to
do a 32-bit or 64-bit load.

Cc: stable@vger.kernel.org # v4.13
Fixes: 2c4fb78 ("KVM: PPC: Book3S HV: Workaround POWER9 DD1.0 bug causing IPB bit loss")
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

arch/powerpc/kvm/book3s_hv_rm_xive.c

@@ -38,7 +38,6 @@ static inline void __iomem *get_tima_phys(void)
 #define __x_tima		get_tima_phys()
 #define __x_eoi_page(xd)	((void __iomem *)((xd)->eoi_page))
 #define __x_trig_page(xd)	((void __iomem *)((xd)->trig_page))
-#define __x_readb	__raw_rm_readb
 #define __x_writeb	__raw_rm_writeb
 #define __x_readw	__raw_rm_readw
 #define __x_readq	__raw_rm_readq

arch/powerpc/kvm/book3s_xive.c

@@ -48,7 +48,6 @@
 #define __x_tima		xive_tima
 #define __x_eoi_page(xd)	((void __iomem *)((xd)->eoi_mmio))
 #define __x_trig_page(xd)	((void __iomem *)((xd)->trig_mmio))
-#define __x_readb	__raw_readb
 #define __x_writeb	__raw_writeb
 #define __x_readw	__raw_readw
 #define __x_readq	__raw_readq

arch/powerpc/kvm/book3s_xive_template.c

@@ -28,7 +28,8 @@ static void GLUE(X_PFX,ack_pending)(struct kvmppc_xive_vcpu *xc)
 	 * bit.
 	 */
 	if (cpu_has_feature(CPU_FTR_POWER9_DD1)) {
-		u8 pipr = __x_readb(__x_tima + TM_QW1_OS + TM_PIPR);
+		__be64 qw1 = __x_readq(__x_tima + TM_QW1_OS);
+		u8 pipr = be64_to_cpu(qw1) & 0xff;
 		if (pipr >= xc->hw_cppr)
 			return;
 	}
@@ -336,7 +337,6 @@ X_STATIC unsigned long GLUE(X_PFX,h_ipoll)(struct kvm_vcpu *vcpu, unsigned long
 	struct kvmppc_xive_vcpu *xc = vcpu->arch.xive_vcpu;
 	u8 pending = xc->pending;
 	u32 hirq;
-	u8 pipr;
 
 	pr_devel("H_IPOLL(server=%ld)\n", server);
 
@@ -353,7 +353,8 @@ X_STATIC unsigned long GLUE(X_PFX,h_ipoll)(struct kvm_vcpu *vcpu, unsigned long
 		pending = 0xff;
 	} else {
 		/* Grab pending interrupt if any */
-		pipr = __x_readb(__x_tima + TM_QW1_OS + TM_PIPR);
+		__be64 qw1 = __x_readq(__x_tima + TM_QW1_OS);
+		u8 pipr = be64_to_cpu(qw1) & 0xff;
 		if (pipr < 8)
 			pending |= 1 << pipr;
 	}