diff --git a/arch/x86/kernel/apic/x2apic_uv_x.c b/arch/x86/kernel/apic/x2apic_uv_x.c
index f5a48e66e4f5..482855227964 100644
--- a/arch/x86/kernel/apic/x2apic_uv_x.c
+++ b/arch/x86/kernel/apic/x2apic_uv_x.c
@@ -199,7 +199,13 @@ static void __init uv_tsc_check_sync(void)
 	int mmr_shift;
 	char *state;
 
-	/* Different returns from different UV BIOS versions */
+	/* UV5 guarantees synced TSCs; do not zero TSC_ADJUST */
+	if (!is_uv(UV2|UV3|UV4)) {
+		mark_tsc_async_resets("UV5+");
+		return;
+	}
+
+	/* UV2,3,4, UV BIOS TSC sync state available */
 	mmr = uv_early_read_mmr(UVH_TSC_SYNC_MMR);
 	mmr_shift =
 		is_uv2_hub() ? UVH_TSC_SYNC_SHIFT_UV2K : UVH_TSC_SYNC_SHIFT;
@@ -1340,7 +1346,7 @@ static void __init decode_gam_params(unsigned long ptr)
 static void __init decode_gam_rng_tbl(unsigned long ptr)
 {
 	struct uv_gam_range_entry *gre = (struct uv_gam_range_entry *)ptr;
-	unsigned long lgre = 0;
+	unsigned long lgre = 0, gend = 0;
 	int index = 0;
 	int sock_min = 999999, pnode_min = 99999;
 	int sock_max = -1, pnode_max = -1;
@@ -1374,6 +1380,9 @@ static void __init decode_gam_rng_tbl(unsigned long ptr)
 			flag, size, suffix[order],
 			gre->type, gre->nasid, gre->sockid, gre->pnode);
 
+		if (gre->type == UV_GAM_RANGE_TYPE_HOLE)
+			gend = (unsigned long)gre->limit << UV_GAM_RANGE_SHFT;
+
 		/* update to next range start */
 		lgre = gre->limit;
 		if (sock_min > gre->sockid)
@@ -1391,7 +1400,8 @@ static void __init decode_gam_rng_tbl(unsigned long ptr)
 	_max_pnode	= pnode_max;
 	_gr_table_len	= index;
 
-	pr_info("UV: GRT: %d entries, sockets(min:%x,max:%x) pnodes(min:%x,max:%x)\n", index, _min_socket, _max_socket, _min_pnode, _max_pnode);
+	pr_info("UV: GRT: %d entries, sockets(min:%x,max:%x), pnodes(min:%x,max:%x), gap_end(%d)\n",
+	  index, _min_socket, _max_socket, _min_pnode, _max_pnode, fls64(gend));
 }
 
 /* Walk through UVsystab decoding the fields */
diff --git a/arch/x86/platform/uv/uv_nmi.c b/arch/x86/platform/uv/uv_nmi.c
index ea277fc08357..a60af0230e27 100644
--- a/arch/x86/platform/uv/uv_nmi.c
+++ b/arch/x86/platform/uv/uv_nmi.c
@@ -244,8 +244,10 @@ static inline bool uv_nmi_action_is(const char *action)
 /* Setup which NMI support is present in system */
 static void uv_nmi_setup_mmrs(void)
 {
+	bool new_nmi_method_only = false;
+
 	/* First determine arch specific MMRs to handshake with BIOS */
-	if (UVH_EVENT_OCCURRED0_EXTIO_INT0_MASK) {
+	if (UVH_EVENT_OCCURRED0_EXTIO_INT0_MASK) {	/* UV2,3,4 setup */
 		uvh_nmi_mmrx = UVH_EVENT_OCCURRED0;
 		uvh_nmi_mmrx_clear = UVH_EVENT_OCCURRED0_ALIAS;
 		uvh_nmi_mmrx_shift = UVH_EVENT_OCCURRED0_EXTIO_INT0_SHFT;
@@ -255,26 +257,25 @@ static void uv_nmi_setup_mmrs(void)
 		uvh_nmi_mmrx_req = UVH_BIOS_KERNEL_MMR_ALIAS_2;
 		uvh_nmi_mmrx_req_shift = 62;
 
-	} else if (UVH_EVENT_OCCURRED1_EXTIO_INT0_MASK) {
+	} else if (UVH_EVENT_OCCURRED1_EXTIO_INT0_MASK) { /* UV5+ setup */
 		uvh_nmi_mmrx = UVH_EVENT_OCCURRED1;
 		uvh_nmi_mmrx_clear = UVH_EVENT_OCCURRED1_ALIAS;
 		uvh_nmi_mmrx_shift = UVH_EVENT_OCCURRED1_EXTIO_INT0_SHFT;
 		uvh_nmi_mmrx_type = "OCRD1-EXTIO_INT0";
 
-		uvh_nmi_mmrx_supported = UVH_EXTIO_INT0_BROADCAST;
-		uvh_nmi_mmrx_req = UVH_BIOS_KERNEL_MMR_ALIAS_2;
-		uvh_nmi_mmrx_req_shift = 62;
+		new_nmi_method_only = true;		/* Newer nmi always valid on UV5+ */
+		uvh_nmi_mmrx_req = 0;			/* no request bit to clear */
 
 	} else {
-		pr_err("UV:%s:cannot find EVENT_OCCURRED*_EXTIO_INT0\n",
-			__func__);
+		pr_err("UV:%s:NMI support not available on this system\n", __func__);
 		return;
 	}
 
 	/* Then find out if new NMI is supported */
-	if (likely(uv_read_local_mmr(uvh_nmi_mmrx_supported))) {
-		uv_write_local_mmr(uvh_nmi_mmrx_req,
-					1UL << uvh_nmi_mmrx_req_shift);
+	if (new_nmi_method_only || uv_read_local_mmr(uvh_nmi_mmrx_supported)) {
+		if (uvh_nmi_mmrx_req)
+			uv_write_local_mmr(uvh_nmi_mmrx_req,
+						1UL << uvh_nmi_mmrx_req_shift);
 		nmi_mmr = uvh_nmi_mmrx;
 		nmi_mmr_clear = uvh_nmi_mmrx_clear;
 		nmi_mmr_pending = 1UL << uvh_nmi_mmrx_shift;