x86/platform/uv: Update NMI Handler for UV5

Update NMI handler for UV5 hardware. A platform register changed, and
UV5 only uses one of the two NMI methods used on previous hardware.
Signed-off-by: Mike Travis <mike.travis@hpe.com>
Signed-off-by: Steve Wahl <steve.wahl@hpe.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Dimitri Sivanich <dimitri.sivanich@hpe.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20220406195149.228164-2-steve.wahl@hpe.com

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;