Revert "UBUNTU: SAUCE: rfi-flush: Rework powernv logic to be more cautious"

This reverts commit 88424261.

CVE-2017-5754

BugLink: http://bugs.launchpad.net/bugs/1756121

The functionality of this commit will be provided by the following
upstream patch series:
  * powerpc/64s: Allow control of RFI flush via debugfs
  * powerpc/64s: Wire up cpu_show_meltdown()
  * powerpc/powernv: Check device-tree for RFI flush settings
  * powerpc/pseries: Query hypervisor for RFI flush settings
  * powerpc/64s: Support disabling RFI flush with no_rfi_flush and nopti
  * powerpc/64s: Add support for RFI flush of L1-D cache
  * powerpc/64s: Convert slb_miss_common to use RFI_TO_USER/KERNEL
  * powerpc/64: Convert the syscall exit path to use RFI_TO_USER/KERNEL
  * powerpc/64: Convert fast_exception_return to use RFI_TO_USER/KERNEL
  * powerpc/64s: Simple RFI macro conversions
  * powerpc/64: Add macros for annotating the destination of rfid/hrfid
  * powerpc/pseries: Add H_GET_CPU_CHARACTERISTICS flags & wrapper
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

arch/powerpc/platforms/powernv/setup.c

@@ -43,17 +43,20 @@ static void pnv_setup_rfi_flush(void)
 {
 	struct device_node *np, *fw_features;
 	enum l1d_flush_type type;
-	int enable;
+	bool enable;
 
 	/* Default to fallback in case fw-features are not available */
 	type = L1D_FLUSH_FALLBACK;
-	enable = 1;
+	enable = true;
 
 	np = of_find_node_by_name(NULL, "ibm,opal");
 	fw_features = of_get_child_by_name(np, "fw-features");
 	of_node_put(np);
 
 	if (fw_features) {
+		/* Default to no flush, unless firmware says otherwise */
+		type = L1D_FLUSH_NONE;
+
 		np = of_get_child_by_name(fw_features, "inst-l1d-flush-trig2");
 		if (np && of_property_read_bool(np, "enabled"))
 			type = L1D_FLUSH_MTTRIG;
@@ -66,23 +69,23 @@ static void pnv_setup_rfi_flush(void)
 
 		of_node_put(np);
 
-		/* Enable unless firmware says NOT to */
-		enable = 2;
+		/* Don't enable unless firmware says so */
+		enable = false;
 		np = of_get_child_by_name(fw_features, "needs-l1d-flush-msr-hv-1-to-0");
-		if (np && of_property_read_bool(np, "disabled"))
-			enable--;
+		if (np && of_property_read_bool(np, "enabled"))
+			enable = true;
 
 		of_node_put(np);
 
 		np = of_get_child_by_name(fw_features, "needs-l1d-flush-msr-pr-0-to-1");
-		if (np && of_property_read_bool(np, "disabled"))
-			enable--;
+		if (np && of_property_read_bool(np, "enabled"))
+			enable = true;
 
 		of_node_put(np);
 		of_node_put(fw_features);
 	}
 
-	setup_rfi_flush(type, enable > 0);
+	setup_rfi_flush(type, enable);
 }
 
 static void __init pnv_setup_arch(void)