ide: preserve Host Protected Area by default (v2)

From the perspective of most users of recent systems, disabling Host
Protected Area (HPA) can break vendor RAID formats, GPT partitions and
risks corrupting firmware or overwriting vendor system recovery tools.

Unfortunately the original (kernels < 2.6.30) behavior (unconditionally
disabling HPA and using full disk capacity) was introduced at the time
when the main use of HPA was to make the drive look small enough for the
BIOS to allow the system to boot with large capacity drives.

Thus to allow the maximum compatibility with the existing setups (using
HPA and partitioned with HPA disabled) we automically disable HPA if
any partitions overlapping HPA are detected.  Additionally HPA can also
be disabled using the "nohpa" module parameter (i.e. "ide_core.nohpa=0.0"
to disable HPA on /dev/hda).

v2:
Fix ->resume HPA support.

While at it:
- remove stale "idebus=" entry from Documentation/kernel-parameters.txt

Cc: Robert Hancock <hancockrwd@gmail.com>
Cc: Frans Pop <elendil@planet.nl>
Cc: "Andries E. Brouwer" <Andries.Brouwer@cwi.nl>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
[patch description was based on input from Alan Cox and Frans Pop]
Emphatically-Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

5 files changed, 23 insertions, 6 deletions

diff --git a/Documentation/ide/ide.txt b/Documentation/ide/ide.txt
index 0c78f4b1d9d..e77bebfa7b0 100644
--- a/Documentation/ide/ide.txt
+++ b/Documentation/ide/ide.txt
@@ -216,6 +216,8 @@ Other kernel parameters for ide_core are:
 
 * "noflush=[interface_number.device_number]" to disable flush requests
 
+* "nohpa=[interface_number.device_number]" to disable Host Protected Area
+
 * "noprobe=[interface_number.device_number]" to skip probing
 
 * "nowerr=[interface_number.device_number]" to ignore the WRERR_STAT bit
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index a19f021f081..e58c91ca802 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -835,11 +835,8 @@ and is between 256 and 4096 characters. It is defined in the file
 
 	ide-core.nodma=	[HW] (E)IDE subsystem
 			Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
-			.vlb_clock .pci_clock .noflush .noprobe .nowerr .cdrom
-			.chs .ignore_cable are additional options
-			See Documentation/ide/ide.txt.
-
-	idebus=		[HW] (E)IDE subsystem - VLB/PCI bus speed
+			.vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
+			.cdrom .chs .ignore_cable are additional options
 			See Documentation/ide/ide.txt.
 
 	ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
diff --git a/drivers/ide/ide-disk.c b/drivers/ide/ide-disk.c
index 61a6d354622..3d92c9d54d4 100644
--- a/drivers/ide/ide-disk.c
+++ b/drivers/ide/ide-disk.c
@@ -350,6 +350,9 @@ static void idedisk_check_hpa(ide_drive_t *drive)
 			 capacity, sectors_to_MB(capacity),
 			 set_max, sectors_to_MB(set_max));
 
+	if ((drive->dev_flags & IDE_DFLAG_NOHPA) == 0)
+		return;
+
 	set_max = ide_disk_hpa_set_capacity(drive, set_max, lba48);
 	if (set_max)
 		printk(KERN_INFO "%s: Host Protected Area disabled.\n",
@@ -430,8 +433,11 @@ static u64 ide_disk_set_capacity(ide_drive_t *drive, u64 capacity)
 		goto out;
 
 	set = ide_disk_hpa_set_capacity(drive, set, lba48);
-	if (set)
+	if (set) {
+		/* needed for ->resume to disable HPA */
+		drive->dev_flags |= IDE_DFLAG_NOHPA;
 		return set;
+	}
 out:
 	return drive->capacity64;
 }
diff --git a/drivers/ide/ide.c b/drivers/ide/ide.c
index 92c9b90931e..16d056939f9 100644
--- a/drivers/ide/ide.c
+++ b/drivers/ide/ide.c
@@ -211,6 +211,11 @@ static unsigned int ide_noflush;
 module_param_call(noflush, ide_set_dev_param_mask, NULL, &ide_noflush, 0);
 MODULE_PARM_DESC(noflush, "disable flush requests for a device");
 
+static unsigned int ide_nohpa;
+
+module_param_call(nohpa, ide_set_dev_param_mask, NULL, &ide_nohpa, 0);
+MODULE_PARM_DESC(nohpa, "disable Host Protected Area for a device");
+
 static unsigned int ide_noprobe;
 
 module_param_call(noprobe, ide_set_dev_param_mask, NULL, &ide_noprobe, 0);
@@ -281,6 +286,11 @@ static void ide_dev_apply_params(ide_drive_t *drive, u8 unit)
 				 drive->name);
 		drive->dev_flags |= IDE_DFLAG_NOFLUSH;
 	}
+	if (ide_nohpa & (1 << i)) {
+		printk(KERN_INFO "ide: disabling Host Protected Area for %s\n",
+				 drive->name);
+		drive->dev_flags |= IDE_DFLAG_NOHPA;
+	}
 	if (ide_noprobe & (1 << i)) {
 		printk(KERN_INFO "ide: skipping probe for %s\n", drive->name);
 		drive->dev_flags |= IDE_DFLAG_NOPROBE;
diff --git a/include/linux/ide.h b/include/linux/ide.h
index e96ace12872..45dce3b4c88 100644
--- a/include/linux/ide.h
+++ b/include/linux/ide.h
@@ -475,6 +475,8 @@ enum {
 	IDE_DFLAG_NICE1			= (1 << 5),
 	/* device is physically present */
 	IDE_DFLAG_PRESENT		= (1 << 6),
+	/* disable Host Protected Area */
+	IDE_DFLAG_NOHPA			= (1 << 7),
 	/* id read from device (synthetic if not set) */
 	IDE_DFLAG_ID_READ		= (1 << 8),
 	IDE_DFLAG_NOPROBE		= (1 << 9),