ata_piix: reenable MS Virtual PC guests

An earlier commit cd006086fa5d91414d8ff9ff2b78fbb593878e3c ("ata_piix:
defer disks to the Hyper-V drivers by default") broke MS Virtual PC
guests. Hyper-V guests and Virtual PC guests have nearly identical DMI
info. As a result the driver does currently ignore the emulated hardware
in Virtual PC guests and defers the handling to hv_blkvsc. Since Virtual
PC does not offer paravirtualized drivers no disks will be found in the
guest.

One difference in the DMI info is the product version. This patch adds a
match for MS Virtual PC 2007 and "unignores" the emulated hardware.

This was reported for openSuSE 12.1 in bugzilla:
https://bugzilla.novell.com/show_bug.cgi?id=737532

Here is a detailed list of DMI info from example guests:

hwinfo --bios:

virtual pc guest:

  System Info: #1
    Manufacturer: "Microsoft Corporation"
    Product: "Virtual Machine"
    Version: "VS2005R2"
    Serial: "3178-9905-1533-4840-9282-0569-59"
    UUID: undefined, but settable
    Wake-up: 0x06 (Power Switch)
  Board Info: #2
    Manufacturer: "Microsoft Corporation"
    Product: "Virtual Machine"
    Version: "5.0"
    Serial: "3178-9905-1533-4840-9282-0569-59"
  Chassis Info: #3
    Manufacturer: "Microsoft Corporation"
    Version: "5.0"
    Serial: "3178-9905-1533-4840-9282-0569-59"
    Asset Tag: "7188-3705-6309-9738-9645-0364-00"
    Type: 0x03 (Desktop)
    Bootup State: 0x03 (Safe)
    Power Supply State: 0x03 (Safe)
    Thermal State: 0x01 (Other)
    Security Status: 0x01 (Other)

win2k8 guest:

  System Info: #1
    Manufacturer: "Microsoft Corporation"
    Product: "Virtual Machine"
    Version: "7.0"
    Serial: "9106-3420-9819-5495-1514-2075-48"
    UUID: undefined, but settable
    Wake-up: 0x06 (Power Switch)
  Board Info: #2
    Manufacturer: "Microsoft Corporation"
    Product: "Virtual Machine"
    Version: "7.0"
    Serial: "9106-3420-9819-5495-1514-2075-48"
  Chassis Info: #3
    Manufacturer: "Microsoft Corporation"
    Version: "7.0"
    Serial: "9106-3420-9819-5495-1514-2075-48"
    Asset Tag: "7076-9522-6699-1042-9501-1785-77"
    Type: 0x03 (Desktop)
    Bootup State: 0x03 (Safe)
    Power Supply State: 0x03 (Safe)
    Thermal State: 0x01 (Other)
    Security Status: 0x01 (Other)

win2k12 guest:

  System Info: #1
    Manufacturer: "Microsoft Corporation"
    Product: "Virtual Machine"
    Version: "7.0"
    Serial: "8179-1954-0187-0085-3868-2270-14"
    UUID: undefined, but settable
    Wake-up: 0x06 (Power Switch)
  Board Info: #2
    Manufacturer: "Microsoft Corporation"
    Product: "Virtual Machine"
    Version: "7.0"
    Serial: "8179-1954-0187-0085-3868-2270-14"
  Chassis Info: #3
    Manufacturer: "Microsoft Corporation"
    Version: "7.0"
    Serial: "8179-1954-0187-0085-3868-2270-14"
    Asset Tag: "8374-0485-4557-6331-0620-5845-25"
    Type: 0x03 (Desktop)
    Bootup State: 0x03 (Safe)
    Power Supply State: 0x03 (Safe)
    Thermal State: 0x01 (Other)
    Security Status: 0x01 (Other)

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 22 insertions, 3 deletions

diff --git a/drivers/ata/ata_piix.c b/drivers/ata/ata_piix.c
index ef773e12af79..bec35f491cb9 100644
--- a/drivers/ata/ata_piix.c
+++ b/drivers/ata/ata_piix.c
@@ -1585,12 +1585,31 @@ static void piix_ignore_devices_quirk(struct ata_host *host)
                 },
                 { }     /* terminate list */
         };
-        const struct dmi_system_id *dmi = dmi_first_match(ignore_hyperv);
+        static const struct dmi_system_id allow_virtual_pc[] = {
+                {
+                        /* In MS Virtual PC guests the DMI ident is nearly
+                         * identical to a Hyper-V guest. One difference is the
+                         * product version which is used here to identify
+                         * a Virtual PC guest. This entry allows ata_piix to
+                         * drive the emulated hardware.
+                         */
+                        .ident = "MS Virtual PC 2007",
+                        .matches = {
+                                DMI_MATCH(DMI_SYS_VENDOR,
+                                                "Microsoft Corporation"),
+                                DMI_MATCH(DMI_PRODUCT_NAME, "Virtual Machine"),
+                                DMI_MATCH(DMI_PRODUCT_VERSION, "VS2005R2"),
+                        },
+                },
+                { }     /* terminate list */
+        };
+        const struct dmi_system_id *ignore = dmi_first_match(ignore_hyperv);
+        const struct dmi_system_id *allow = dmi_first_match(allow_virtual_pc);
 
-        if (dmi && prefer_ms_hyperv) {
+        if (ignore && !allow && prefer_ms_hyperv) {
                 host->flags |= ATA_HOST_IGNORE_ATA;
                 dev_info(host->dev, "%s detected, ATA device ignore set\n",
-                        dmi->ident);
+                        ignore->ident);
         }
 #endif
 }