---

yaml
---
r: 305869
b: refs/heads/master
c: cd00608
h: refs/heads/master
i:
  305867: ab15682
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: db63a4c8115a0bb904496e1cdd3e7488e68b0d06
+refs/heads/master: cd006086fa5d91414d8ff9ff2b78fbb593878e3c

trunk/drivers/ata/ata_piix.c

@@ -1554,6 +1554,39 @@ static bool piix_broken_system_poweroff(struct pci_dev *pdev)
 	return false;
 }
 
+static int prefer_ms_hyperv = 1;
+module_param(prefer_ms_hyperv, int, 0);
+
+static void piix_ignore_devices_quirk(struct ata_host *host)
+{
+#if IS_ENABLED(CONFIG_HYPERV_STORAGE)
+	static const struct dmi_system_id ignore_hyperv[] = {
+		{
+			/* On Hyper-V hypervisors the disks are exposed on
+			 * both the emulated SATA controller and on the
+			 * paravirtualised drivers.  The CD/DVD devices
+			 * are only exposed on the emulated controller.
+			 * Request we ignore ATA devices on this host.
+			 */
+			.ident = "Hyper-V Virtual Machine",
+			.matches = {
+				DMI_MATCH(DMI_SYS_VENDOR,
+						"Microsoft Corporation"),
+				DMI_MATCH(DMI_PRODUCT_NAME, "Virtual Machine"),
+			},
+		},
+		{ }	/* terminate list */
+	};
+	const struct dmi_system_id *dmi = dmi_first_match(ignore_hyperv);
+
+	if (dmi && prefer_ms_hyperv) {
+		host->flags |= ATA_HOST_IGNORE_ATA;
+		dev_info(host->dev, "%s detected, ATA device ignore set\n",
+			dmi->ident);
+	}
+#endif
+}
+
 /**
  *	piix_init_one - Register PIIX ATA PCI device with kernel services
  *	@pdev: PCI device to register
@@ -1669,6 +1702,9 @@ static int __devinit piix_init_one(struct pci_dev *pdev,
 	}
 	host->flags |= ATA_HOST_PARALLEL_SCAN;
 
+	/* Allow hosts to specify device types to ignore when scanning. */
+	piix_ignore_devices_quirk(host);
+
 	pci_set_master(pdev);
 	return ata_pci_sff_activate_host(host, ata_bmdma_interrupt, sht);
 }