Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost

Pull virtio/qemu fixes from Michael S Tsirkin:
 "A couple of fixes for virtio and for the new QEMU fw cfg driver"

* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
  virtio: add VIRTIO_CONFIG_S_NEEDS_RESET device status bit
  MAINTAINERS: add entry for QEMU
  firmware: qemu_fw_cfg.c: hold ACPI global lock during device access
  virtio: virtio 1.0 cs04 spec compliance for reset
  qemu_fw_cfg: don't leak kobj on init error

4 files changed, 40 insertions, 4 deletions

diff --git a/MAINTAINERS b/MAINTAINERS
index 40eb1dbe2ae5..d8c901bbec89 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9142,6 +9142,13 @@ T:	git git://github.com/KrasnikovEugene/wcn36xx.git
 S:      Supported
 F:      drivers/net/wireless/ath/wcn36xx/
 
+QEMU MACHINE EMULATOR AND VIRTUALIZER SUPPORT
+M:      Gabriel Somlo <somlo@cmu.edu>
+M:      "Michael S. Tsirkin" <mst@redhat.com>
+L:      qemu-devel@nongnu.org
+S:      Maintained
+F:      drivers/firmware/qemu_fw_cfg.c
+
 RADOS BLOCK DEVICE (RBD)
 M:      Ilya Dryomov <idryomov@gmail.com>
 M:      Sage Weil <sage@redhat.com>
diff --git a/drivers/firmware/qemu_fw_cfg.c b/drivers/firmware/qemu_fw_cfg.c
index fedbff55a7f3..815c4a5cae54 100644
--- a/drivers/firmware/qemu_fw_cfg.c
+++ b/drivers/firmware/qemu_fw_cfg.c
@@ -77,12 +77,28 @@ static inline u16 fw_cfg_sel_endianness(u16 key)
 static inline void fw_cfg_read_blob(u16 key,
                                     void *buf, loff_t pos, size_t count)
 {
+        u32 glk;
+        acpi_status status;
+
+        /* If we have ACPI, ensure mutual exclusion against any potential
+         * device access by the firmware, e.g. via AML methods:
+         */
+        status = acpi_acquire_global_lock(ACPI_WAIT_FOREVER, &glk);
+        if (ACPI_FAILURE(status) && status != AE_NOT_CONFIGURED) {
+                /* Should never get here */
+                WARN(1, "fw_cfg_read_blob: Failed to lock ACPI!\n");
+                memset(buf, 0, count);
+                return;
+        }
+
         mutex_lock(&fw_cfg_dev_lock);
         iowrite16(fw_cfg_sel_endianness(key), fw_cfg_reg_ctrl);
         while (pos-- > 0)
                 ioread8(fw_cfg_reg_data);
         ioread8_rep(fw_cfg_reg_data, buf, count);
         mutex_unlock(&fw_cfg_dev_lock);
+
+        acpi_release_global_lock(glk);
 }
 
 /* clean up fw_cfg device i/o */
@@ -727,12 +743,18 @@ device_param_cb(mmio, &fw_cfg_cmdline_param_ops, NULL, S_IRUSR);
 
 static int __init fw_cfg_sysfs_init(void)
 {
+        int ret;
+
         /* create /sys/firmware/qemu_fw_cfg/ top level directory */
         fw_cfg_top_ko = kobject_create_and_add("qemu_fw_cfg", firmware_kobj);
         if (!fw_cfg_top_ko)
                 return -ENOMEM;
 
-        return platform_driver_register(&fw_cfg_sysfs_driver);
+        ret = platform_driver_register(&fw_cfg_sysfs_driver);
+        if (ret)
+                fw_cfg_kobj_cleanup(fw_cfg_top_ko);
+
+        return ret;
 }
 
 static void __exit fw_cfg_sysfs_exit(void)
diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c
index f6f28cc7eb45..e76bd91a29da 100644
--- a/drivers/virtio/virtio_pci_modern.c
+++ b/drivers/virtio/virtio_pci_modern.c
@@ -17,6 +17,7 @@
  *
  */
 
+#include <linux/delay.h>
 #define VIRTIO_PCI_NO_LEGACY
 #include "virtio_pci_common.h"
 
@@ -271,9 +272,13 @@ static void vp_reset(struct virtio_device *vdev)
         struct virtio_pci_device *vp_dev = to_vp_device(vdev);
         /* 0 status means a reset. */
         vp_iowrite8(0, &vp_dev->common->device_status);
-        /* Flush out the status write, and flush in device writes,
-         * including MSI-X interrupts, if any. */
-        vp_ioread8(&vp_dev->common->device_status);
+        /* After writing 0 to device_status, the driver MUST wait for a read of
+         * device_status to return 0 before reinitializing the device.
+         * This will flush out the status write, and flush in device writes,
+         * including MSI-X interrupts, if any.
+         */
+        while (vp_ioread8(&vp_dev->common->device_status))
+                msleep(1);
         /* Flush pending VQ/configuration callbacks. */
         vp_synchronize_vectors(vdev);
 }
diff --git a/include/uapi/linux/virtio_config.h b/include/uapi/linux/virtio_config.h
index c18264df9504..4cb65bbfa654 100644
--- a/include/uapi/linux/virtio_config.h
+++ b/include/uapi/linux/virtio_config.h
@@ -40,6 +40,8 @@
 #define VIRTIO_CONFIG_S_DRIVER_OK       4
 /* Driver has finished configuring features */
 #define VIRTIO_CONFIG_S_FEATURES_OK     8
+/* Device entered invalid state, driver must reset it */
+#define VIRTIO_CONFIG_S_NEEDS_RESET     0x40
 /* We've given up on this device. */
 #define VIRTIO_CONFIG_S_FAILED          0x80