From e8aabc64d7f5c8702e420c6fa478368f60718ae4 Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Sun, 3 Apr 2016 15:22:08 +0300 Subject: [PATCH 1/5] qemu_fw_cfg: don't leak kobj on init error If platform_driver_register fails, we should cleanup fw_cfg_top_ko before exiting. Signed-off-by: Michael S. Tsirkin Acked-by: Gabriel Somlo --- drivers/firmware/qemu_fw_cfg.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/firmware/qemu_fw_cfg.c b/drivers/firmware/qemu_fw_cfg.c index fedbff55a7f3..e4c471413d46 100644 --- a/drivers/firmware/qemu_fw_cfg.c +++ b/drivers/firmware/qemu_fw_cfg.c @@ -727,12 +727,18 @@ 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) From 05dbcb430795b2e1fb1d5c757f8619d3dbed0a1c Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Sun, 3 Apr 2016 15:23:37 +0300 Subject: [PATCH 2/5] virtio: virtio 1.0 cs04 spec compliance for reset The spec says: after writing 0 to device_status, the driver MUST wait for a read of device_status to return 0 before reinitializing the device. Cc: stable@vger.kernel.org Signed-off-by: Michael S. Tsirkin Acked-by: Jason Wang --- drivers/virtio/virtio_pci_modern.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) 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 #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); } From def7ac806a9ac035abf0e7573ccc8bbfd38e163c Mon Sep 17 00:00:00 2001 From: Gabriel Somlo Date: Tue, 8 Mar 2016 13:30:50 -0500 Subject: [PATCH 3/5] firmware: qemu_fw_cfg.c: hold ACPI global lock during device access Allowing for the future possibility of implementing AML-based (i.e., firmware-triggered) access to the QEMU fw_cfg device, acquire the global ACPI lock when accessing the device on behalf of the guest-side sysfs driver, to prevent any potential race conditions. Suggested-by: Michael S. Tsirkin Signed-off-by: Gabriel Somlo Signed-off-by: Michael S. Tsirkin --- drivers/firmware/qemu_fw_cfg.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/drivers/firmware/qemu_fw_cfg.c b/drivers/firmware/qemu_fw_cfg.c index e4c471413d46..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 */ From eeca9a671aaa6a77eaed725e842d53c5ce51940b Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Tue, 5 Apr 2016 11:26:44 +0300 Subject: [PATCH 4/5] MAINTAINERS: add entry for QEMU Gabriel merged support for QEMU FW CFG interface, but there's apparently no official maintainer. It's also possible that this will grow more interfaces in future. I'll happily co-maintain it and handle pull requests together with the rest of the PV stuff I maintain. Cc: Greg Kroah-Hartman Cc: Gabriel Somlo Signed-off-by: Michael S. Tsirkin Acked-by: Gabriel Somlo --- MAINTAINERS | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/MAINTAINERS b/MAINTAINERS index 1c32f8a3d6c4..17911286cba9 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -9140,6 +9140,13 @@ 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 +M: "Michael S. Tsirkin" +L: qemu-devel@nongnu.org +S: Maintained +F: drivers/firmware/qemu_fw_cfg.c + RADOS BLOCK DEVICE (RBD) M: Ilya Dryomov M: Sage Weil From c00bbcf8628969e103d4a7b351a53746f1025576 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Tue, 29 Mar 2016 16:43:45 +0100 Subject: [PATCH 5/5] virtio: add VIRTIO_CONFIG_S_NEEDS_RESET device status bit The VIRTIO 1.0 specification added the DEVICE_NEEDS_RESET device status bit in "VIRTIO-98: Add DEVICE_NEEDS_RESET". This patch defines the device status bit in the uapi header file so that both the kernel and userspace applications can use it. The bit is currently unused by the virtio guest drivers and vhost. According to the spec "a good implementation will try to recover by issuing a reset". This is not attempted here because it requires auditing the virtio drivers to ensure there are no resource leaks or crashes if the device needs to be reset mid-operation. See "2.1 Device Status Field" in the VIRTIO 1.0 specification for details. Signed-off-by: Stefan Hajnoczi Signed-off-by: Michael S. Tsirkin --- include/uapi/linux/virtio_config.h | 2 ++ 1 file changed, 2 insertions(+) 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