user/sven/linux.git/include/linux/hyperv.h, branch v5.15.199

Drivers: hv: vmbus: Add utility function for querying ring size

2025-07-10T13:57:36Z

[ Upstream commit e8c4bd6c6e6b7e7b416c42806981c2a81370001e ] Add a function to query for the preferred ring buffer size of VMBus device. This will allow the drivers (eg. UIO) to allocate the most optimized ring buffer size for devices. Signed-off-by: Saurabh Sengar Reviewed-by: Long Li Link: https://lore.kernel.org/r/1711788723-8593-2-git-send-email-ssengar@linux.microsoft.com Signed-off-by: Greg Kroah-Hartman Stable-dep-of: 0315fef2aff9 ("uio_hv_generic: Align ring size to system page") Signed-off-by: Sasha Levin

Drivers: hv: util: Avoid accessing a ringbuffer not initialized yet

2025-01-09T12:28:34Z

commit 07a756a49f4b4290b49ea46e089cbe6f79ff8d26 upstream. If the KVP (or VSS) daemon starts before the VMBus channel's ringbuffer is fully initialized, we can hit the panic below: hv_utils: Registering HyperV Utility Driver hv_vmbus: registering driver hv_utils ... BUG: kernel NULL pointer dereference, address: 0000000000000000 CPU: 44 UID: 0 PID: 2552 Comm: hv_kvp_daemon Tainted: G E 6.11.0-rc3+ #1 RIP: 0010:hv_pkt_iter_first+0x12/0xd0 Call Trace: ... vmbus_recvpacket hv_kvp_onchannelcallback vmbus_on_event tasklet_action_common tasklet_action handle_softirqs irq_exit_rcu sysvec_hyperv_stimer0 asm_sysvec_hyperv_stimer0 ... kvp_register_done hvt_op_read vfs_read ksys_read __x64_sys_read This can happen because the KVP/VSS channel callback can be invoked even before the channel is fully opened: 1) as soon as hv_kvp_init() -> hvutil_transport_init() creates /dev/vmbus/hv_kvp, the kvp daemon can open the device file immediately and register itself to the driver by writing a message KVP_OP_REGISTER1 to the file (which is handled by kvp_on_msg() ->kvp_handle_handshake()) and reading the file for the driver's response, which is handled by hvt_op_read(), which calls hvt->on_read(), i.e. kvp_register_done(). 2) the problem with kvp_register_done() is that it can cause the channel callback to be called even before the channel is fully opened, and when the channel callback is starting to run, util_probe()-> vmbus_open() may have not initialized the ringbuffer yet, so the callback can hit the panic of NULL pointer dereference. To reproduce the panic consistently, we can add a "ssleep(10)" for KVP in __vmbus_open(), just before the first hv_ringbuffer_init(), and then we unload and reload the driver hv_utils, and run the daemon manually within the 10 seconds. Fix the panic by reordering the steps in util_probe() so the char dev entry used by the KVP or VSS daemon is not created until after vmbus_open() has completed. This reordering prevents the race condition from happening. Reported-by: Dexuan Cui Fixes: e0fa3e5e7df6 ("Drivers: hv: utils: fix a race on userspace daemons registration") Cc: stable@vger.kernel.org Signed-off-by: Michael Kelley Acked-by: Wei Liu Link: https://lore.kernel.org/r/20241106154247.2271-3-mhklinux@outlook.com Signed-off-by: Wei Liu Message-ID: <20241106154247.2271-3-mhklinux@outlook.com> Signed-off-by: Greg Kroah-Hartman

Drivers: hv: vmbus: Calculate ring buffer size for more efficient use of memory

2024-04-10T14:18:44Z

commit b8209544296edbd1af186e2ea9c648642c37b18c upstream. The VMBUS_RING_SIZE macro adds space for a ring buffer header to the requested ring buffer size. The header size is always 1 page, and so its size varies based on the PAGE_SIZE for which the kernel is built. If the requested ring buffer size is a large power-of-2 size and the header size is small, the resulting size is inefficient in its use of memory. For example, a 512 Kbyte ring buffer with a 4 Kbyte page size results in a 516 Kbyte allocation, which is rounded to up 1 Mbyte by the memory allocator, and wastes 508 Kbytes of memory. In such situations, the exact size of the ring buffer isn't that important, and it's OK to allocate the 4 Kbyte header at the beginning of the 512 Kbytes, leaving the ring buffer itself with just 508 Kbytes. The memory allocation can be 512 Kbytes instead of 1 Mbyte and nothing is wasted. Update VMBUS_RING_SIZE to implement this approach for "large" ring buffer sizes. "Large" is somewhat arbitrarily defined as 8 times the size of the ring buffer header (which is of size PAGE_SIZE). For example, for 4 Kbyte PAGE_SIZE, ring buffers of 32 Kbytes and larger use the first 4 Kbytes as the ring buffer header. For 64 Kbyte PAGE_SIZE, ring buffers of 512 Kbytes and larger use the first 64 Kbytes as the ring buffer header. In both cases, smaller sizes add space for the header so the ring size isn't reduced too much by using part of the space for the header. For example, with a 64 Kbyte page size, we don't want a 128 Kbyte ring buffer to be reduced to 64 Kbytes by allocating half of the space for the header. In such a case, the memory allocation is less efficient, but it's the best that can be done. While the new algorithm slightly changes the amount of space allocated for ring buffers by drivers that use VMBUS_RING_SIZE, the devices aren't known to be sensitive to small changes in ring buffer size, so there shouldn't be any effect. Fixes: c1135c7fd0e9 ("Drivers: hv: vmbus: Introduce types of GPADL") Fixes: 6941f67ad37d ("hv_netvsc: Calculate correct ring size when PAGE_SIZE is not 4 Kbytes") Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218502 Cc: stable@vger.kernel.org Signed-off-by: Michael Kelley Reviewed-by: Saurabh Sengar Reviewed-by: Dexuan Cui Tested-by: Souradeep Chakrabarti Link: https://lore.kernel.org/r/20240229004533.313662-1-mhklinux@outlook.com Signed-off-by: Wei Liu Message-ID: <20240229004533.313662-1-mhklinux@outlook.com> Signed-off-by: Greg Kroah-Hartman

video: hyperv_fb: Avoid taking busy spinlock on panic path

2022-12-31T12:14:39Z

[ Upstream commit 1d044ca035dc22df0d3b39e56f2881071d9118bd ] The Hyper-V framebuffer code registers a panic notifier in order to try updating its fbdev if the kernel crashed. The notifier callback is straightforward, but it calls the vmbus_sendpacket() routine eventually, and such function takes a spinlock for the ring buffer operations. Panic path runs in atomic context, with local interrupts and preemption disabled, and all secondary CPUs shutdown. That said, taking a spinlock might cause a lockup if a secondary CPU was disabled with such lock taken. Fix it here by checking if the ring buffer spinlock is busy on Hyper-V framebuffer panic notifier; if so, bail-out avoiding the potential lockup scenario. Cc: Andrea Parri (Microsoft) Cc: Dexuan Cui Cc: Haiyang Zhang Cc: "K. Y. Srinivasan" Cc: Michael Kelley Cc: Stephen Hemminger Cc: Tianyu Lan Cc: Wei Liu Tested-by: Fabio A M Martins Signed-off-by: Guilherme G. Piccoli Reviewed-by: Michael Kelley Link: https://lore.kernel.org/r/20220819221731.480795-10-gpiccoli@igalia.com Signed-off-by: Wei Liu Signed-off-by: Sasha Levin

hv: hyperv.h: Remove unused inline functions

2021-07-22T10:14:25Z

There are some unused inline functions in hyper.h. Remove those unused functions. Signed-off-by: Sonia Sharma Reviewed-by: Michael Kelley Link: https://lore.kernel.org/r/1626903663-23615-1-git-send-email-sosha@linux.microsoft.com Signed-off-by: Wei Liu

scsi: storvsc: Use blk_mq_unique_tag() to generate requestIDs

2021-05-14T17:39:32Z

Use blk_mq_unique_tag() to generate requestIDs for StorVSC, avoiding all issues with allocating enough entries in the VMbus requestor. Suggested-by: Michael Kelley Signed-off-by: Andrea Parri (Microsoft) Reviewed-by: Michael Kelley Acked-by: Martin K. Petersen Link: https://lore.kernel.org/r/20210510210841.370472-1-parri.andrea@gmail.com Signed-off-by: Wei Liu

Drivers: hv: vmbus: Copy packets sent by Hyper-V out of the ring buffer

2021-05-14T17:37:46Z

Pointers to ring-buffer packets sent by Hyper-V are used within the guest VM. Hyper-V can send packets with erroneous values or modify packet fields after they are processed by the guest. To defend against these scenarios, return a copy of the incoming VMBus packet after validating its length and offset fields in hv_pkt_iter_first(). In this way, the packet can no longer be modified by the host. Signed-off-by: Andres Beltran Co-developed-by: Andrea Parri (Microsoft) Signed-off-by: Andrea Parri (Microsoft) Reviewed-by: Michael Kelley Link: https://lore.kernel.org/r/20210408161439.341988-1-parri.andrea@gmail.com Signed-off-by: Wei Liu

Merge tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi

2021-04-29T00:22:10Z

Pull SCSI updates from James Bottomley: "This consists of the usual driver updates (ufs, target, tcmu, smartpqi, lpfc, zfcp, qla2xxx, mpt3sas, pm80xx). The major core change is using a sbitmap instead of an atomic for queue tracking" * tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (412 commits) scsi: target: tcm_fc: Fix a kernel-doc header scsi: target: Shorten ALUA error messages scsi: target: Fix two format specifiers scsi: target: Compare explicitly with SAM_STAT_GOOD scsi: sd: Introduce a new local variable in sd_check_events() scsi: dc395x: Open-code status_byte(u8) calls scsi: 53c700: Open-code status_byte(u8) calls scsi: smartpqi: Remove unused functions scsi: qla4xxx: Remove an unused function scsi: myrs: Remove unused functions scsi: myrb: Remove unused functions scsi: mpt3sas: Fix two kernel-doc headers scsi: fcoe: Suppress a compiler warning scsi: libfc: Fix a format specifier scsi: aacraid: Remove an unused function scsi: core: Introduce enum scsi_disposition scsi: core: Modify the scsi_send_eh_cmnd() return value for the SDEV_BLOCK case scsi: core: Rename scsi_softirq_done() into scsi_complete() scsi: core: Remove an incorrect comment scsi: core: Make the scsi_alloc_sgtables() documentation more accurate ...

Drivers: hv: vmbus: Drivers: hv: vmbus: Introduce CHANNELMSG_MODIFYCHANNEL_RESPONSE

2021-04-18T13:03:11Z

Introduce the CHANNELMSG_MODIFYCHANNEL_RESPONSE message type, and code to receive and process such a message. Signed-off-by: Andrea Parri (Microsoft) Reviewed-by: Michael Kelley Link: https://lore.kernel.org/r/20210416143449.16185-3-parri.andrea@gmail.com Signed-off-by: Wei Liu

Drivers: hv: vmbus: Introduce and negotiate VMBus protocol version 5.3

2021-04-18T13:03:11Z

Hyper-V has added VMBus protocol version 5.3. Allow Linux guests to negotiate the new version on version of Hyper-V that support it. Signed-off-by: Andrea Parri (Microsoft) Reviewed-by: Michael Kelley Link: https://lore.kernel.org/r/20210416143449.16185-2-parri.andrea@gmail.com Signed-off-by: Wei Liu