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2021-11-28hv: utils: add PTP_1588_CLOCK to Kconfig to fix buildRandy Dunlap
The hyperv utilities use PTP clock interfaces and should depend a a kconfig symbol such that they will be built as a loadable module or builtin so that linker errors do not happen. Prevents these build errors: ld: drivers/hv/hv_util.o: in function `hv_timesync_deinit': hv_util.c:(.text+0x37d): undefined reference to `ptp_clock_unregister' ld: drivers/hv/hv_util.o: in function `hv_timesync_init': hv_util.c:(.text+0x738): undefined reference to `ptp_clock_register' Fixes: 3716a49a81ba ("hv_utils: implement Hyper-V PTP source") Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Reported-by: kernel test robot <lkp@intel.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: "K. Y. Srinivasan" <kys@microsoft.com> Cc: Haiyang Zhang <haiyangz@microsoft.com> Cc: Stephen Hemminger <sthemmin@microsoft.com> Cc: Wei Liu <wei.liu@kernel.org> Cc: Dexuan Cui <decui@microsoft.com> Cc: linux-hyperv@vger.kernel.org Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Michael Kelley <mikelley@microsoft.com> Link: https://lore.kernel.org/r/20211126023316.25184-1-rdunlap@infradead.org Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-11-15Drivers: hv: balloon: Use VMBUS_RING_SIZE() wrapper for dm_ring_sizeBoqun Feng
Baihua reported an error when boot an ARM64 guest with PAGE_SIZE=64k and BALLOON is enabled: hv_vmbus: registering driver hv_balloon hv_vmbus: probe failed for device 1eccfd72-4b41-45ef-b73a-4a6e44c12924 (-22) The cause of this is that the ringbuffer size for hv_balloon is not adjusted with VMBUS_RING_SIZE(), which makes the size not large enough for ringbuffers on guest with PAGE_SIZE=64k. Therefore use VMBUS_RING_SIZE() to calculate the ringbuffer size. Note that the old size (20 * 1024) counts a 4k header in the total size, while VMBUS_RING_SIZE() expects the parameter as the payload size, so use 16 * 1024. Cc: <stable@vger.kernel.org> # 5.15.x Reported-by: Baihua Lu <baihua.lu@microsoft.com> Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Tested-by: Vitaly Kuznetsov <vkuznets@redhat.com> Link: https://lore.kernel.org/r/20211101150026.736124-1-boqun.feng@gmail.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-11-02Merge tag 'hyperv-next-signed-20211102' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux Pull hyperv updates from Wei Liu: - Initial patch set for Hyper-V isolation VM support (Tianyu Lan) - Fix a warning on preemption (Vitaly Kuznetsov) - A bunch of misc cleanup patches * tag 'hyperv-next-signed-20211102' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux: x86/hyperv: Protect set_hv_tscchange_cb() against getting preempted Drivers: hv : vmbus: Adding NULL pointer check x86/hyperv: Remove duplicate include x86/hyperv: Remove duplicated include in hv_init Drivers: hv: vmbus: Remove unused code to check for subchannels Drivers: hv: vmbus: Initialize VMbus ring buffer for Isolation VM Drivers: hv: vmbus: Add SNP support for VMbus channel initiate message x86/hyperv: Add ghcb hvcall support for SNP VM x86/hyperv: Add Write/Read MSR registers via ghcb page Drivers: hv: vmbus: Mark vmbus ring buffer visible to host in Isolation VM x86/hyperv: Add new hvcall guest address host visibility support x86/hyperv: Initialize shared memory boundary in the Isolation VM. x86/hyperv: Initialize GHCB page in Isolation VM
2021-10-28Drivers: hv : vmbus: Adding NULL pointer checkLv Ruyi
This patch fixes the following Coccinelle warning: drivers/hv/ring_buffer.c:223: alloc with no test Reported-by: Zeal Robot <zealci@zte.com.cn> Signed-off-by: Lv Ruyi <lv.ruyi@zte.com.cn> Link: https://lore.kernel.org/r/20211028104138.14576-1-lv.ruyi@zte.com.cn Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-10-28Drivers: hv: vmbus: Remove unused code to check for subchannelsMichael Kelley
The last caller of vmbus_are_subchannels_present() was removed in commit c967590457ca ("scsi: storvsc: Fix a race in sub-channel creation that can cause panic"). Remove this dead code, and the utility function invoke_sc_cb() that it is the only caller of. Signed-off-by: Michael Kelley <mikelley@microsoft.com> Link: https://lore.kernel.org/r/1635191674-34407-1-git-send-email-mikelley@microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-10-28Drivers: hv: vmbus: Initialize VMbus ring buffer for Isolation VMTianyu Lan
VMbus ring buffer are shared with host and it's need to be accessed via extra address space of Isolation VM with AMD SNP support. This patch is to map the ring buffer address in extra address space via vmap_pfn(). Hyperv set memory host visibility hvcall smears data in the ring buffer and so reset the ring buffer memory to zero after mapping. Reviewed-by: Michael Kelley <mikelley@microsoft.com> Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com> Link: https://lore.kernel.org/r/20211025122116.264793-10-ltykernel@gmail.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-10-28Drivers: hv: vmbus: Add SNP support for VMbus channel initiate messageTianyu Lan
The monitor pages in the CHANNELMSG_INITIATE_CONTACT msg are shared with host in Isolation VM and so it's necessary to use hvcall to set them visible to host. In Isolation VM with AMD SEV SNP, the access address should be in the extra space which is above shared gpa boundary. So remap these pages into the extra address(pa + shared_gpa_boundary). Introduce monitor_pages_original[] in the struct vmbus_connection to store monitor page virtual address returned by hv_alloc_hyperv_ zeroed_page() and free monitor page via monitor_pages_original in the vmbus_disconnect(). The monitor_pages[] is to used to access monitor page and it is initialized to be equal with monitor_pages_ original. The monitor_pages[] will be overridden in the isolation VM with va of extra address. Introduce monitor_pages_pa[] to store monitor pages' physical address and use it to populate pa in the initiate msg. Reviewed-by: Michael Kelley <mikelley@microsoft.com> Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com> Link: https://lore.kernel.org/r/20211025122116.264793-9-ltykernel@gmail.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-10-28x86/hyperv: Add ghcb hvcall support for SNP VMTianyu Lan
hyperv provides ghcb hvcall to handle VMBus HVCALL_SIGNAL_EVENT and HVCALL_POST_MESSAGE msg in SNP Isolation VM. Add such support. Reviewed-by: Michael Kelley <mikelley@microsoft.com> Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com> Link: https://lore.kernel.org/r/20211025122116.264793-8-ltykernel@gmail.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-10-28x86/hyperv: Add Write/Read MSR registers via ghcb pageTianyu Lan
Hyperv provides GHCB protocol to write Synthetic Interrupt Controller MSR registers in Isolation VM with AMD SEV SNP and these registers are emulated by hypervisor directly. Hyperv requires to write SINTx MSR registers twice. First writes MSR via GHCB page to communicate with hypervisor and then writes wrmsr instruction to talk with paravisor which runs in VMPL0. Guest OS ID MSR also needs to be set via GHCB page. Reviewed-by: Michael Kelley <mikelley@microsoft.com> Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com> Link: https://lore.kernel.org/r/20211025122116.264793-7-ltykernel@gmail.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-10-28Drivers: hv: vmbus: Mark vmbus ring buffer visible to host in Isolation VMTianyu Lan
Mark vmbus ring buffer visible with set_memory_decrypted() when establish gpadl handle. Reviewed-by: Michael Kelley <mikelley@microsoft.com> Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com> Link: https://lore.kernel.org/r/20211025122116.264793-5-ltykernel@gmail.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-10-22Merge tag 'hyperv-fixes-signed-20211022' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux Pull hyper-v fix from Wei Liu: - Fix vmbus ARM64 build (Arnd Bergmann) * tag 'hyperv-fixes-signed-20211022' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux: hyperv/vmbus: include linux/bitops.h
2021-10-22hyperv/vmbus: include linux/bitops.hArnd Bergmann
On arm64 randconfig builds, hyperv sometimes fails with this error: In file included from drivers/hv/hv_trace.c:3: In file included from drivers/hv/hyperv_vmbus.h:16: In file included from arch/arm64/include/asm/sync_bitops.h:5: arch/arm64/include/asm/bitops.h:11:2: error: only <linux/bitops.h> can be included directly In file included from include/asm-generic/bitops/hweight.h:5: include/asm-generic/bitops/arch_hweight.h:9:9: error: implicit declaration of function '__sw_hweight32' [-Werror,-Wimplicit-function-declaration] include/asm-generic/bitops/atomic.h:17:7: error: implicit declaration of function 'BIT_WORD' [-Werror,-Wimplicit-function-declaration] Include the correct header first. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Link: https://lore.kernel.org/r/20211018131929.2260087-1-arnd@kernel.org Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-09-15Merge tag 'hyperv-fixes-signed-20210915' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux Pull hyperv fixes from Wei Liu: - Fix kernel crash caused by uio driver (Vitaly Kuznetsov) - Remove on-stack cpumask from HV APIC code (Wei Liu) * tag 'hyperv-fixes-signed-20210915' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux: x86/hyperv: remove on-stack cpumask from hv_send_ipi_mask_allbutself asm-generic/hyperv: provide cpumask_to_vpset_noself Drivers: hv: vmbus: Fix kernel crash upon unbinding a device from uio_hv_generic driver
2021-09-03Drivers: hv: vmbus: Fix kernel crash upon unbinding a device from ↵Vitaly Kuznetsov
uio_hv_generic driver The following crash happens when a never-used device is unbound from uio_hv_generic driver: kernel BUG at mm/slub.c:321! invalid opcode: 0000 [#1] SMP PTI CPU: 0 PID: 4001 Comm: bash Kdump: loaded Tainted: G X --------- --- 5.14.0-0.rc2.23.el9.x86_64 #1 Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine, BIOS 090008 12/07/2018 RIP: 0010:__slab_free+0x1d5/0x3d0 ... Call Trace: ? pick_next_task_fair+0x18e/0x3b0 ? __cond_resched+0x16/0x40 ? vunmap_pmd_range.isra.0+0x154/0x1c0 ? __vunmap+0x22d/0x290 ? hv_ringbuffer_cleanup+0x36/0x40 [hv_vmbus] kfree+0x331/0x380 ? hv_uio_remove+0x43/0x60 [uio_hv_generic] hv_ringbuffer_cleanup+0x36/0x40 [hv_vmbus] vmbus_free_ring+0x21/0x60 [hv_vmbus] hv_uio_remove+0x4f/0x60 [uio_hv_generic] vmbus_remove+0x23/0x30 [hv_vmbus] __device_release_driver+0x17a/0x230 device_driver_detach+0x3c/0xa0 unbind_store+0x113/0x130 ... The problem appears to be that we free 'ring_info->pkt_buffer' twice: first, when the device is unbound from in-kernel driver (netvsc in this case) and second from hv_uio_remove(). Normally, ring buffer is supposed to be re-initialized from hv_uio_open() but this happens when UIO device is being opened and this is not guaranteed to happen. Generally, it is OK to call hv_ringbuffer_cleanup() twice for the same channel (which is being handed over between in-kernel drivers and UIO) even if we didn't call hv_ringbuffer_init() in between. We, however, need to avoid kfree() call for an already freed pointer. Fixes: adae1e931acd ("Drivers: hv: vmbus: Copy packets sent by Hyper-V out of the ring buffer") Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Reviewed-by: Andrea Parri <parri.andrea@gmail.com> Reviewed-by: Michael Kelley <mikelley@microsoft.com> Link: https://lore.kernel.org/r/20210831143916.144983-1-vkuznets@redhat.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-09-01Merge tag 'hyperv-next-signed-20210831' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux Pull hyperv updates from Wei Liu: - make Hyper-V code arch-agnostic (Michael Kelley) - fix sched_clock behaviour on Hyper-V (Ani Sinha) - fix a fault when Linux runs as the root partition on MSHV (Praveen Kumar) - fix VSS driver (Vitaly Kuznetsov) - cleanup (Sonia Sharma) * tag 'hyperv-next-signed-20210831' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux: hv_utils: Set the maximum packet size for VSS driver to the length of the receive buffer Drivers: hv: Enable Hyper-V code to be built on ARM64 arm64: efi: Export screen_info arm64: hyperv: Initialize hypervisor on boot arm64: hyperv: Add panic handler arm64: hyperv: Add Hyper-V hypercall and register access utilities x86/hyperv: fix root partition faults when writing to VP assist page MSR hv: hyperv.h: Remove unused inline functions drivers: hv: Decouple Hyper-V clock/timer code from VMbus drivers x86/hyperv: add comment describing TSC_INVARIANT_CONTROL MSR setting bit 0 Drivers: hv: Move Hyper-V misc functionality to arch-neutral code Drivers: hv: Add arch independent default functions for some Hyper-V handlers Drivers: hv: Make portions of Hyper-V init code be arch neutral x86/hyperv: fix for unwanted manipulation of sched_clock when TSC marked unstable asm-generic/hyperv: Add missing #include of nmi.h
2021-08-25hv_utils: Set the maximum packet size for VSS driver to the length of the ↵Vitaly Kuznetsov
receive buffer Commit adae1e931acd ("Drivers: hv: vmbus: Copy packets sent by Hyper-V out of the ring buffer") introduced a notion of maximum packet size and for KVM and FCOPY drivers set it to the length of the receive buffer. VSS driver wasn't updated, this means that the maximum packet size is now VMBUS_DEFAULT_MAX_PKT_SIZE (4k). Apparently, this is not enough. I'm observing a packet of 6304 bytes which is being truncated to 4096. When VSS driver tries to read next packet from ring buffer it starts from the wrong offset and receives garbage. Set the maximum packet size to 'HV_HYP_PAGE_SIZE * 2' in VSS driver. This matches the length of the receive buffer and is in line with other utils drivers. Fixes: adae1e931acd ("Drivers: hv: vmbus: Copy packets sent by Hyper-V out of the ring buffer") Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Reviewed-by: Michael Kelley <mikelley@microsoft.com> Link: https://lore.kernel.org/r/20210825133857.847866-1-vkuznets@redhat.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-08-04Drivers: hv: Enable Hyper-V code to be built on ARM64Michael Kelley
Update drivers/hv/Kconfig so CONFIG_HYPERV can be selected on ARM64, causing the Hyper-V specific code to be built. Exclude the Hyper-V enlightened clocks/timers code from being built for ARM64. Signed-off-by: Michael Kelley <mikelley@microsoft.com> Reviewed-by: Boqun Feng <boqun.feng@gmail.com> Acked-by: Marc Zyngier <maz@kernel.org> Acked-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Link: https://lore.kernel.org/r/1628092359-61351-6-git-send-email-mikelley@microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-07-27Merge 5.14-rc3 into driver-core-nextGreg Kroah-Hartman
We need the driver-core fixes in here as well. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-07-21bus: Make remove callback return voidUwe Kleine-König
The driver core ignores the return value of this callback because there is only little it can do when a device disappears. This is the final bit of a long lasting cleanup quest where several buses were converted to also return void from their remove callback. Additionally some resource leaks were fixed that were caused by drivers returning an error code in the expectation that the driver won't go away. With struct bus_type::remove returning void it's prevented that newly implemented buses return an ignored error code and so don't anticipate wrong expectations for driver authors. Reviewed-by: Tom Rix <trix@redhat.com> (For fpga) Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org> Reviewed-by: Cornelia Huck <cohuck@redhat.com> (For drivers/s390 and drivers/vfio) Acked-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> (For ARM, Amba and related parts) Acked-by: Mark Brown <broonie@kernel.org> Acked-by: Chen-Yu Tsai <wens@csie.org> (for sunxi-rsb) Acked-by: Pali Rohár <pali@kernel.org> Acked-by: Mauro Carvalho Chehab <mchehab@kernel.org> (for media) Acked-by: Hans de Goede <hdegoede@redhat.com> (For drivers/platform) Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Acked-By: Vinod Koul <vkoul@kernel.org> Acked-by: Juergen Gross <jgross@suse.com> (For xen) Acked-by: Lee Jones <lee.jones@linaro.org> (For mfd) Acked-by: Johannes Thumshirn <jth@kernel.org> (For mcb) Acked-by: Johan Hovold <johan@kernel.org> Acked-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org> (For slimbus) Acked-by: Kirti Wankhede <kwankhede@nvidia.com> (For vfio) Acked-by: Maximilian Luz <luzmaximilian@gmail.com> Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> (For ulpi and typec) Acked-by: Samuel Iglesias Gonsálvez <siglesias@igalia.com> (For ipack) Acked-by: Geoff Levand <geoff@infradead.org> (For ps3) Acked-by: Yehezkel Bernat <YehezkelShB@gmail.com> (For thunderbolt) Acked-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> (For intel_th) Acked-by: Dominik Brodowski <linux@dominikbrodowski.net> (For pcmcia) Acked-by: Rafael J. Wysocki <rafael@kernel.org> (For ACPI) Acked-by: Bjorn Andersson <bjorn.andersson@linaro.org> (rpmsg and apr) Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> (For intel-ish-hid) Acked-by: Dan Williams <dan.j.williams@intel.com> (For CXL, DAX, and NVDIMM) Acked-by: William Breathitt Gray <vilhelm.gray@gmail.com> (For isa) Acked-by: Stefan Richter <stefanr@s5r6.in-berlin.de> (For firewire) Acked-by: Benjamin Tissoires <benjamin.tissoires@redhat.com> (For hid) Acked-by: Thorsten Scherer <t.scherer@eckelmann.de> (For siox) Acked-by: Sven Van Asbroeck <TheSven73@gmail.com> (For anybuss) Acked-by: Ulf Hansson <ulf.hansson@linaro.org> (For MMC) Acked-by: Wolfram Sang <wsa@kernel.org> # for I2C Acked-by: Sudeep Holla <sudeep.holla@arm.com> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> Acked-by: Finn Thain <fthain@linux-m68k.org> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Link: https://lore.kernel.org/r/20210713193522.1770306-6-u.kleine-koenig@pengutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-07-19Drivers: hv: vmbus: Fix duplicate CPU assignments within a deviceHaiyang Zhang
The vmbus module uses a rotational algorithm to assign target CPUs to a device's channels. Depending on the timing of different device's channel offers, different channels of a device may be assigned to the same CPU. For example on a VM with 2 CPUs, if NIC A and B's channels are offered in the following order, NIC A will have both channels on CPU0, and NIC B will have both channels on CPU1 -- see below. This kind of assignment causes RSS load that is spreading across different channels to end up on the same CPU. Timing of channel offers: NIC A channel 0 NIC B channel 0 NIC A channel 1 NIC B channel 1 VMBUS ID 14: Class_ID = {f8615163-df3e-46c5-913f-f2d2f965ed0e} - Synthetic network adapter Device_ID = {cab064cd-1f31-47d5-a8b4-9d57e320cccd} Sysfs path: /sys/bus/vmbus/devices/cab064cd-1f31-47d5-a8b4-9d57e320cccd Rel_ID=14, target_cpu=0 Rel_ID=17, target_cpu=0 VMBUS ID 16: Class_ID = {f8615163-df3e-46c5-913f-f2d2f965ed0e} - Synthetic network adapter Device_ID = {244225ca-743e-4020-a17d-d7baa13d6cea} Sysfs path: /sys/bus/vmbus/devices/244225ca-743e-4020-a17d-d7baa13d6cea Rel_ID=16, target_cpu=1 Rel_ID=18, target_cpu=1 Update the vmbus CPU assignment algorithm to avoid duplicate CPU assignments within a device. The new algorithm iterates num_online_cpus + 1 times. The existing rotational algorithm to find "next NUMA & CPU" is still here. But if the resulting CPU is already used by the same device, it will try the next CPU. In the last iteration, it assigns the channel to the next available CPU like the existing algorithm. This is not normally expected, because during device probe, we limit the number of channels of a device to be <= number of online CPUs. Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com> Reviewed-by: Michael Kelley <mikelley@microsoft.com> Tested-by: Michael Kelley <mikelley@microsoft.com> Link: https://lore.kernel.org/r/1626459673-17420-1-git-send-email-haiyangz@microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-07-19drivers: hv: Decouple Hyper-V clock/timer code from VMbus driversMichael Kelley
Hyper-V clock/timer code in hyperv_timer.c is mostly independent from other VMbus drivers, but building for ARM64 without hyperv_timer.c shows some remaining entanglements. A default implementation of hv_read_reference_counter can just read a Hyper-V synthetic register and be independent of hyperv_timer.c, so move this code out and into hv_common.c. Then it can be used by the timesync driver even if hyperv_timer.c isn't built on a particular architecture. If hyperv_timer.c *is* built, it can override with a faster implementation. Also provide stubs for stimer functions called by the VMbus driver when hyperv_timer.c isn't built. No functional changes. Signed-off-by: Michael Kelley <mikelley@microsoft.com> Link: https://lore.kernel.org/r/1626220906-22629-1-git-send-email-mikelley@microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-07-15Drivers: hv: Move Hyper-V misc functionality to arch-neutral codeMichael Kelley
The check for whether hibernation is possible, and the enabling of Hyper-V panic notification during kexec, are both architecture neutral. Move the code from under arch/x86 and into drivers/hv/hv_common.c where it can also be used for ARM64. No functional change. Signed-off-by: Michael Kelley <mikelley@microsoft.com> Link: https://lore.kernel.org/r/1626287687-2045-4-git-send-email-mikelley@microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-07-15Drivers: hv: Add arch independent default functions for some Hyper-V handlersMichael Kelley
Architecture independent Hyper-V code calls various arch-specific handlers when needed. To aid in supporting multiple architectures, provide weak defaults that can be overridden by arch-specific implementations where appropriate. But when arch-specific overrides aren't needed or haven't been implemented yet for a particular architecture, these stubs reduce the amount of clutter under arch/. No functional change. Signed-off-by: Michael Kelley <mikelley@microsoft.com> Link: https://lore.kernel.org/r/1626287687-2045-3-git-send-email-mikelley@microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-07-15Drivers: hv: Make portions of Hyper-V init code be arch neutralMichael Kelley
The code to allocate and initialize the hv_vp_index array is architecture neutral. Similarly, the code to allocate and populate the hypercall input and output arg pages is architecture neutral. Move both sets of code out from arch/x86 and into utility functions in drivers/hv/hv_common.c that can be shared by Hyper-V initialization on ARM64. No functional changes. However, the allocation of the hypercall input and output arg pages is done differently so that the size is always the Hyper-V page size, even if not the same as the guest page size (such as with ARM64's 64K page size). Signed-off-by: Michael Kelley <mikelley@microsoft.com> Link: https://lore.kernel.org/r/1626287687-2045-2-git-send-email-mikelley@microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-07-02Merge branch 'akpm' (patches from Andrew)Linus Torvalds
Merge more updates from Andrew Morton: "190 patches. Subsystems affected by this patch series: mm (hugetlb, userfaultfd, vmscan, kconfig, proc, z3fold, zbud, ras, mempolicy, memblock, migration, thp, nommu, kconfig, madvise, memory-hotplug, zswap, zsmalloc, zram, cleanups, kfence, and hmm), procfs, sysctl, misc, core-kernel, lib, lz4, checkpatch, init, kprobes, nilfs2, hfs, signals, exec, kcov, selftests, compress/decompress, and ipc" * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (190 commits) ipc/util.c: use binary search for max_idx ipc/sem.c: use READ_ONCE()/WRITE_ONCE() for use_global_lock ipc: use kmalloc for msg_queue and shmid_kernel ipc sem: use kvmalloc for sem_undo allocation lib/decompressors: remove set but not used variabled 'level' selftests/vm/pkeys: exercise x86 XSAVE init state selftests/vm/pkeys: refill shadow register after implicit kernel write selftests/vm/pkeys: handle negative sys_pkey_alloc() return code selftests/vm/pkeys: fix alloc_random_pkey() to make it really, really random kcov: add __no_sanitize_coverage to fix noinstr for all architectures exec: remove checks in __register_bimfmt() x86: signal: don't do sas_ss_reset() until we are certain that sigframe won't be abandoned hfsplus: report create_date to kstat.btime hfsplus: remove unnecessary oom message nilfs2: remove redundant continue statement in a while-loop kprobes: remove duplicated strong free_insn_page in x86 and s390 init: print out unknown kernel parameters checkpatch: do not complain about positive return values starting with EPOLL checkpatch: improve the indented label test checkpatch: scripts/spdxcheck.py now requires python3 ...
2021-07-01kernel.h: split out panic and oops helpersAndy Shevchenko
kernel.h is being used as a dump for all kinds of stuff for a long time. Here is the attempt to start cleaning it up by splitting out panic and oops helpers. There are several purposes of doing this: - dropping dependency in bug.h - dropping a loop by moving out panic_notifier.h - unload kernel.h from something which has its own domain At the same time convert users tree-wide to use new headers, although for the time being include new header back to kernel.h to avoid twisted indirected includes for existing users. [akpm@linux-foundation.org: thread_info.h needs limits.h] [andriy.shevchenko@linux.intel.com: ia64 fix] Link: https://lkml.kernel.org/r/20210520130557.55277-1-andriy.shevchenko@linux.intel.com Link: https://lkml.kernel.org/r/20210511074137.33666-1-andriy.shevchenko@linux.intel.com Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org> Co-developed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Mike Rapoport <rppt@linux.ibm.com> Acked-by: Corey Minyard <cminyard@mvista.com> Acked-by: Christian Brauner <christian.brauner@ubuntu.com> Acked-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Wei Liu <wei.liu@kernel.org> Acked-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Sebastian Reichel <sre@kernel.org> Acked-by: Luis Chamberlain <mcgrof@kernel.org> Acked-by: Stephen Boyd <sboyd@kernel.org> Acked-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Acked-by: Helge Deller <deller@gmx.de> # parisc Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-29Merge tag 'hyperv-next-signed-20210629' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux Pull hyperv updates from Wei Liu: "Just a few minor enhancement patches and bug fixes" * tag 'hyperv-next-signed-20210629' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux: PCI: hv: Add check for hyperv_initialized in init_hv_pci_drv() Drivers: hv: Move Hyper-V extended capability check to arch neutral code drivers: hv: Fix missing error code in vmbus_connect() x86/hyperv: fix logical processor creation hv_utils: Fix passing zero to 'PTR_ERR' warning scsi: storvsc: Use blk_mq_unique_tag() to generate requestIDs Drivers: hv: vmbus: Copy packets sent by Hyper-V out of the ring buffer hv_balloon: Remove redundant assignment to region_start
2021-06-05Drivers: hv: Move Hyper-V extended capability check to arch neutral codeMichael Kelley
The extended capability query code is currently under arch/x86, but it is architecture neutral, and is used by arch neutral code in the Hyper-V balloon driver. Hence the balloon driver fails to build on other architectures. Fix by moving the ext cap code out from arch/x86. Because it is also called from built-in architecture specific code, it can't be in a module, so the Makefile treats as built-in even when CONFIG_HYPERV is "m". Also drivers/Makefile is tweaked because this is the first occurrence of a Hyper-V file that is built-in even when CONFIG_HYPERV is "m". While here, update the hypercall status check to use the new helper function instead of open coding. No functional change. Signed-off-by: Michael Kelley <mikelley@microsoft.com> Reviewed-by: Sunil Muthuswamy <sunilmut@microsoft.com> Link: https://lore.kernel.org/r/1622669804-2016-1-git-send-email-mikelley@microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-06-02drivers: hv: Fix missing error code in vmbus_connect()Jiapeng Chong
Eliminate the follow smatch warning: drivers/hv/connection.c:236 vmbus_connect() warn: missing error code 'ret'. Reported-by: Abaci Robot <abaci@linux.alibaba.com> Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com> Reviewed-by: Michael Kelley <mikelley@microsoft.com> Link: https://lore.kernel.org/r/1621940321-72353-1-git-send-email-jiapeng.chong@linux.alibaba.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-05-18hv_utils: Fix passing zero to 'PTR_ERR' warningYueHaibing
Sparse warn this: drivers/hv/hv_util.c:753 hv_timesync_init() warn: passing zero to 'PTR_ERR' Use PTR_ERR_OR_ZERO instead of PTR_ERR to fix this. Signed-off-by: YueHaibing <yuehaibing@huawei.com> Link: https://lore.kernel.org/r/20210514070116.16800-1-yuehaibing@huawei.com [ wei: change %ld to %d ] Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-05-14scsi: storvsc: Use blk_mq_unique_tag() to generate requestIDsAndrea Parri (Microsoft)
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 <mikelley@microsoft.com> Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com> Reviewed-by: Michael Kelley <mikelley@microsoft.com> Acked-by: Martin K. Petersen <martin.petersen@oracle.com> Link: https://lore.kernel.org/r/20210510210841.370472-1-parri.andrea@gmail.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-05-14Drivers: hv: vmbus: Copy packets sent by Hyper-V out of the ring bufferAndres Beltran
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 <lkmlabelt@gmail.com> Co-developed-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com> Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com> Reviewed-by: Michael Kelley <mikelley@microsoft.com> Link: https://lore.kernel.org/r/20210408161439.341988-1-parri.andrea@gmail.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-05-14hv_balloon: Remove redundant assignment to region_startJiapeng Chong
Variable region_start is set to pg_start but this value is never read as it is overwritten later on, hence it is a redundant assignment and can be removed. Cleans up the following clang-analyzer warning: drivers/hv/hv_balloon.c:1013:3: warning: Value stored to 'region_start' is never read [clang-analyzer-deadcode.DeadStores]. Reported-by: Abaci Robot <abaci@linux.alibaba.com> Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com> Link: https://lore.kernel.org/r/1619691681-86256-1-git-send-email-jiapeng.chong@linux.alibaba.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-04-27Merge tag 'printk-for-5.13' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux Pull printk updates from Petr Mladek: - Stop synchronizing kernel log buffer readers by logbuf_lock. As a result, the access to the buffer is fully lockless now. Note that printk() itself still uses locks because it tries to flush the messages to the console immediately. Also the per-CPU temporary buffers are still there because they prevent infinite recursion and serialize backtraces from NMI. All this is going to change in the future. - kmsg_dump API rework and cleanup as a side effect of the logbuf_lock removal. - Make bstr_printf() aware that %pf and %pF formats could deference the given pointer. - Show also page flags by %pGp format. - Clarify the documentation for plain pointer printing. - Do not show no_hash_pointers warning multiple times. - Update Senozhatsky email address. - Some clean up. * tag 'printk-for-5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: (24 commits) lib/vsprintf.c: remove leftover 'f' and 'F' cases from bstr_printf() printk: clarify the documentation for plain pointer printing kernel/printk.c: Fixed mundane typos printk: rename vprintk_func to vprintk vsprintf: dump full information of page flags in pGp mm, slub: don't combine pr_err with INFO mm, slub: use pGp to print page flags MAINTAINERS: update Senozhatsky email address lib/vsprintf: do not show no_hash_pointers message multiple times printk: console: remove unnecessary safe buffer usage printk: kmsg_dump: remove _nolock() variants printk: remove logbuf_lock printk: introduce a kmsg_dump iterator printk: kmsg_dumper: remove @active field printk: add syslog_lock printk: use atomic64_t for devkmsg_user.seq printk: use seqcount_latch for clear_seq printk: introduce CONSOLE_LOG_MAX printk: consolidate kmsg_dump_get_buffer/syslog_print_all code printk: refactor kmsg_dump_get_buffer() ...
2021-04-21drivers: hv: Create a consistent pattern for checking Hyper-V hypercall statusJoseph Salisbury
There is not a consistent pattern for checking Hyper-V hypercall status. Existing code uses a number of variants. The variants work, but a consistent pattern would improve the readability of the code, and be more conformant to what the Hyper-V TLFS says about hypercall status. Implemented new helper functions hv_result(), hv_result_success(), and hv_repcomp(). Changed the places where hv_do_hypercall() and related variants are used to use the helper functions. Signed-off-by: Joseph Salisbury <joseph.salisbury@microsoft.com> Reviewed-by: Michael Kelley <mikelley@microsoft.com> Link: https://lore.kernel.org/r/1618620183-9967-2-git-send-email-joseph.salisbury@linux.microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-04-20Drivers: hv: vmbus: Increase wait time for VMbus unloadMichael Kelley
When running in Azure, disks may be connected to a Linux VM with read/write caching enabled. If a VM panics and issues a VMbus UNLOAD request to Hyper-V, the response is delayed until all dirty data in the disk cache is flushed. In extreme cases, this flushing can take 10's of seconds, depending on the disk speed and the amount of dirty data. If kdump is configured for the VM, the current 10 second timeout in vmbus_wait_for_unload() may be exceeded, and the UNLOAD complete message may arrive well after the kdump kernel is already running, causing problems. Note that no problem occurs if kdump is not enabled because Hyper-V waits for the cache flush before doing a reboot through the BIOS/UEFI code. Fix this problem by increasing the timeout in vmbus_wait_for_unload() to 100 seconds. Also output periodic messages so that if anyone is watching the serial console, they won't think the VM is completely hung. Fixes: 911e1987efc8 ("Drivers: hv: vmbus: Add timeout to vmbus_wait_for_unload") Signed-off-by: Michael Kelley <mikelley@microsoft.com> Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com> Link: https://lore.kernel.org/r/1618894089-126662-1-git-send-email-mikelley@microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-04-20Drivers: hv: vmbus: Initialize unload_event staticallyAndrea Parri (Microsoft)
If a malicious or compromised Hyper-V sends a spurious message of type CHANNELMSG_UNLOAD_RESPONSE, the function vmbus_unload_response() will call complete() on an uninitialized event, and cause an oops. Reported-by: Michael Kelley <mikelley@microsoft.com> Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com> Reviewed-by: Michael Kelley <mikelley@microsoft.com> Link: https://lore.kernel.org/r/20210420014350.2002-1-parri.andrea@gmail.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-04-18Drivers: hv: vmbus: Check for pending channel interrupts before taking a CPU ↵Andrea Parri (Microsoft)
offline Check that enough time has passed such that the modify channel message has been processed before taking a CPU offline. Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com> Reviewed-by: Michael Kelley <mikelley@microsoft.com> Link: https://lore.kernel.org/r/20210416143449.16185-4-parri.andrea@gmail.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-04-18Drivers: hv: vmbus: Drivers: hv: vmbus: Introduce ↵Andrea Parri (Microsoft)
CHANNELMSG_MODIFYCHANNEL_RESPONSE Introduce the CHANNELMSG_MODIFYCHANNEL_RESPONSE message type, and code to receive and process such a message. Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com> Reviewed-by: Michael Kelley <mikelley@microsoft.com> Link: https://lore.kernel.org/r/20210416143449.16185-3-parri.andrea@gmail.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-04-18Drivers: hv: vmbus: Introduce and negotiate VMBus protocol version 5.3Andrea Parri (Microsoft)
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) <parri.andrea@gmail.com> Reviewed-by: Michael Kelley <mikelley@microsoft.com> Link: https://lore.kernel.org/r/20210416143449.16185-2-parri.andrea@gmail.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-04-16Drivers: hv: vmbus: Use after free in __vmbus_open()Dan Carpenter
The "open_info" variable is added to the &vmbus_connection.chn_msg_list, but the error handling frees "open_info" without removing it from the list. This will result in a use after free. First remove it from the list, and then free it. Fixes: 6f3d791f3006 ("Drivers: hv: vmbus: Fix rescind handling issues") Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Reviewed-by: Andrea Parri <parri.andrea@gmail.com> Link: https://lore.kernel.org/r/YHV3XLCot6xBS44r@mwanda Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-04-14Drivers: hv: vmbus: remove unused functionJiapeng Chong
Fix the following clang warning: drivers/hv/ring_buffer.c:89:1: warning: unused function 'hv_set_next_read_location' [-Wunused-function]. Reported-by: Abaci Robot <abaci@linux.alibaba.com> Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com> Reviewed-by: Michael Kelley <mikelley@microsoft.com> Link: https://lore.kernel.org/r/1618381282-119135-1-git-send-email-jiapeng.chong@linux.alibaba.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-04-02Drivers: hv: vmbus: Remove unused linux/version.h headerQiheng Lin
That file is not needed in hv.c. Reported-by: Hulk Robot <hulkci@huawei.com> Signed-off-by: Qiheng Lin <linqiheng@huawei.com> Link: https://lore.kernel.org/r/20210331060646.2471-1-linqiheng@huawei.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-03-24x86/Hyper-V: Support for free page reportingSunil Muthuswamy
Linux has support for free page reporting now (36e66c554b5c) for virtualized environment. On Hyper-V when virtually backed VMs are configured, Hyper-V will advertise cold memory discard capability, when supported. This patch adds the support to hook into the free page reporting infrastructure and leverage the Hyper-V cold memory discard hint hypercall to report/free these pages back to the host. Signed-off-by: Sunil Muthuswamy <sunilmut@microsoft.com> Tested-by: Matheus Castello <matheus@castello.eng.br> Reviewed-by: Michael Kelley <mikelley@microsoft.com> Tested-by: Nathan Chancellor <nathan@kernel.org> Link: https://lore.kernel.org/r/SN4PR2101MB0880121FA4E2FEC67F35C1DCC0649@SN4PR2101MB0880.namprd21.prod.outlook.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-03-22drivers: hv: Fix EXPORT_SYMBOL and tab spaces issueVasanth
1.Fixed EXPORT_SYMBOL should be follow immediately function/variable. 2.Fixed code tab spaces issue. Signed-off-by: Vasanth M <vasanth3g@gmail.com> Link: https://lore.kernel.org/r/20210310052155.39460-1-vasanth3g@gmail.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-03-22Drivers: hv: vmbus: Drop error message when 'No request id available'Andrea Parri (Microsoft)
Running out of request IDs on a channel essentially produces the same effect as running out of space in the ring buffer, in that -EAGAIN is returned. The error message in hv_ringbuffer_write() should either be dropped (since we don't output a message when the ring buffer is full) or be made conditional/debug-only. Suggested-by: Michael Kelley <mikelley@microsoft.com> Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com> Fixes: e8b7db38449ac ("Drivers: hv: vmbus: Add vmbus_requestor data structure for VMBus hardening") Link: https://lore.kernel.org/r/20210301191348.196485-1-parri.andrea@gmail.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-03-08Drivers: hv: vmbus: Move handling of VMbus interruptsMichael Kelley
VMbus interrupts are most naturally modelled as per-cpu IRQs. But because x86/x64 doesn't have per-cpu IRQs, the core VMbus interrupt handling machinery is done in code under arch/x86 and Linux IRQs are not used. Adding support for ARM64 means adding equivalent code using per-cpu IRQs under arch/arm64. A better model is to treat per-cpu IRQs as the normal path (which it is for modern architectures), and the x86/x64 path as the exception. Do this by incorporating standard Linux per-cpu IRQ allocation into the main VMbus driver, and bypassing it in the x86/x64 exception case. For x86/x64, special case code is retained under arch/x86, but no VMbus interrupt handling code is needed under arch/arm64. No functional change. Signed-off-by: Michael Kelley <mikelley@microsoft.com> Reviewed-by: Boqun Feng <boqun.feng@gmail.com> Link: https://lore.kernel.org/r/1614721102-2241-7-git-send-email-mikelley@microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-03-08Drivers: hv: vmbus: Handle auto EOI quirk inlineMichael Kelley
On x86/x64, Hyper-V provides a flag to indicate auto EOI functionality, but it doesn't on ARM64. Handle this quirk inline instead of calling into code under arch/x86 (and coming, under arch/arm64). No functional change. Signed-off-by: Michael Kelley <mikelley@microsoft.com> Reviewed-by: Boqun Feng <boqun.feng@gmail.com> Link: https://lore.kernel.org/r/1614721102-2241-6-git-send-email-mikelley@microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-03-08Drivers: hv: vmbus: Move hyperv_report_panic_msg to arch neutral codeMichael Kelley
With the new Hyper-V MSR set function, hyperv_report_panic_msg() can be architecture neutral, so move it out from under arch/x86 and merge into hv_kmsg_dump(). This move also avoids needing a separate implementation under arch/arm64. No functional change. Signed-off-by: Michael Kelley <mikelley@microsoft.com> Reviewed-by: Boqun Feng <boqun.feng@gmail.com> Link: https://lore.kernel.org/r/1614721102-2241-5-git-send-email-mikelley@microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-03-08Drivers: hv: Redo Hyper-V synthetic MSR get/set functionsMichael Kelley
Current code defines a separate get and set macro for each Hyper-V synthetic MSR used by the VMbus driver. Furthermore, the get macro can't be converted to a standard function because the second argument is modified in place, which is somewhat bad form. Redo this by providing a single get and a single set function that take a parameter specifying the MSR to be operated on. Fixup usage of the get function. Calling locations are no more complex than before, but the code under arch/x86 and the upcoming code under arch/arm64 is significantly simplified. Also standardize the names of Hyper-V synthetic MSRs that are architecture neutral. But keep the old x86-specific names as aliases that can be removed later when all references (particularly in KVM code) have been cleaned up in a separate patch series. No functional change. Signed-off-by: Michael Kelley <mikelley@microsoft.com> Reviewed-by: Boqun Feng <boqun.feng@gmail.com> Link: https://lore.kernel.org/r/1614721102-2241-4-git-send-email-mikelley@microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org>