linux/drivers/hv
Michael Kelley 9636be85cc x86/hyperv: Fix hyperv_pcpu_input_arg handling when CPUs go online/offline
These commits

a494aef23d ("PCI: hv: Replace retarget_msi_interrupt_params with hyperv_pcpu_input_arg")
2c6ba42168 ("PCI: hv: Enable PCI pass-thru devices in Confidential VMs")

update the Hyper-V virtual PCI driver to use the hyperv_pcpu_input_arg
because that memory will be correctly marked as decrypted or encrypted
for all VM types (CoCo or normal). But problems ensue when CPUs in the
VM go online or offline after virtual PCI devices have been configured.

When a CPU is brought online, the hyperv_pcpu_input_arg for that CPU is
initialized by hv_cpu_init() running under state CPUHP_AP_ONLINE_DYN.
But this state occurs after state CPUHP_AP_IRQ_AFFINITY_ONLINE, which
may call the virtual PCI driver and fault trying to use the as yet
uninitialized hyperv_pcpu_input_arg. A similar problem occurs in a CoCo
VM if the MMIO read and write hypercalls are used from state
CPUHP_AP_IRQ_AFFINITY_ONLINE.

When a CPU is taken offline, IRQs may be reassigned in state
CPUHP_TEARDOWN_CPU. Again, the virtual PCI driver may fault trying to
use the hyperv_pcpu_input_arg that has already been freed by a
higher state.

Fix the onlining problem by adding state CPUHP_AP_HYPERV_ONLINE
immediately after CPUHP_AP_ONLINE_IDLE (similar to CPUHP_AP_KVM_ONLINE)
and before CPUHP_AP_IRQ_AFFINITY_ONLINE. Use this new state for
Hyper-V initialization so that hyperv_pcpu_input_arg is allocated
early enough.

Fix the offlining problem by not freeing hyperv_pcpu_input_arg when
a CPU goes offline. Retain the allocated memory, and reuse it if
the CPU comes back online later.

Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Acked-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Dexuan Cui <decui@microsoft.com>
Link: https://lore.kernel.org/r/1684862062-51576-1-git-send-email-mikelley@microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
2023-06-17 23:09:47 +00:00
..
channel_mgmt.c Drivers: hv: vmbus: Fix vmbus_wait_for_unload() to scan present CPUs 2023-05-23 18:53:16 +00:00
channel.c Drivers: hv: vmbus: Introduce {lock,unlock}_requestor() 2022-04-25 15:51:13 +00:00
connection.c Drivers: hv: vmbus: Remove second mapping of VMBus monitor pages 2023-04-17 19:19:04 +00:00
hv_balloon.c hyperv-next for v6.3. 2023-02-21 16:59:23 -08:00
hv_common.c x86/hyperv: Fix hyperv_pcpu_input_arg handling when CPUs go online/offline 2023-06-17 23:09:47 +00:00
hv_debugfs.c hv_debugfs: Make hv_debug_root static 2020-04-04 17:47:43 +01:00
hv_fcopy.c Drivers: hv: remove duplicate word in a comment 2022-09-05 16:28:40 +00:00
hv_kvp.c Drivers: hv: Fix syntax errors in comments 2022-06-08 12:26:28 +00:00
hv_snapshot.c hv_utils: Add comment about max VMbus packet size in VSS driver 2022-02-18 13:08:18 +00:00
hv_trace_balloon.h hv_balloon: trace post_status 2018-03-06 09:57:17 -08:00
hv_trace.c hv: add SPDX license to trace 2018-03-28 13:24:56 +02:00
hv_trace.h Drivers: hv: vmbus: Drivers: hv: vmbus: Introduce CHANNELMSG_MODIFYCHANNEL_RESPONSE 2021-04-18 13:03:11 +00:00
hv_util.c Drivers: hv: Make remove callback of hyperv driver void returned 2023-01-17 13:41:27 +00:00
hv_utils_transport.c Drivers: hv: utils: Make use of the helper macro LIST_HEAD() 2022-02-09 14:33:21 +00:00
hv_utils_transport.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 280 2019-06-05 17:36:36 +02:00
hv.c Drivers: hv: move panic report code from vmbus to hv early init code 2023-04-20 23:00:37 +00:00
hyperv_vmbus.h Drivers: hv: vmbus: Remove the per-CPU post_msg_page 2023-04-17 19:19:05 +00:00
Kconfig Drivers: hv: Kconfig: Add HYPERV_VTL_MODE 2023-04-18 17:29:52 +00:00
Makefile Drivers: hv: Move Hyper-V extended capability check to arch neutral code 2021-06-05 10:22:34 +00:00
ring_buffer.c Drivers: hv: vmbus: Remove second way of mapping ring buffers 2023-04-17 19:19:04 +00:00
vmbus_drv.c Drivers: hv: vmbus: Call hv_synic_free() if hv_synic_alloc() fails 2023-05-08 17:37:20 +00:00