Messages in this thread | | | Date | Tue, 23 May 2023 18:54:05 +0000 | From | Wei Liu <> | Subject | Re: [PATCH v2 1/1] Drivers: hv: vmbus: Fix vmbus_wait_for_unload() to scan present CPUs |
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On Thu, May 18, 2023 at 08:13:52AM -0700, Michael Kelley wrote: > vmbus_wait_for_unload() may be called in the panic path after other > CPUs are stopped. vmbus_wait_for_unload() currently loops through > online CPUs looking for the UNLOAD response message. But the values of > CONFIG_KEXEC_CORE and crash_kexec_post_notifiers affect the path used > to stop the other CPUs, and in one of the paths the stopped CPUs > are removed from cpu_online_mask. This removal happens in both > x86/x64 and arm64 architectures. In such a case, vmbus_wait_for_unload() > only checks the panic'ing CPU, and misses the UNLOAD response message > except when the panic'ing CPU is CPU 0. vmbus_wait_for_unload() > eventually times out, but only after waiting 100 seconds. > > Fix this by looping through *present* CPUs in vmbus_wait_for_unload(). > The cpu_present_mask is not modified by stopping the other CPUs in the > panic path, nor should it be. > > Also, in a CoCo VM the synic_message_page is not allocated in > hv_synic_alloc(), but is set and cleared in hv_synic_enable_regs() > and hv_synic_disable_regs() such that it is set only when the CPU is > online. If not all present CPUs are online when vmbus_wait_for_unload() > is called, the synic_message_page might be NULL. Add a check for this. > > Fixes: cd95aad55793 ("Drivers: hv: vmbus: handle various crash scenarios") > Cc: stable@vger.kernel.org > Reported-by: John Starks <jostarks@microsoft.com> > Signed-off-by: Michael Kelley <mikelley@microsoft.com> > Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Applied to hyperv-fixes. Thanks.
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