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authorMichael Kelley <mikelley@microsoft.com>2023-05-18 18:13:52 +0300
committerWei Liu <wei.liu@kernel.org>2023-05-23 21:53:16 +0300
commit320805ab61e5f1e2a5729ae266e16bec2904050c (patch)
treed23598814e22eb256c4f0887b875f386db82db49 /drivers/hv
parentec97e112985c2581ee61854a4b74f080f6cdfc2c (diff)
downloadlinux-320805ab61e5f1e2a5729ae266e16bec2904050c.tar.xz
Drivers: hv: vmbus: Fix vmbus_wait_for_unload() to scan present CPUs
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> Link: https://lore.kernel.org/r/1684422832-38476-1-git-send-email-mikelley@microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
Diffstat (limited to 'drivers/hv')
-rw-r--r--drivers/hv/channel_mgmt.c18
1 files changed, 16 insertions, 2 deletions
diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index 007f26d5f1a4..2f4d09ce027a 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -829,11 +829,22 @@ static void vmbus_wait_for_unload(void)
if (completion_done(&vmbus_connection.unload_event))
goto completed;
- for_each_online_cpu(cpu) {
+ for_each_present_cpu(cpu) {
struct hv_per_cpu_context *hv_cpu
= per_cpu_ptr(hv_context.cpu_context, cpu);
+ /*
+ * In a CoCo VM the synic_message_page is not allocated
+ * in hv_synic_alloc(). Instead it is set/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, the message page
+ * might be NULL, so skip such CPUs.
+ */
page_addr = hv_cpu->synic_message_page;
+ if (!page_addr)
+ continue;
+
msg = (struct hv_message *)page_addr
+ VMBUS_MESSAGE_SINT;
@@ -867,11 +878,14 @@ completed:
* maybe-pending messages on all CPUs to be able to receive new
* messages after we reconnect.
*/
- for_each_online_cpu(cpu) {
+ for_each_present_cpu(cpu) {
struct hv_per_cpu_context *hv_cpu
= per_cpu_ptr(hv_context.cpu_context, cpu);
page_addr = hv_cpu->synic_message_page;
+ if (!page_addr)
+ continue;
+
msg = (struct hv_message *)page_addr + VMBUS_MESSAGE_SINT;
msg->header.message_type = HVMSG_NONE;
}