1 files changed, 27 insertions, 0 deletions
diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 595e44e8abaa..9c70018a9906 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -423,6 +423,33 @@ void hyperv_report_panic(struct pt_regs *regs, long err)
 }
 EXPORT_SYMBOL_GPL(hyperv_report_panic);
 
+/**
+ * hyperv_report_panic_msg - report panic message to Hyper-V
+ * @pa: physical address of the panic page containing the message
+ * @size: size of the message in the page
+ */
+void hyperv_report_panic_msg(phys_addr_t pa, size_t size)
+{
+	/*
+	 * P3 to contain the physical address of the panic page & P4 to
+	 * contain the size of the panic data in that page. Rest of the
+	 * registers are no-op when the NOTIFY_MSG flag is set.
+	 */
+	wrmsrl(HV_X64_MSR_CRASH_P0, 0);
+	wrmsrl(HV_X64_MSR_CRASH_P1, 0);
+	wrmsrl(HV_X64_MSR_CRASH_P2, 0);
+	wrmsrl(HV_X64_MSR_CRASH_P3, pa);
+	wrmsrl(HV_X64_MSR_CRASH_P4, size);
+
+	/*
+	 * Let Hyper-V know there is crash data available along with
+	 * the panic message.
+	 */
+	wrmsrl(HV_X64_MSR_CRASH_CTL,
+	       (HV_CRASH_CTL_CRASH_NOTIFY | HV_CRASH_CTL_CRASH_NOTIFY_MSG));
+}
+EXPORT_SYMBOL_GPL(hyperv_report_panic_msg);
+
 bool hv_is_hyperv_initialized(void)
 {
 	union hv_x64_msr_hypercall_contents hypercall_msr;