[PATCH 28/41] Drivers: hv: Add arch independent default functions for some Hyper-V handlers

[Tim Gardner]

From: Michael Kelley <mikelley at microsoft.com>

BugLink: https://bugs.launchpad.net/bugs/1949770

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 at microsoft.com>
Link: https://lore.kernel.org/r/1626287687-2045-3-git-send-email-mikelley@microsoft.com
Signed-off-by: Wei Liu <wei.liu at kernel.org>
(backported from commit 9d7cf2c9675838c12cd5cf5a4ebe2ba41bd78a44)
Signed-off-by: Tim Gardner <tim.gardner at canonical.com>
[rtg - minor context adjustment, added hv_is_isolation_supported() definition to
include/asm-generic/mshyperv.h]
---
 arch/x86/hyperv/hv_init.c      |  1 -
 arch/x86/kernel/cpu/mshyperv.c |  6 -----
 drivers/hv/hv_common.c         | 49 ++++++++++++++++++++++++++++++++++
 include/asm-generic/mshyperv.h |  1 +
 4 files changed, 50 insertions(+), 7 deletions(-)

diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 08284bfca479..4924d8c03228 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -410,7 +410,6 @@ void hyperv_cleanup(void)
 	hypercall_msr.as_uint64 = 0;
 	wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64);
 }
-EXPORT_SYMBOL_GPL(hyperv_cleanup);
 
 void hyperv_report_panic(struct pt_regs *regs, long err, bool in_die)
 {
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index ea7091596d73..44891430ea1c 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -60,14 +60,12 @@ void hv_setup_vmbus_handler(void (*handler)(void))
 {
 	vmbus_handler = handler;
 }
-EXPORT_SYMBOL_GPL(hv_setup_vmbus_handler);
 
 void hv_remove_vmbus_handler(void)
 {
 	/* We have no way to deallocate the interrupt gate */
 	vmbus_handler = NULL;
 }
-EXPORT_SYMBOL_GPL(hv_remove_vmbus_handler);
 
 /*
  * Routines to do per-architecture handling of stimer0
@@ -102,25 +100,21 @@ void hv_setup_kexec_handler(void (*handler)(void))
 {
 	hv_kexec_handler = handler;
 }
-EXPORT_SYMBOL_GPL(hv_setup_kexec_handler);
 
 void hv_remove_kexec_handler(void)
 {
 	hv_kexec_handler = NULL;
 }
-EXPORT_SYMBOL_GPL(hv_remove_kexec_handler);
 
 void hv_setup_crash_handler(void (*handler)(struct pt_regs *regs))
 {
 	hv_crash_handler = handler;
 }
-EXPORT_SYMBOL_GPL(hv_setup_crash_handler);
 
 void hv_remove_crash_handler(void)
 {
 	hv_crash_handler = NULL;
 }
-EXPORT_SYMBOL_GPL(hv_remove_crash_handler);
 
 #ifdef CONFIG_KEXEC_CORE
 static void hv_machine_shutdown(void)
diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
index caba4f728987..cac9c6bfc653 100644
--- a/drivers/hv/hv_common.c
+++ b/drivers/hv/hv_common.c
@@ -16,6 +16,7 @@
 #include <linux/export.h>
 #include <linux/bitfield.h>
 #include <linux/cpumask.h>
+#include <linux/ptrace.h>
 #include <linux/slab.h>
 #include <asm/hyperv-tlfs.h>
 #include <asm/mshyperv.h>
@@ -202,3 +203,51 @@ bool hv_query_ext_cap(u64 cap_query)
 	return hv_extended_cap & cap_query;
 }
 EXPORT_SYMBOL_GPL(hv_query_ext_cap);
+
+/* These __weak functions provide default "no-op" behavior and
+ * may be overridden by architecture specific versions. Architectures
+ * for which the default "no-op" behavior is sufficient can leave
+ * them unimplemented and not be cluttered with a bunch of stub
+ * functions in arch-specific code.
+ */
+
+bool __weak hv_is_isolation_supported(void)
+{
+	return false;
+}
+EXPORT_SYMBOL_GPL(hv_is_isolation_supported);
+
+void __weak hv_setup_vmbus_handler(void (*handler)(void))
+{
+}
+EXPORT_SYMBOL_GPL(hv_setup_vmbus_handler);
+
+void __weak hv_remove_vmbus_handler(void)
+{
+}
+EXPORT_SYMBOL_GPL(hv_remove_vmbus_handler);
+
+void __weak hv_setup_kexec_handler(void (*handler)(void))
+{
+}
+EXPORT_SYMBOL_GPL(hv_setup_kexec_handler);
+
+void __weak hv_remove_kexec_handler(void)
+{
+}
+EXPORT_SYMBOL_GPL(hv_remove_kexec_handler);
+
+void __weak hv_setup_crash_handler(void (*handler)(struct pt_regs *regs))
+{
+}
+EXPORT_SYMBOL_GPL(hv_setup_crash_handler);
+
+void __weak hv_remove_crash_handler(void)
+{
+}
+EXPORT_SYMBOL_GPL(hv_remove_crash_handler);
+
+void __weak hyperv_cleanup(void)
+{
+}
+EXPORT_SYMBOL_GPL(hyperv_cleanup);
diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
index f5fd88eedaed..f34a7f7be4e9 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h
@@ -231,6 +231,7 @@ static inline int cpumask_to_vpset(struct hv_vpset *vpset,
 void hyperv_report_panic(struct pt_regs *regs, long err, bool in_die);
 bool hv_is_hyperv_initialized(void);
 bool hv_is_hibernation_supported(void);
+bool hv_is_isolation_supported(void);
 void hyperv_cleanup(void);
 bool hv_query_ext_cap(u64 cap_query);
 #else /* CONFIG_HYPERV */
-- 
2.33.1