On 4/27/2026 11:08 AM, Michael Kelley wrote:
From: Naman Jain <[email protected]> Sent: Thursday, April 23, 2026
5:42 AM
Move the vmbus_handler global variable and hv_setup_vmbus_handler()/
hv_remove_vmbus_handler() from arch/x86 to drivers/hv/hv_common.c.
hv_setup_vmbus_handler() is called unconditionally in vmbus_bus_init()
and works for both x86 (sysvec handler) and arm64 (vmbus_percpu_isr).
This eliminates the need for separate percpu vmbus handler setup
functions and __weak stubs, that are needed for adding ARM64 support
in MSHV_VTL driver where we need to set a custom per-cpu vmbus handler.
Signed-off-by: Naman Jain <[email protected]>
---
arch/x86/kernel/cpu/mshyperv.c | 12 ------------
drivers/hv/hv_common.c | 9 +++++++--
drivers/hv/vmbus_drv.c | 17 +++++++++--------
include/asm-generic/mshyperv.h | 1 +
4 files changed, 17 insertions(+), 22 deletions(-)
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 89a2eb8a0722..68706ff5880e 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -145,7 +145,6 @@ void hv_set_msr(unsigned int reg, u64 value)
EXPORT_SYMBOL_GPL(hv_set_msr);
static void (*mshv_handler)(void);
-static void (*vmbus_handler)(void);
static void (*hv_stimer0_handler)(void);
static void (*hv_kexec_handler)(void);
static void (*hv_crash_handler)(struct pt_regs *regs);
@@ -172,17 +171,6 @@ void hv_setup_mshv_handler(void (*handler)(void))
mshv_handler = handler;
}
-void hv_setup_vmbus_handler(void (*handler)(void))
-{
- vmbus_handler = handler;
-}
-
-void hv_remove_vmbus_handler(void)
-{
- /* We have no way to deallocate the interrupt gate */
- vmbus_handler = NULL;
-}
-
/*
* Routines to do per-architecture handling of stimer0
* interrupts when in Direct Mode
diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
index e8633bc51d56..eb7b0028b45d 100644
--- a/drivers/hv/hv_common.c
+++ b/drivers/hv/hv_common.c
@@ -758,13 +758,18 @@ bool __weak hv_isolation_type_tdx(void)
}
EXPORT_SYMBOL_GPL(hv_isolation_type_tdx);
-void __weak hv_setup_vmbus_handler(void (*handler)(void))
+void (*vmbus_handler)(void);
+EXPORT_SYMBOL_GPL(vmbus_handler);
+
+void hv_setup_vmbus_handler(void (*handler)(void))
{
+ vmbus_handler = handler;
}
EXPORT_SYMBOL_GPL(hv_setup_vmbus_handler);
-void __weak hv_remove_vmbus_handler(void)
+void hv_remove_vmbus_handler(void)
{
+ vmbus_handler = NULL;
}
EXPORT_SYMBOL_GPL(hv_remove_vmbus_handler);
I'd suggest moving hv_setup_vmbus_handler() and
hv_remove_vmbus_handler() above or below the group
of __weak stubs in this source code file. There's a comment
describing the purpose of these __weak functions, and
intermixing these two functions that are no longer __weak
produces something of a jumble.
Acked.
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index bc4fc1951ae1..052ca8b11cee 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -1415,7 +1415,8 @@ EXPORT_SYMBOL_FOR_MODULES(vmbus_isr, "mshv_vtl");
static irqreturn_t vmbus_percpu_isr(int irq, void *dev_id)
{
- vmbus_isr();
+ if (vmbus_handler)
+ vmbus_handler();
Is it necessary to test vmbus_handler first? From what I can
see, it is always set before the per-cpu interrupt is setup.
After the shuffle of hv_remove_vmbus_handler() and freeing the irq, it
can be safely removed. When I was setting the vmbus_handler to NULL
first, before freeing the IRQ, this was required.
return IRQ_HANDLED;
}
@@ -1517,8 +1518,10 @@ static int vmbus_bus_init(void)
vmbus_irq_initialized = true;
}
+ hv_setup_vmbus_handler(vmbus_isr);
+
if (vmbus_irq == -1) {
- hv_setup_vmbus_handler(vmbus_isr);
+ /* x86: sysvec handler uses vmbus_handler directly */
} else {
ret = request_percpu_irq(vmbus_irq, vmbus_percpu_isr,
"Hyper-V VMbus", &vmbus_evt);
@@ -1553,9 +1556,8 @@ static int vmbus_bus_init(void)
return 0;
err_connect:
- if (vmbus_irq == -1)
- hv_remove_vmbus_handler();
- else
+ hv_remove_vmbus_handler();
+ if (vmbus_irq != -1)
free_percpu_irq(vmbus_irq, &vmbus_evt);
These operations should be reordered so they are the inverse
of how they are setup. I.e., free_percpu_irq() first, then remove
the VMBus handler. That's just good standard practice unless
there's a specific reason to do the cleanup ordering differently. In
fact, hv_remove_vmbus_handler() needs to be moved down
to the err_setup label so it's done if request_percpu_irq()
fails.
Acked. I will do the same for other hv_remove_vmbus_handler() as well.
err_setup:
if (IS_ENABLED(CONFIG_PREEMPT_RT) && vmbus_irq_initialized) {
@@ -3026,9 +3028,8 @@ static void __exit vmbus_exit(void)
vmbus_connection.conn_state = DISCONNECTED;
hv_stimer_global_cleanup();
vmbus_disconnect();
- if (vmbus_irq == -1)
- hv_remove_vmbus_handler();
- else
+ hv_remove_vmbus_handler();
+ if (vmbus_irq != -1)
free_percpu_irq(vmbus_irq, &vmbus_evt);
Ordering should be changed here as well so it is the inverse
of how things are set up.
if (IS_ENABLED(CONFIG_PREEMPT_RT) && vmbus_irq_initialized) {
smpboot_unregister_percpu_thread(&vmbus_irq_threads);
diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
index 2810aa05dc73..db183c8cfb95 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h
@@ -179,6 +179,7 @@ static inline u64 hv_generate_guest_id(u64 kernel_version)
int hv_get_hypervisor_version(union hv_hypervisor_version_info *info);
+extern void (*vmbus_handler)(void);
void hv_setup_vmbus_handler(void (*handler)(void));
void hv_remove_vmbus_handler(void);
void hv_setup_stimer0_handler(void (*handler)(void));
--
2.43.0
Regards,
Naman
