From: Naman Jain <[email protected]> Sent: Monday, March 16, 2026 5:13 AM > > Add a wrapper function - hv_setup_percpu_vmbus_handler(), similar to > hv_setup_vmbus_handler() to allow setting up custom per-cpu VMBus > interrupt handler. This is required for arm64 support, to be added > in MSHV_VTL driver, where per-cpu VMBus interrupt handler will be > set to mshv_vtl_vmbus_isr() for VTL2 (Virtual Trust Level 2).
Needing both hv_setup_vmbus_handler() and hv_setup_percpu_vmbus_handler() seems unfortunate. Here's an alternate approach to consider: 1. I think the x86 VMBus sysvec handler and the vmbus_percpu_isr() functions could both use the same vmbus_handler global variable. Looking at your changes in this patch set, hv_setup_vmbus_handler() and hv_setup_percpu_vmbus_handler() are used together and always set the same value. 2. So move the global variable vmbus_handler out from arch/x86 and into hv_common.c, and export it. The x86 sysvec handler can still reference it, and vmbus_percpu_isr() in vmbus_drv.c can also reference it. No need to have vmbus_percpu_isr() under arch/arm64 or have a stub in hv_common.c. 3. hv_setup_vmbus_handler() and hv_remove_vmbus_handler() also move to hv_common.c. The __weak stubs go away. With these changes, only hv_setup_vmbus_handler() needs to be called, and it works for both x86 with the sysvec handler and for arm64 with vmbus_percpu_isr(). I haven't coded this up, so maybe there's some problematic detail, but the idea seems like it would work. If it does work, some of my comments below are no longer applicable. > > Signed-off-by: Saurabh Sengar <[email protected]> > Signed-off-by: Naman Jain <[email protected]> > --- > arch/arm64/hyperv/mshyperv.c | 13 +++++++++++++ > drivers/hv/hv_common.c | 11 +++++++++++ > drivers/hv/vmbus_drv.c | 7 +------ > include/asm-generic/mshyperv.h | 3 +++ > 4 files changed, 28 insertions(+), 6 deletions(-) > > diff --git a/arch/arm64/hyperv/mshyperv.c b/arch/arm64/hyperv/mshyperv.c > index 4fdc26ade1d7..d4494ceeaad0 100644 > --- a/arch/arm64/hyperv/mshyperv.c > +++ b/arch/arm64/hyperv/mshyperv.c > @@ -134,3 +134,16 @@ bool hv_is_hyperv_initialized(void) > return hyperv_initialized; > } > EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized); > + > +static void (*vmbus_percpu_handler)(void); > +void hv_setup_percpu_vmbus_handler(void (*handler)(void)) > +{ > + vmbus_percpu_handler = handler; > +} > + > +irqreturn_t vmbus_percpu_isr(int irq, void *dev_id) > +{ > + if (vmbus_percpu_handler) > + vmbus_percpu_handler(); > + return IRQ_HANDLED; > +} > diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c > index d1ebc0ebd08f..a5064f558bf6 100644 > --- a/drivers/hv/hv_common.c > +++ b/drivers/hv/hv_common.c > @@ -759,6 +759,17 @@ void __weak hv_setup_vmbus_handler(void (*handler)(void)) > } > EXPORT_SYMBOL_GPL(hv_setup_vmbus_handler); > > +irqreturn_t __weak vmbus_percpu_isr(int irq, void *dev_id) > +{ > + return IRQ_HANDLED; > +} > +EXPORT_SYMBOL_GPL(vmbus_percpu_isr); > + > +void __weak hv_setup_percpu_vmbus_handler(void (*handler)(void)) > +{ > +} > +EXPORT_SYMBOL_GPL(hv_setup_percpu_vmbus_handler); You've implemented hv_setup_percpu_vmbus_handler() following the pattern of hv_setup_vmbus_handler(), which is reasonable. But that turns out to be unnecessarily complicated. The existing hv_setup_vmbus_handler() has a portion in arch/x86/kernel/cpu/mshyperv.c as a special case because it uses a hard-coded interrupt vector on x86/x64, and has its own custom sysvec code. And there's a need for a __weak stub in hv_common.c so that vmbus_drv.c will compile on arm64. But hv_setup_percpu_vmbus_handler() does not have the same requirements. It could be implemented entirely in vmbus_drv.c, with no code under arch/x86 or arch/arm64, and no __weak stub in hv_common.c. vmbus_drv.c would just need to EXPORT_SYMBOL_FOR_MODULES, like it already does with vmbus_isr. I didn't code it up, but I think that approach would be simpler with fewer piece-parts scattered all over. If so, it would be worth breaking the symmetry with hv_setup_vmbus_handler(). > + > void __weak hv_remove_vmbus_handler(void) > { > } > diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c > index bc4fc1951ae1..f99d4f2d3862 100644 > --- a/drivers/hv/vmbus_drv.c > +++ b/drivers/hv/vmbus_drv.c > @@ -1413,12 +1413,6 @@ void vmbus_isr(void) > } > EXPORT_SYMBOL_FOR_MODULES(vmbus_isr, "mshv_vtl"); > > -static irqreturn_t vmbus_percpu_isr(int irq, void *dev_id) > -{ > - vmbus_isr(); > - return IRQ_HANDLED; > -} > - > static void vmbus_percpu_work(struct work_struct *work) > { > unsigned int cpu = smp_processor_id(); > @@ -1520,6 +1514,7 @@ static int vmbus_bus_init(void) > if (vmbus_irq == -1) { > hv_setup_vmbus_handler(vmbus_isr); > } else { > + hv_setup_percpu_vmbus_handler(vmbus_isr); > ret = request_percpu_irq(vmbus_irq, vmbus_percpu_isr, > "Hyper-V VMbus", &vmbus_evt); > if (ret) { > diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h > index 108f135d4fd9..b147a12085e4 100644 > --- a/include/asm-generic/mshyperv.h > +++ b/include/asm-generic/mshyperv.h > @@ -22,6 +22,7 @@ > #include <linux/bitops.h> > #include <acpi/acpi_numa.h> > #include <linux/cpumask.h> > +#include <linux/interrupt.h> > #include <linux/nmi.h> > #include <asm/ptrace.h> > #include <hyperv/hvhdk.h> > @@ -179,6 +180,8 @@ static inline u64 hv_generate_guest_id(u64 kernel_version) > > int hv_get_hypervisor_version(union hv_hypervisor_version_info *info); > > +irqreturn_t vmbus_percpu_isr(int irq, void *dev_id); > +void hv_setup_percpu_vmbus_handler(void (*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 >
