VMbus interrupts are most naturally modelled as per-cpu IRQs. But
because x86/x64 doesn't have per-cpu IRQs, the core VMbus interrupt
handling machinery is done in code under arch/x86 and Linux IRQs are
not used. Adding support for ARM64 means adding equivalent code
using per-cpu IRQs under arch/arm64.
A better model is to treat per-cpu IRQs as the normal path (which it is
for modern architectures), and the x86/x64 path as the exception. Do this
by incorporating standard Linux per-cpu IRQ allocation into the main VMbus
driver, and bypassing it in the x86/x64 exception case. For x86/x64,
special case code is retained under arch/x86, but no VMbus interrupt
handling code is needed under arch/arm64.
No functional change.
Signed-off-by: Michael Kelley <mikel...@microsoft.com>
Reviewed-by: Boqun Feng <boqun.f...@gmail.com>
---
arch/x86/include/asm/mshyperv.h | 1 -
arch/x86/kernel/cpu/mshyperv.c | 13 +++------
drivers/hv/hv.c | 8 +++++-
drivers/hv/vmbus_drv.c | 63 ++++++++++++++++++++++++++++++++++++-----
include/asm-generic/mshyperv.h | 7 ++---
5 files changed, 70 insertions(+), 22 deletions(-)
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index a6c608d..c10dd1c 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -32,7 +32,6 @@ static inline u64 hv_get_register(unsigned int reg)
#define hv_enable_vdso_clocksource() \
vclocks_set_used(VDSO_CLOCKMODE_HVCLOCK);
#define hv_get_raw_timer() rdtsc_ordered()
-#define hv_get_vector() HYPERVISOR_CALLBACK_VECTOR
/*
* Reference to pv_ops must be inline so objtool
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index e88bc29..41fd84a 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -60,23 +60,18 @@
set_irq_regs(old_regs);
}
-int hv_setup_vmbus_irq(int irq, void (*handler)(void))
+void hv_setup_vmbus_handler(void (*handler)(void))
{
- /*
- * The 'irq' argument is ignored on x86/x64 because a hard-coded
- * interrupt vector is used for Hyper-V interrupts.
- */
vmbus_handler = handler;
- return 0;
}
+EXPORT_SYMBOL_GPL(hv_setup_vmbus_handler);
-void hv_remove_vmbus_irq(void)
+void hv_remove_vmbus_handler(void)
{
/* We have no way to deallocate the interrupt gate */
vmbus_handler = NULL;
}
-EXPORT_SYMBOL_GPL(hv_setup_vmbus_irq);
-EXPORT_SYMBOL_GPL(hv_remove_vmbus_irq);
+EXPORT_SYMBOL_GPL(hv_remove_vmbus_handler);
/*
* Routines to do per-architecture handling of stimer0
diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
index afe7a62..917b29e 100644
--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -16,6 +16,7 @@
#include <linux/version.h>
#include <linux/random.h>
#include <linux/clockchips.h>
+#include <linux/interrupt.h>
#include <clocksource/hyperv_timer.h>
#include <asm/mshyperv.h>
#include "hyperv_vmbus.h"
@@ -214,10 +215,12 @@ void hv_synic_enable_regs(unsigned int cpu)
hv_set_register(HV_REGISTER_SIEFP, siefp.as_uint64);
/* Setup the shared SINT. */
+ if (vmbus_irq != -1)
+ enable_percpu_irq(vmbus_irq, 0);
shared_sint.as_uint64 = hv_get_register(HV_REGISTER_SINT0 +
VMBUS_MESSAGE_SINT);
- shared_sint.vector = hv_get_vector();
+ shared_sint.vector = vmbus_interrupt;
shared_sint.masked = false;
/*
@@ -285,6 +288,9 @@ void hv_synic_disable_regs(unsigned int cpu)
sctrl.as_uint64 = hv_get_register(HV_REGISTER_SCONTROL);
sctrl.enable = 0;
hv_set_register(HV_REGISTER_SCONTROL, sctrl.as_uint64);
+
+ if (vmbus_irq != -1)
+ disable_percpu_irq(vmbus_irq);
}
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 7524d71..51c40d5 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -48,8 +48,10 @@ struct vmbus_dynid {
static void *hv_panic_page;
+static long __percpu *vmbus_evt;
+
/* Values parsed from ACPI DSDT */
-static int vmbus_irq;
+int vmbus_irq;
int vmbus_interrupt;
/*
@@ -1381,7 +1383,13 @@ static void vmbus_isr(void)
tasklet_schedule(&hv_cpu->msg_dpc);
}
- add_interrupt_randomness(hv_get_vector(), 0);
+ add_interrupt_randomness(vmbus_interrupt, 0);
+}
+
+static irqreturn_t vmbus_percpu_isr(int irq, void *dev_id)
+{
+ vmbus_isr();
+ return IRQ_HANDLED;
}
/*
@@ -1496,9 +1504,28 @@ static int vmbus_bus_init(void)
if (ret)
return ret;
- ret = hv_setup_vmbus_irq(vmbus_irq, vmbus_isr);
- if (ret)
- goto err_setup;
+ /*
+ * VMbus interrupts are best modeled as per-cpu interrupts. If
+ * on an architecture with support for per-cpu IRQs (e.g. ARM64),
+ * allocate a per-cpu IRQ using standard Linux kernel functionality.
+ * If not on such an architecture (e.g., x86/x64), then rely on
+ * code in the arch-specific portion of the code tree to connect
+ * the VMbus interrupt handler.
+ */
+
+ if (vmbus_irq == -1) {
+ hv_setup_vmbus_handler(vmbus_isr);
+ } else {
+ vmbus_evt = alloc_percpu(long);
+ ret = request_percpu_irq(vmbus_irq, vmbus_percpu_isr,
+ "Hyper-V VMbus", vmbus_evt);
+ if (ret) {
+ pr_err("Can't request Hyper-V VMbus IRQ %d, Err %d",
+ vmbus_irq, ret);
+ free_percpu(vmbus_evt);
+ goto err_setup;
+ }
+ }
ret = hv_synic_alloc();
if (ret)
@@ -1559,7 +1586,12 @@ static int vmbus_bus_init(void)
err_cpuhp:
hv_synic_free();
err_alloc:
- hv_remove_vmbus_irq();
+ if (vmbus_irq == -1) {
+ hv_remove_vmbus_handler();
+ } else {
+ free_percpu_irq(vmbus_irq, vmbus_evt);
+ free_percpu(vmbus_evt);
+ }
err_setup:
bus_unregister(&hv_bus);
unregister_sysctl_table(hv_ctl_table_hdr);
@@ -2677,6 +2709,18 @@ static int __init hv_acpi_init(void)
ret = -ETIMEDOUT;
goto cleanup;
}
+
+ /*
+ * If we're on an architecture with a hardcoded hypervisor
+ * vector (i.e. x86/x64), override the VMbus interrupt found
+ * in the ACPI tables. Ensure vmbus_irq is not set since the
+ * normal Linux IRQ mechanism is not used in this case.
+ */
+#ifdef HYPERVISOR_CALLBACK_VECTOR
+ vmbus_interrupt = HYPERVISOR_CALLBACK_VECTOR;
+ vmbus_irq = -1;
+#endif
+
hv_debug_init();
ret = vmbus_bus_init();
@@ -2707,7 +2751,12 @@ static void __exit vmbus_exit(void)
vmbus_connection.conn_state = DISCONNECTED;
hv_stimer_global_cleanup();
vmbus_disconnect();
- hv_remove_vmbus_irq();
+ if (vmbus_irq == -1) {
+ hv_remove_vmbus_handler();
+ } else {
+ free_percpu_irq(vmbus_irq, vmbus_evt);
+ free_percpu(vmbus_evt);
+ }
for_each_online_cpu(cpu) {
struct hv_per_cpu_context *hv_cpu
= per_cpu_ptr(hv_context.cpu_context, cpu);
diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
index 70b798d..43dc371 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h
@@ -92,10 +92,8 @@ static inline void vmbus_signal_eom(struct hv_message *msg,
u32 old_msg_type)
}
}
-int hv_setup_vmbus_irq(int irq, void (*handler)(void));
-void hv_remove_vmbus_irq(void);
-void hv_enable_vmbus_irq(void);
-void hv_disable_vmbus_irq(void);
+void hv_setup_vmbus_handler(void (*handler)(void));
+void hv_remove_vmbus_handler(void);
void hv_setup_kexec_handler(void (*handler)(void));
void hv_remove_kexec_handler(void);
@@ -103,6 +101,7 @@ static inline void vmbus_signal_eom(struct hv_message *msg,
u32 old_msg_type)
void hv_remove_crash_handler(void);
extern int vmbus_interrupt;
+extern int vmbus_irq;
#if IS_ENABLED(CONFIG_HYPERV)
/*
--
1.8.3.1
