Re: [Xen-devel] [PATCH 7/7] xen: Enable event channel of PV extensionof HVM
From: Jeremy Fitzhardinge
Date: Mon Mar 08 2010 - 17:16:42 EST
On 03/04/2010 10:07 PM, Sheng Yang wrote:
We mapped each IOAPIC pin to a VIRQ, so that we can deliver interrupt through
these VIRQs.
We used X86_PLATFORM_IPI_VECTOR as the notification vector for hypervisor
to notify guest about the event.
The patch also enabled SMP support, then we can support IPI through evtchn as well.
When this feature is enabled, we would relay on Xen PV timer for clockevent,
rather than other hardware emulated ones.
Then we don't use IOAPIC/LAPIC, eliminated the overhead brought by
unnecessary VMExit caused by LAPIC.
Signed-off-by: Sheng Yang<sheng@xxxxxxxxxxxxxxx>
---
arch/x86/xen/enlighten.c | 6 ++--
arch/x86/xen/hvmpv.c | 59 +++++++++++++++++++++++++++++++++
arch/x86/xen/irq.c | 28 ++++++++++++++++
arch/x86/xen/smp.c | 76 ++++++++++++++++++++++++++++++++++++++++--
arch/x86/xen/xen-ops.h | 16 +++++++++
drivers/xen/events.c | 74 ++++++++++++++++++++++++++++++++++++++---
include/xen/events.h | 4 ++
include/xen/hvm.h | 5 +++
include/xen/interface/xen.h | 6 +++-
9 files changed, 260 insertions(+), 14 deletions(-)
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 36daccb..2d60e70 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -717,7 +717,7 @@ static u32 xen_safe_apic_wait_icr_idle(void)
return 0;
}
-static void set_xen_basic_apic_ops(void)
+void xen_set_basic_apic_ops(void)
{
apic->read = xen_apic_read;
apic->write = xen_apic_write;
@@ -1026,7 +1026,7 @@ static void xen_crash_shutdown(struct pt_regs *regs)
xen_reboot(SHUTDOWN_crash);
}
-static const struct machine_ops __initdata xen_machine_ops = {
+const struct machine_ops __initdata xen_machine_ops = {
.restart = xen_restart,
.halt = xen_machine_halt,
.power_off = xen_machine_halt,
@@ -1116,7 +1116,7 @@ asmlinkage void __init xen_start_kernel(void)
/*
* set up the basic apic ops.
*/
- set_xen_basic_apic_ops();
+ xen_set_basic_apic_ops();
#endif
if (xen_feature(XENFEAT_mmu_pt_update_preserve_ad)) {
diff --git a/arch/x86/xen/hvmpv.c b/arch/x86/xen/hvmpv.c
index 305dcca..673b036 100644
--- a/arch/x86/xen/hvmpv.c
+++ b/arch/x86/xen/hvmpv.c
@@ -17,6 +17,7 @@
#include<xen/interface/version.h>
#include<xen/interface/memory.h>
+#include<asm/reboot.h>
#include<asm/xen/cpuid.h>
#include<asm/xen/hypercall.h>
#include<asm/xen/hypervisor.h>
@@ -44,6 +45,8 @@ static void __init xen_hvm_pv_banner(void)
printk(KERN_INFO "Xen version: %d.%d%s\n",
version>> 16, version& 0xffff, extra.extraversion);
printk(KERN_INFO "PV feature: PV clocksource enabled\n");
+ if (xen_hvm_pv_evtchn_enabled())
+ printk(KERN_INFO "PV feature: Event channel enabled\n");
}
static int __init xen_para_available(void)
@@ -83,6 +86,9 @@ static int __init init_hvm_pv_info(void)
if (!(edx& XEN_CPUID_FEAT2_HVM_PV))
return -ENODEV;
+ if (edx& XEN_CPUID_FEAT2_HVM_PV_EVTCHN)
+ xen_hvm_pv_features |= XEN_HVM_PV_EVTCHN_ENABLED;
+
if (pages< 1)
return -ENODEV;
@@ -127,9 +133,35 @@ static void __init init_pv_clocksource(void)
xen_register_clocksource();
}
+static int set_callback_via(uint64_t via)
+{
+ struct xen_hvm_param a;
+
+ a.domid = DOMID_SELF;
+ a.index = HVM_PARAM_CALLBACK_IRQ;
+ a.value = via;
+ return HYPERVISOR_hvm_op(HVMOP_set_param,&a);
+}
+
+void do_hvm_pv_evtchn_intr(void)
+{
+ per_cpu(irq_count, smp_processor_id())++;
+ xen_hvm_evtchn_do_upcall(get_irq_regs());
+ per_cpu(irq_count, smp_processor_id())--;
+}
+
+#ifdef CONFIG_X86_LOCAL_APIC
+static void xen_hvm_pv_evtchn_apic_write(u32 reg, u32 val)
+{
+ /* The only one reached here should be EOI */
+ WARN_ON(reg != APIC_EOI);
+}
+#endif
+
void __init xen_guest_init(void)
{
int r;
+ uint64_t callback_via;
/* Ensure the we won't confused with others */
if (xen_domain())
@@ -152,4 +184,31 @@ void __init xen_guest_init(void)
init_pv_clocksource();
xen_domain_type = XEN_HVM_DOMAIN;
+
+ if (xen_hvm_pv_evtchn_enabled()) {
+ xen_hvm_pv_init_irq_ops();
+
+ x86_init.timers.timer_init = xen_time_init;
+ x86_init.timers.setup_percpu_clockev = x86_init_noop;
+ x86_cpuinit.setup_percpu_clockev = x86_init_noop;
+
+ pv_apic_ops.startup_ipi_hook = paravirt_nop;
+#ifdef CONFIG_X86_LOCAL_APIC
+ /*
+ * set up the basic apic ops.
+ */
+ xen_set_basic_apic_ops();
+ apic->write = xen_hvm_pv_evtchn_apic_write;
+#endif
+
+ callback_via = HVM_CALLBACK_VECTOR(X86_PLATFORM_IPI_VECTOR);
+ set_callback_via(callback_via);
+
+ x86_platform_ipi_callback = do_hvm_pv_evtchn_intr;
+
+ disable_acpi();
+
+ xen_hvm_pv_smp_init();
+ machine_ops = xen_machine_ops;
+ }
}
diff --git a/arch/x86/xen/irq.c b/arch/x86/xen/irq.c
index 9d30105..e325640 100644
--- a/arch/x86/xen/irq.c
+++ b/arch/x86/xen/irq.c
@@ -2,6 +2,7 @@
#include<asm/x86_init.h>
+#include<xen/xen.h>
#include<xen/interface/xen.h>
#include<xen/interface/sched.h>
#include<xen/interface/vcpu.h>
@@ -131,3 +132,30 @@ void __init xen_init_irq_ops()
pv_irq_ops = xen_irq_ops;
x86_init.irqs.intr_init = xen_init_IRQ;
}
+
+#ifdef CONFIG_XEN_HVM_PV
+static void xen_hvm_pv_evtchn_disable(void)
+{
+ native_irq_disable();
+ xen_irq_disable();
+}
+PV_CALLEE_SAVE_REGS_THUNK(xen_hvm_pv_evtchn_disable);
+
+static void xen_hvm_pv_evtchn_enable(void)
+{
+ native_irq_enable();
+ xen_irq_enable();
+}
Why is it necessary to disable both the event mask and eflags.IF?
Surely IF is enough?
If it is necessary here, why not for save/restore flags?
J
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