On Mon, Jun 18, 2012 at 9:32 AM, Avi Kivity <a...@redhat.com> wrote:
> On 06/15/2012 10:08 PM, Christoffer Dall wrote:
>> From: Christoffer Dall <cd...@cs.columbia.edu>
>>
>> Userspace can inject IRQs and FIQs through the KVM_IRQ_LINE VM ioctl.
>> This ioctl is used since the sematics are in fact two lines that can be
>> either raised or lowered on the VCPU - the IRQ and FIQ lines.
>>
>> KVM needs to know which VCPU it must operate on and whether the FIQ or
>> IRQ line is raised/lowered. Hence both pieces of information is packed
>> in the kvm_irq_level->irq field. The irq fild value will be:
>> IRQ: vcpu_index << 1
>> FIQ: (vcpu_index << 1) | 1
>>
>> This is documented in Documentation/kvm/api.txt.
>>
>> The effect of the ioctl is simply to simply raise/lower the
>> corresponding irq_line field on the VCPU struct, which will cause the
>> world-switch code to raise/lower virtual interrupts when running the
>> guest on next switch. The wait_for_interrupt flag is also cleared for
>> raised IRQs or FIQs causing an idle VCPU to become active again. CPUs
>> in guest mode are kicked to make sure they refresh their interrupt status.
>
>>
>> +static int kvm_arch_vm_ioctl_irq_line(struct kvm *kvm,
>> + struct kvm_irq_level *irq_level)
>> +{
>> + int mask;
>> + unsigned int vcpu_idx;
>> + struct kvm_vcpu *vcpu;
>> + unsigned long old, new, *ptr;
>> +
>> + vcpu_idx = irq_level->irq >> 1;
>> + if (vcpu_idx >= KVM_MAX_VCPUS)
>> + return -EINVAL;
>> +
>> + vcpu = kvm_get_vcpu(kvm, vcpu_idx);
>> + if (!vcpu)
>> + return -EINVAL;
>> +
>> + if ((irq_level->irq & 1) == KVM_ARM_IRQ_LINE)
>> + mask = HCR_VI;
>> + else /* KVM_ARM_FIQ_LINE */
>> + mask = HCR_VF;
>> +
>> + trace_kvm_set_irq(irq_level->irq, irq_level->level, 0);
>> +
>> + ptr = (unsigned long *)&vcpu->arch.irq_lines;
>> + do {
>> + old = ACCESS_ONCE(*ptr);
>> + if (irq_level->level)
>> + new = old | mask;
>> + else
>> + new = old & ~mask;
>> +
>> + if (new == old)
>> + return 0; /* no change */
>> + } while (cmpxchg(ptr, old, new) != old);
>
> Isn't this a complicated
>
>
> if (level)
> set_bit()
> else
> clear_bit()
>
> ?
>
we need to atomically know if we changed either the FIQ/IRQ fields and
atomically update without locking. (I think you suggested this
approach, in fact).
>> +
>> + /*
>> + * The vcpu irq_lines field was updated, wake up sleeping VCPUs and
>> + * trigger a world-switch round on the running physical CPU to set the
>> + * virtual IRQ/FIQ fields in the HCR appropriately.
>> + */
>> + kvm_vcpu_kick(vcpu);
>
> No need to wake when the line is asserted so you can make this
> conditional on level.
>
we need to trigger a world switch to update the virtualized register
from the actual running physical CPU if we changed any of the IRQ/FIQ
fields. We return in the loop above if we didn't change anything.
>> +
>> + return 0;
>> +}
>> +
>> long kvm_arch_vcpu_ioctl(struct file *filp,
>> unsigned int ioctl, unsigned long arg)
>> {
>> @@ -298,7 +345,20 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct
>> kvm_dirty_log *log)
>> long kvm_arch_vm_ioctl(struct file *filp,
>> unsigned int ioctl, unsigned long arg)
>> {
>> - return -EINVAL;
>> + struct kvm *kvm = filp->private_data;
>> + void __user *argp = (void __user *)arg;
>> +
>> + switch (ioctl) {
>> + case KVM_IRQ_LINE: {
>> + struct kvm_irq_level irq_event;
>> +
>> + if (copy_from_user(&irq_event, argp, sizeof irq_event))
>> + return -EFAULT;
>> + return kvm_arch_vm_ioctl_irq_line(kvm, &irq_event);
>> + }
>> + default:
>> + return -EINVAL;
>> + }
>> }
>
> Should be in common code guarded by the define introduced previously.
>
>
you mean like this: ?
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index a9f209b..5bf2193 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -535,8 +535,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu,
struct kvm_run *run)
return ret;
}
-static int kvm_arch_vm_ioctl_irq_line(struct kvm *kvm,
- struct kvm_irq_level *irq_level)
+int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_level)
{
int mask;
unsigned int vcpu_idx;
@@ -596,20 +595,7 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
struct kvm_dirty_log *log)
long kvm_arch_vm_ioctl(struct file *filp,
unsigned int ioctl, unsigned long arg)
{
- struct kvm *kvm = filp->private_data;
- void __user *argp = (void __user *)arg;
-
- switch (ioctl) {
- case KVM_IRQ_LINE: {
- struct kvm_irq_level irq_event;
-
- if (copy_from_user(&irq_event, argp, sizeof irq_event))
- return -EFAULT;
- return kvm_arch_vm_ioctl_irq_line(kvm, &irq_event);
- }
- default:
- return -EINVAL;
- }
+ return -EINVAL;
}
static void cpu_set_vector(void *vector)
diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c
index bd77cb5..122a4b2 100644
--- a/arch/ia64/kvm/kvm-ia64.c
+++ b/arch/ia64/kvm/kvm-ia64.c
@@ -924,6 +924,16 @@ int kvm_arch_vcpu_ioctl_set_regs(struct kvm_vcpu
*vcpu, struct kvm_regs *regs)
return 0;
}
+int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_event)
+{
+ if (!irqchip_in_kernel(kvm))
+ return -ENXIO;
+
+ irq_event->statusstatus = kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID,
+ irq_event->irq, irq_event->level);
+ return 0;
+}
+
long kvm_arch_vm_ioctl(struct file *filp,
unsigned int ioctl, unsigned long arg)
{
@@ -963,29 +973,6 @@ long kvm_arch_vm_ioctl(struct file *filp,
goto out;
}
break;
- case KVM_IRQ_LINE_STATUS:
- case KVM_IRQ_LINE: {
- struct kvm_irq_level irq_event;
-
- r = -EFAULT;
- if (copy_from_user(&irq_event, argp, sizeof irq_event))
- goto out;
- r = -ENXIO;
- if (irqchip_in_kernel(kvm)) {
- __s32 status;
- status = kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID,
- irq_event.irq, irq_event.level);
- if (ioctl == KVM_IRQ_LINE_STATUS) {
- r = -EFAULT;
- irq_event.status = status;
- if (copy_to_user(argp, &irq_event,
- sizeof irq_event))
- goto out;
- }
- r = 0;
- }
- break;
- }
case KVM_GET_IRQCHIP: {
/* 0: PIC master, 1: PIC slave, 2: IOAPIC */
struct kvm_irqchip chip;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index a01a424..c9c4186 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3144,6 +3144,16 @@ out:
return r;
}
+int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_event)
+{
+ if (!irqchip_in_kernel(kvm))
+ return -ENXIO;
+
+ irq_event->status = kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID,
+ irq_event->irq, irq_event->level);
+ return 0;
+}
+
long kvm_arch_vm_ioctl(struct file *filp,
unsigned int ioctl, unsigned long arg)
{
@@ -3250,29 +3260,6 @@ long kvm_arch_vm_ioctl(struct file *filp,
create_pit_unlock:
mutex_unlock(&kvm->slots_lock);
break;
- case KVM_IRQ_LINE_STATUS:
- case KVM_IRQ_LINE: {
- struct kvm_irq_level irq_event;
-
- r = -EFAULT;
- if (copy_from_user(&irq_event, argp, sizeof irq_event))
- goto out;
- r = -ENXIO;
- if (irqchip_in_kernel(kvm)) {
- __s32 status;
- status = kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID,
- irq_event.irq, irq_event.level);
- if (ioctl == KVM_IRQ_LINE_STATUS) {
- r = -EFAULT;
- irq_event.status = status;
- if (copy_to_user(argp, &irq_event,
- sizeof irq_event))
- goto out;
- }
- r = 0;
- }
- break;
- }
case KVM_GET_IRQCHIP: {
/* 0: PIC master, 1: PIC slave, 2: IOAPIC */
struct kvm_irqchip *chip;
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index e3c86f8..96aa7fb 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -494,6 +494,7 @@ int kvm_vm_ioctl_set_memory_region(struct kvm *kvm,
struct
kvm_userspace_memory_region *mem,
int user_alloc);
+int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_level);
long kvm_arch_vm_ioctl(struct file *filp,
unsigned int ioctl, unsigned long arg);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 636bd08..1d33877 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2093,6 +2093,25 @@ static long kvm_vm_ioctl(struct file *filp,
break;
}
#endif
+#ifdef __KVM_HAVE_IRQ_LINE
+ case KVM_IRQ_LINE_STATUS:
+ case KVM_IRQ_LINE: {
+ struct kvm_irq_level irq_event;
+
+ r = -EFAULT;
+ if (copy_from_user(&irq_event, argp, sizeof irq_event))
+ goto out;
+
+ r = kvm_vm_ioctl_irq_line(kvm, &irq_event);
+
+ if (ioctl == KVM_IRQ_LINE_STATUS) {
+ if (copy_to_user(argp, &irq_event, sizeof irq_event))
+ r = -EFAULT;
+ }
+
+ break;
+ }
+#endif
default:
r = kvm_arch_vm_ioctl(filp, ioctl, arg);
if (r == -ENOTTY)
---
Thanks,
Christoffer
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