[PATCH 17/41] KVM: Add guest mode signal mask

Avi Kivity
2007-04-01T14:35:14Z

Allow a special signal mask to be used while executing in guest mode. This
allows signals to be used to interrupt a vcpu without requiring signal
delivery to a userspace handler, which is quite expensive. Userspace still
receives -EINTR and can get the signal via sigwait().

Signed-off-by: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
---
drivers/kvm/kvm.h | 3 +++
drivers/kvm/kvm_main.c | 41 +++++++++++++++++++++++++++++++++++++++++
include/linux/kvm.h | 7 +++++++
3 files changed, 51 insertions(+), 0 deletions(-)

diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index be3a0e7..1c4a581 100644
--- a/drivers/kvm/kvm.h
+++ b/drivers/kvm/kvm.h
@@ -277,6 +277,9 @@ struct kvm_vcpu {
gpa_t mmio_phys_addr;
int pio_pending;

+ int sigset_active;
+ sigset_t sigset;
+
struct {
int active;
u8 save_iopl;
diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index ac44df5..df85f5f 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -1591,9 +1591,13 @@ static void complete_pio(struct kvm_vcpu *vcpu)
static int kvm_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
{
int r;
+ sigset_t sigsaved;

vcpu_load(vcpu);

+ if (vcpu->sigset_active)
+ sigprocmask(SIG_SETMASK, &vcpu->sigset, &sigsaved);
+
/* re-sync apic's tpr */
vcpu->cr8 = kvm_run->cr8;

@@ -1616,6 +1620,9 @@ static int kvm_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)

r = kvm_arch_ops->run(vcpu, kvm_run);

+ if (vcpu->sigset_active)
+ sigprocmask(SIG_SETMASK, &sigsaved, NULL);
+
vcpu_put(vcpu);
return r;
}
@@ -2142,6 +2149,17 @@ out:
return r;
}

+static int kvm_vcpu_ioctl_set_sigmask(struct kvm_vcpu *vcpu, sigset_t *sigset)
+{
+ if (sigset) {
+ sigdelsetmask(sigset, sigmask(SIGKILL)|sigmask(SIGSTOP));
+ vcpu->sigset_active = 1;
+ vcpu->sigset = *sigset;
+ } else
+ vcpu->sigset_active = 0;
+ return 0;
+}
+
static long kvm_vcpu_ioctl(struct file *filp,
unsigned int ioctl, unsigned long arg)
{
@@ -2260,6 +2278,29 @@ static long kvm_vcpu_ioctl(struct file *filp,
goto out;
break;
}
+ case KVM_SET_SIGNAL_MASK: {
+ struct kvm_signal_mask __user *sigmask_arg = argp;
+ struct kvm_signal_mask kvm_sigmask;
+ sigset_t sigset, *p;
+
+ p = NULL;
+ if (argp) {
+ r = -EFAULT;
+ if (copy_from_user(&kvm_sigmask, argp,
+ sizeof kvm_sigmask))
+ goto out;
+ r = -EINVAL;
+ if (kvm_sigmask.len != sizeof sigset)
+ goto out;
+ r = -EFAULT;
+ if (copy_from_user(&sigset, sigmask_arg->sigset,
+ sizeof sigset))
+ goto out;
+ p = &sigset;
+ }
+ r = kvm_vcpu_ioctl_set_sigmask(vcpu, &sigset);
+ break;
+ }
default:
;
}
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index b3af92e..c0d10cd 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -234,6 +234,12 @@ struct kvm_cpuid {
struct kvm_cpuid_entry entries[0];
};

+/* for KVM_SET_SIGNAL_MASK */
+struct kvm_signal_mask {
+ __u32 len;
+ __u8 sigset[0];
+};
+
#define KVMIO 0xAE

/*
@@ -273,5 +279,6 @@ struct kvm_cpuid {
#define KVM_GET_MSRS _IOWR(KVMIO, 0x88, struct kvm_msrs)
#define KVM_SET_MSRS _IOW(KVMIO, 0x89, struct kvm_msrs)
#define KVM_SET_CPUID _IOW(KVMIO, 0x8a, struct kvm_cpuid)
+#define KVM_SET_SIGNAL_MASK _IOW(KVMIO, 0x8b, struct kvm_signal_mask)

#endif