KVM API says for the signal mask you set via KVM_SET_SIGNAL_MASK, that
"any unblocked signal received [...] will cause KVM_RUN to return with
-EINTR" and that "the signal will only be delivered if not blocked by
the original signal mask".
This, however, is only true, when the calling task has a signal handler
registered for a signal. If not, signal evaluation is short-circuited for
SIG_IGN and SIG_DFL, and the signal is either ignored without KVM_RUN
returning or the whole process is terminated.
Make KVM_SET_SIGNAL_MASK behave as advertised by utilizing logic similar
to that in do_sigtimedwait() to avoid short-circuiting of signals.
Signed-off-by: Jan H. Schönherr <jschoenh@xxxxxxxxx>
---
Note: Only tested on x86.
---
arch/mips/kvm/mips.c | 7 ++-----
arch/powerpc/kvm/powerpc.c | 7 ++-----
arch/s390/kvm/kvm-s390.c | 7 ++-----
arch/x86/kvm/x86.c | 7 ++-----
include/linux/kvm_host.h | 3 +++
virt/kvm/arm/arm.c | 8 +++-----
virt/kvm/kvm_main.c | 23 +++++++++++++++++++++++
7 files changed, 37 insertions(+), 25 deletions(-)
diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
index d535edc..75fdeaa 100644
--- a/arch/mips/kvm/mips.c
+++ b/arch/mips/kvm/mips.c
@@ -445,10 +445,8 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
{
int r = -EINTR;
- sigset_t sigsaved;
- if (vcpu->sigset_active)
- sigprocmask(SIG_SETMASK, &vcpu->sigset, &sigsaved);
+ kvm_sigset_activate(vcpu);
if (vcpu->mmio_needed) {
if (!vcpu->mmio_is_write)
@@ -480,8 +478,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
local_irq_enable();
out:
- if (vcpu->sigset_active)
- sigprocmask(SIG_SETMASK, &sigsaved, NULL);
+ kvm_sigset_deactivate(vcpu);
return r;
}
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 6b6c53c..1915e86 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -1407,7 +1407,6 @@ int kvm_vcpu_ioctl_set_one_reg(struct kvm_vcpu *vcpu, struct kvm_one_reg *reg)
int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
{
int r;
- sigset_t sigsaved;
if (vcpu->mmio_needed) {
vcpu->mmio_needed = 0;
@@ -1448,16 +1447,14 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
#endif
}
- if (vcpu->sigset_active)
- sigprocmask(SIG_SETMASK, &vcpu->sigset, &sigsaved);
+ kvm_sigset_activate(vcpu);
if (run->immediate_exit)
r = -EINTR;
else
r = kvmppc_vcpu_run(run, vcpu);
- if (vcpu->sigset_active)
- sigprocmask(SIG_SETMASK, &sigsaved, NULL);
+ kvm_sigset_deactivate(vcpu);
return r;
}
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 98ad8b9..9614aea 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -3372,7 +3372,6 @@ static void store_regs(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
{
int rc;
- sigset_t sigsaved;
if (kvm_run->immediate_exit)
return -EINTR;
@@ -3382,8 +3381,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
return 0;
}
- if (vcpu->sigset_active)
- sigprocmask(SIG_SETMASK, &vcpu->sigset, &sigsaved);
+ kvm_sigset_activate(vcpu);
if (!kvm_s390_user_cpu_state_ctrl(vcpu->kvm)) {
kvm_s390_vcpu_start(vcpu);
@@ -3417,8 +3415,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
disable_cpu_timer_accounting(vcpu);
store_regs(vcpu, kvm_run);
- if (vcpu->sigset_active)
- sigprocmask(SIG_SETMASK, &sigsaved, NULL);
+ kvm_sigset_deactivate(vcpu);
vcpu->stat.exit_userspace++;
return rc;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 985a305..990df39 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7270,12 +7270,10 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
{
struct fpu *fpu = ¤t->thread.fpu;
int r;
- sigset_t sigsaved;
fpu__initialize(fpu);
- if (vcpu->sigset_active)
- sigprocmask(SIG_SETMASK, &vcpu->sigset, &sigsaved);
+ kvm_sigset_activate(vcpu);
if (unlikely(vcpu->arch.mp_state == KVM_MP_STATE_UNINITIALIZED)) {
if (kvm_run->immediate_exit) {
@@ -7318,8 +7316,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
out:
post_kvm_run_save(vcpu);
- if (vcpu->sigset_active)
- sigprocmask(SIG_SETMASK, &sigsaved, NULL);
+ kvm_sigset_deactivate(vcpu);
return r;
}
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 2e754b7..893d6d6 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -715,6 +715,9 @@ int kvm_vcpu_write_guest(struct kvm_vcpu *vcpu, gpa_t gpa, const void *data,
unsigned long len);
void kvm_vcpu_mark_page_dirty(struct kvm_vcpu *vcpu, gfn_t gfn);
+void kvm_sigset_activate(struct kvm_vcpu *vcpu);
+void kvm_sigset_deactivate(struct kvm_vcpu *vcpu);
+
void kvm_vcpu_block(struct kvm_vcpu *vcpu);
void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu);
void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu);
diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
index a6524ff..a67c106 100644
--- a/virt/kvm/arm/arm.c
+++ b/virt/kvm/arm/arm.c
@@ -615,7 +615,6 @@ static void check_vcpu_requests(struct kvm_vcpu *vcpu)
int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
{
int ret;
- sigset_t sigsaved;
if (unlikely(!kvm_vcpu_initialized(vcpu)))
return -ENOEXEC;
@@ -633,8 +632,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
if (run->immediate_exit)
return -EINTR;
- if (vcpu->sigset_active)
- sigprocmask(SIG_SETMASK, &vcpu->sigset, &sigsaved);
+ kvm_sigset_activate(vcpu);
ret = 1;
run->exit_reason = KVM_EXIT_UNKNOWN;
@@ -769,8 +767,8 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
kvm_pmu_update_run(vcpu);
}
- if (vcpu->sigset_active)
- sigprocmask(SIG_SETMASK, &sigsaved, NULL);
+ kvm_sigset_deactivate(vcpu);
+
return ret;
}
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 2dd1a9c..c01cff0 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2065,6 +2065,29 @@ void kvm_vcpu_mark_page_dirty(struct kvm_vcpu *vcpu, gfn_t gfn)
}
EXPORT_SYMBOL_GPL(kvm_vcpu_mark_page_dirty);
+void kvm_sigset_activate(struct kvm_vcpu *vcpu)
+{
+ if (!vcpu->sigset_active)
+ return;
+
+ /*
+ * This does a lockless modification of ->real_blocked, which is fine
+ * because, only current can change ->real_blocked and all readers of
+ * ->real_blocked don't care as long ->real_blocked is always a subset
+ * of ->blocked.
+ */
+ sigprocmask(SIG_SETMASK, &vcpu->sigset, ¤t->real_blocked);
+}
+
+void kvm_sigset_deactivate(struct kvm_vcpu *vcpu)
+{
+ if (!vcpu->sigset_active)
+ return;
+
+ sigprocmask(SIG_SETMASK, ¤t->real_blocked, NULL);
+ sigemptyset(¤t->real_blocked);
+}
+
static void grow_halt_poll_ns(struct kvm_vcpu *vcpu)
{
unsigned int old, val, grow;
--
2.3.1.dirty
