[Linux-stable-mirror] Patch "KVM: Let KVM_SET_SIGNAL_MASK work as advertised" has been added to the 4.14-stable tree

1 Feb 2018

This is a note to let you know that I've just added the patch titled
KVM: Let KVM_SET_SIGNAL_MASK work as advertised
to the 4.14-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is:
     kvm-let-kvm_set_signal_mask-work-as-advertised.patch
and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let stable@vger.kernel.org know about it.
...
From foo@baz Thu Feb  1 13:45:42 CET 2018
From: "Jan H. Schönherr" jschoenh@amazon.de
Date: Fri, 24 Nov 2017 22:39:01 +0100
Subject: KVM: Let KVM_SET_SIGNAL_MASK work as advertised
From: "Jan H. Schönherr" jschoenh@amazon.de
[ Upstream commit 20b7035c66bacc909ae3ffe92c1a1ea7db99fe4f ]
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. SchÃÂ¶nherr jschoenh@amazon.de
Signed-off-by: Paolo Bonzini pbonzini@redhat.com
Signed-off-by: Sasha Levin alexander.levin@verizon.com
Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
---
 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(-)

--- a/arch/mips/kvm/mips.c
+++ b/arch/mips/kvm/mips.c
@@ -445,10 +445,8 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(
 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_v
    local_irq_enable();
out:
-	if (vcpu->sigset_active)
-		sigprocmask(SIG_SETMASK, &sigsaved, NULL);
+	kvm_sigset_deactivate(vcpu);
return r;
 }
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -1407,7 +1407,6 @@ int kvm_vcpu_ioctl_set_one_reg(struct kv
 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_v
 #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;
 }
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -3378,7 +3378,6 @@ static void store_regs(struct kvm_vcpu *
 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;
@@ -3388,8 +3387,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_v
    	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);
@@ -3423,8 +3421,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_v
    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;
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7245,12 +7245,10 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_v
 {
    struct fpu *fpu = &current->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) {
@@ -7293,8 +7291,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_v
out:
    post_kvm_run_save(vcpu);
-	if (vcpu->sigset_active)
-		sigprocmask(SIG_SETMASK, &sigsaved, NULL);
+	kvm_sigset_deactivate(vcpu);
return r;
 }
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -714,6 +714,9 @@ int kvm_vcpu_write_guest(struct kvm_vcpu
    		 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);
--- a/virt/kvm/arm/arm.c
+++ b/virt/kvm/arm/arm.c
@@ -612,7 +612,6 @@ static void check_vcpu_requests(struct k
 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;
@@ -630,8 +629,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_v
    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;
@@ -753,8 +751,8 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_v
    	kvm_pmu_update_run(vcpu);
    }
-	if (vcpu->sigset_active)
-		sigprocmask(SIG_SETMASK, &sigsaved, NULL);
+	kvm_sigset_deactivate(vcpu);
+
    return ret;
 }
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2073,6 +2073,29 @@ void kvm_vcpu_mark_page_dirty(struct kvm
 }
 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, &current->real_blocked);
+}
+
+void kvm_sigset_deactivate(struct kvm_vcpu *vcpu)
+{
+	if (!vcpu->sigset_active)
+		return;
+
+	sigprocmask(SIG_SETMASK, &current->real_blocked, NULL);
+	sigemptyset(&current->real_blocked);
+}
+
 static void grow_halt_poll_ns(struct kvm_vcpu *vcpu)
 {
    unsigned int old, val, grow;
Patches currently in stable-queue which might be from jschoenh@amazon.de are
queue-4.14/kvm-let-kvm_set_signal_mask-work-as-advertised.patch

    

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[Linux-stable-mirror] Patch "KVM: Let KVM_SET_SIGNAL_MASK work as advertised" has been added to the 4.14-stable tree