diff options
| author | James Hogan <james.hogan@imgtec.com> | 2016-04-22 10:38:46 +0100 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2016-05-10 15:56:50 +0200 |
| commit | b45bacd2d048f405c7760e5cc9b60dd67708734f (patch) | |
| tree | e4085212040106f1403baab0c681cd0ec06bb6b8 /arch/mips/kvm/trap_emul.c | |
| parent | 4355c44f063d3de4f072d796604c7f4ba4085cc3 (diff) | |
| download | linux-b45bacd2d048f405c7760e5cc9b60dd67708734f.tar.gz | |
MIPS: KVM: Fix timer IRQ race when writing CP0_Compare
Writing CP0_Compare clears the timer interrupt pending bit
(CP0_Cause.TI), but this wasn't being done atomically. If a timer
interrupt raced with the write of the guest CP0_Compare, the timer
interrupt could end up being pending even though the new CP0_Compare is
nowhere near CP0_Count.
We were already updating the hrtimer expiry with
kvm_mips_update_hrtimer(), which used both kvm_mips_freeze_hrtimer() and
kvm_mips_resume_hrtimer(). Close the race window by expanding out
kvm_mips_update_hrtimer(), and clearing CP0_Cause.TI and setting
CP0_Compare between the freeze and resume. Since the pending timer
interrupt should not be cleared when CP0_Compare is written via the KVM
user API, an ack argument is added to distinguish the source of the
write.
Fixes: e30492bbe95a ("MIPS: KVM: Rewrite count/compare timer emulation")
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim KrÄmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Cc: <stable@vger.kernel.org> # 3.16.x-
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/mips/kvm/trap_emul.c')
| -rw-r--r-- | arch/mips/kvm/trap_emul.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/mips/kvm/trap_emul.c b/arch/mips/kvm/trap_emul.c index c4038d2a724c..caa5ea1038a0 100644 --- a/arch/mips/kvm/trap_emul.c +++ b/arch/mips/kvm/trap_emul.c @@ -546,7 +546,7 @@ static int kvm_trap_emul_set_one_reg(struct kvm_vcpu *vcpu, kvm_mips_write_count(vcpu, v); break; case KVM_REG_MIPS_CP0_COMPARE: - kvm_mips_write_compare(vcpu, v); + kvm_mips_write_compare(vcpu, v, false); break; case KVM_REG_MIPS_CP0_CAUSE: /* |