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| author | David Hildenbrand <dahi@linux.vnet.ibm.com> | 2014-03-18 10:06:14 +0100 |
|---|---|---|
| committer | Christian Borntraeger <borntraeger@de.ibm.com> | 2014-04-22 13:24:52 +0200 |
| commit | f71d0dc5084b4de761b5be1aef1a855136cecd15 (patch) | |
| tree | bee07d8a60a7a01c8556fd102ca8572fd8ab8dba /arch/s390 | |
| parent | KVM: s390: move timer interrupt checks into own functions (diff) | |
| download | linux-f71d0dc5084b4de761b5be1aef1a855136cecd15.tar.xz linux-f71d0dc5084b4de761b5be1aef1a855136cecd15.zip | |
KVM: s390: no timer interrupts when single-stepping a guest
When a guest is single-stepped, we want to disable timer interrupts. Otherwise,
the guest will continuously execute the external interrupt handler and make
debugging of code where timer interrupts are enabled almost impossible.
The delivery of timer interrupts can be enforced in such sections by setting a
breakpoint and continuing execution.
In order to disable timer interrupts, they are disabled in the control register
of the guest just before SIE entry and are suppressed in the interrupt
check/delivery methods.
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Diffstat (limited to 'arch/s390')
| -rw-r--r-- | arch/s390/kvm/guestdbg.c | 2 | ||||
| -rw-r--r-- | arch/s390/kvm/interrupt.c | 3 |
2 files changed, 5 insertions, 0 deletions
diff --git a/arch/s390/kvm/guestdbg.c b/arch/s390/kvm/guestdbg.c index 100e99d1030d..757ccef62fd5 100644 --- a/arch/s390/kvm/guestdbg.c +++ b/arch/s390/kvm/guestdbg.c @@ -155,6 +155,8 @@ void kvm_s390_patch_guest_per_regs(struct kvm_vcpu *vcpu) */ if (guestdbg_sstep_enabled(vcpu)) { + /* disable timer (clock-comparator) interrupts */ + vcpu->arch.sie_block->gcr[0] &= ~0x800ul; vcpu->arch.sie_block->gcr[9] |= PER_EVENT_IFETCH; vcpu->arch.sie_block->gcr[10] = 0; vcpu->arch.sie_block->gcr[11] = PSW_ADDR_INSN; diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c index 0165f1b089ac..d020c5f8eabb 100644 --- a/arch/s390/kvm/interrupt.c +++ b/arch/s390/kvm/interrupt.c @@ -61,6 +61,9 @@ static int ckc_interrupts_enabled(struct kvm_vcpu *vcpu) if (psw_extint_disabled(vcpu) || !(vcpu->arch.sie_block->gcr[0] & 0x800ul)) return 0; + if (guestdbg_enabled(vcpu) && guestdbg_sstep_enabled(vcpu)) + /* No timer interrupts when single stepping */ + return 0; return 1; } |