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| author | Michael Mueller <mimu@linux.vnet.ibm.com> | 2017-06-29 18:39:27 +0200 |
|---|---|---|
| committer | Christian Borntraeger <borntraeger@de.ibm.com> | 2018-01-26 09:49:09 +0100 |
| commit | c7901a6ebee4b624971361bbd93f21ab0b359786 (patch) | |
| tree | 8247eb88130353574f5f2fa35452059ac7c7dd40 /arch/s390/kvm/interrupt.c | |
| parent | 8d5fb0dc4ec069ea02395593e9b6b2b39a92457e (diff) | |
| download | linux-c7901a6ebee4b624971361bbd93f21ab0b359786.tar.gz linux-c7901a6ebee4b624971361bbd93f21ab0b359786.tar.bz2 linux-c7901a6ebee4b624971361bbd93f21ab0b359786.zip | |
KVM: s390: reverse bit ordering of irqs in pending mask
This patch prepares a simplification of bit operations between the irq
pending mask for emulated interrupts and the Interruption Pending Mask
(IPM) which is part of the Guest Interruption State Area (GISA), a feature
that allows interrupt delivery to guests by means of the SIE instruction.
Without that change, a bit-wise *or* operation on parts of these two masks
would either require a look-up table of size 256 bytes to map the IPM
to the emulated irq pending mask bit orientation (all bits mirrored at half
byte) or a sequence of up to 8 condidional branches to perform tests of
single bit positions. Both options are to be rejected either by performance
or space utilization reasons.
Beyond that this change will be transparent.
Signed-off-by: Michael Mueller <mimu@linux.vnet.ibm.com>
Reviewed-by: Halil Pasic <pasic@linux.vnet.ibm.com>
Reviewed-by: Pierre Morel <pmorel@linux.vnet.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Diffstat (limited to 'arch/s390/kvm/interrupt.c')
| -rw-r--r-- | arch/s390/kvm/interrupt.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c index 4b483b48436a..b731d4fede83 100644 --- a/arch/s390/kvm/interrupt.c +++ b/arch/s390/kvm/interrupt.c @@ -189,8 +189,8 @@ static int cpu_timer_irq_pending(struct kvm_vcpu *vcpu) static inline int is_ioirq(unsigned long irq_type) { - return ((irq_type >= IRQ_PEND_IO_ISC_0) && - (irq_type <= IRQ_PEND_IO_ISC_7)); + return ((irq_type >= IRQ_PEND_IO_ISC_7) && + (irq_type <= IRQ_PEND_IO_ISC_0)); } static uint64_t isc_to_isc_bits(int isc) @@ -211,12 +211,12 @@ static inline unsigned long pending_irqs(struct kvm_vcpu *vcpu) static inline int isc_to_irq_type(unsigned long isc) { - return IRQ_PEND_IO_ISC_0 + isc; + return IRQ_PEND_IO_ISC_0 - isc; } static inline int irq_type_to_isc(unsigned long irq_type) { - return irq_type - IRQ_PEND_IO_ISC_0; + return IRQ_PEND_IO_ISC_0 - irq_type; } static unsigned long disable_iscs(struct kvm_vcpu *vcpu, @@ -1149,8 +1149,8 @@ int __must_check kvm_s390_deliver_pending_interrupts(struct kvm_vcpu *vcpu) set_bit(IRQ_PEND_EXT_CPU_TIMER, &li->pending_irqs); while ((irqs = deliverable_irqs(vcpu)) && !rc) { - /* bits are in the order of interrupt priority */ - irq_type = find_first_bit(&irqs, IRQ_PEND_COUNT); + /* bits are in the reverse order of interrupt priority */ + irq_type = find_last_bit(&irqs, IRQ_PEND_COUNT); if (is_ioirq(irq_type)) { rc = __deliver_io(vcpu, irq_type); } else { |