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KVM: s390: reverse bit ordering of irqs in pending mask

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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>
This commit is contained in:
Michael Mueller 2017-06-29 18:39:27 +02:00 committed by Christian Borntraeger
parent 8d5fb0dc4e
commit c7901a6ebe
2 changed files with 33 additions and 33 deletions
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54
arch/s390/include/asm/kvm_host.h
View File

@ -422,35 +422,35 @@ struct kvm_vcpu_stat {
#define PGM_PER 0x80
#define PGM_CRYPTO_OPERATION 0x119
/* irq types in order of priority */
/* irq types in ascend order of priorities */
enum irq_types {
IRQ_PEND_MCHK_EX = 0,
IRQ_PEND_SVC,
IRQ_PEND_PROG,
IRQ_PEND_MCHK_REP,
IRQ_PEND_EXT_IRQ_KEY,
IRQ_PEND_EXT_MALFUNC,
IRQ_PEND_EXT_EMERGENCY,
IRQ_PEND_EXT_EXTERNAL,
IRQ_PEND_EXT_CLOCK_COMP,
IRQ_PEND_EXT_CPU_TIMER,
IRQ_PEND_EXT_TIMING,
IRQ_PEND_EXT_SERVICE,
IRQ_PEND_EXT_HOST,
IRQ_PEND_PFAULT_INIT,
IRQ_PEND_PFAULT_DONE,
IRQ_PEND_VIRTIO,
IRQ_PEND_IO_ISC_0,
IRQ_PEND_IO_ISC_1,
IRQ_PEND_IO_ISC_2,
IRQ_PEND_IO_ISC_3,
IRQ_PEND_IO_ISC_4,
IRQ_PEND_IO_ISC_5,
IRQ_PEND_IO_ISC_6,
IRQ_PEND_IO_ISC_7,
IRQ_PEND_SIGP_STOP,
IRQ_PEND_SET_PREFIX = 0,
IRQ_PEND_RESTART,
IRQ_PEND_SET_PREFIX,
IRQ_PEND_SIGP_STOP,
IRQ_PEND_IO_ISC_7,
IRQ_PEND_IO_ISC_6,
IRQ_PEND_IO_ISC_5,
IRQ_PEND_IO_ISC_4,
IRQ_PEND_IO_ISC_3,
IRQ_PEND_IO_ISC_2,
IRQ_PEND_IO_ISC_1,
IRQ_PEND_IO_ISC_0,
IRQ_PEND_VIRTIO,
IRQ_PEND_PFAULT_DONE,
IRQ_PEND_PFAULT_INIT,
IRQ_PEND_EXT_HOST,
IRQ_PEND_EXT_SERVICE,
IRQ_PEND_EXT_TIMING,
IRQ_PEND_EXT_CPU_TIMER,
IRQ_PEND_EXT_CLOCK_COMP,
IRQ_PEND_EXT_EXTERNAL,
IRQ_PEND_EXT_EMERGENCY,
IRQ_PEND_EXT_MALFUNC,
IRQ_PEND_EXT_IRQ_KEY,
IRQ_PEND_MCHK_REP,
IRQ_PEND_PROG,
IRQ_PEND_SVC,
IRQ_PEND_MCHK_EX,
IRQ_PEND_COUNT
};

12
arch/s390/kvm/interrupt.c
View File

@ -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 {