Commit c7901a6e authored by Michael Mueller's avatar Michael Mueller Committed by Christian Borntraeger
Browse files

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: default avatarMichael Mueller <mimu@linux.vnet.ibm.com>
Reviewed-by: default avatarHalil Pasic <pasic@linux.vnet.ibm.com>
Reviewed-by: default avatarPierre Morel <pmorel@linux.vnet.ibm.com>
Reviewed-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: default avatarCornelia Huck <cohuck@redhat.com>
Reviewed-by: default avatarDavid Hildenbrand <david@redhat.com>
Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
parent 8d5fb0dc

arch/s390/include/asm/kvm_host.h

+27 −27
Original line number Diff line number Diff line
@@ -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

};

arch/s390/kvm/interrupt.c

+6 −6
Original line number Diff line number Diff line
@@ -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 {

CRA Git | Maintained and supported by SUSTech CRA and CCSE