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Commit fa6b7fe9 authored by Cornelia Huck's avatar Cornelia Huck Committed by Marcelo Tosatti
Browse files

KVM: s390: Add support for channel I/O instructions. 



Add a new capability, KVM_CAP_S390_CSS_SUPPORT, which will pass
intercepts for channel I/O instructions to userspace. Only I/O
instructions interacting with I/O interrupts need to be handled
in-kernel:

- TEST PENDING INTERRUPTION (tpi) dequeues and stores pending
  interrupts entirely in-kernel.
- TEST SUBCHANNEL (tsch) dequeues pending interrupts in-kernel
  and exits via KVM_EXIT_S390_TSCH to userspace for subchannel-
  related processing.

Reviewed-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
Reviewed-by: default avatarAlexander Graf <agraf@suse.de>
Signed-off-by: default avatarCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent d6712df9

Documentation/virtual/kvm/api.txt

+30 −0
Original line number Diff line number Diff line
@@ -2350,6 +2350,22 @@ The possible hypercalls are defined in the Power Architecture Platform 
Requirements (PAPR) document available from www.power.org (free

developer registration required to access it).



		/* KVM_EXIT_S390_TSCH */

		struct {

			__u16 subchannel_id;

			__u16 subchannel_nr;

			__u32 io_int_parm;

			__u32 io_int_word;

			__u32 ipb;

			__u8 dequeued;

		} s390_tsch;



s390 specific. This exit occurs when KVM_CAP_S390_CSS_SUPPORT has been enabled

and TEST SUBCHANNEL was intercepted. If dequeued is set, a pending I/O

interrupt for the target subchannel has been dequeued and subchannel_id,

subchannel_nr, io_int_parm and io_int_word contain the parameters for that

interrupt. ipb is needed for instruction parameter decoding.



		/* Fix the size of the union. */

		char padding[256];

	};
@@ -2471,3 +2487,17 @@ For mmu types KVM_MMU_FSL_BOOKE_NOHV and KVM_MMU_FSL_BOOKE_HV: 
   where "num_sets" is the tlb_sizes[] value divided by the tlb_ways[] value.

 - The tsize field of mas1 shall be set to 4K on TLB0, even though the

   hardware ignores this value for TLB0.



6.4 KVM_CAP_S390_CSS_SUPPORT



Architectures: s390

Parameters: none

Returns: 0 on success; -1 on error



This capability enables support for handling of channel I/O instructions.



TEST PENDING INTERRUPTION and the interrupt portion of TEST SUBCHANNEL are

handled in-kernel, while the other I/O instructions are passed to userspace.



When this capability is enabled, KVM_EXIT_S390_TSCH will occur on TEST

SUBCHANNEL intercepts.

arch/s390/include/asm/kvm_host.h

+1 −0
Original line number Diff line number Diff line
@@ -262,6 +262,7 @@ struct kvm_arch{ 
	debug_info_t *dbf;

	struct kvm_s390_float_interrupt float_int;

	struct gmap *gmap;

	int css_support;

};



extern int sie64a(struct kvm_s390_sie_block *, u64 *);

arch/s390/kvm/intercept.c

+1 −0
Original line number Diff line number Diff line
@@ -264,6 +264,7 @@ static const intercept_handler_t intercept_funcs[] = { 
	[0x0C >> 2] = handle_instruction_and_prog,

	[0x10 >> 2] = handle_noop,

	[0x14 >> 2] = handle_noop,

	[0x18 >> 2] = handle_noop,

	[0x1C >> 2] = kvm_s390_handle_wait,

	[0x20 >> 2] = handle_validity,

	[0x28 >> 2] = handle_stop,

arch/s390/kvm/interrupt.c

+37 −0
Original line number Diff line number Diff line
@@ -709,6 +709,43 @@ int kvm_s390_inject_program_int(struct kvm_vcpu *vcpu, u16 code) 
	return 0;

}



struct kvm_s390_interrupt_info *kvm_s390_get_io_int(struct kvm *kvm,

						    u64 cr6, u64 schid)

{

	struct kvm_s390_float_interrupt *fi;

	struct kvm_s390_interrupt_info *inti, *iter;



	if ((!schid && !cr6) || (schid && cr6))

		return NULL;

	mutex_lock(&kvm->lock);

	fi = &kvm->arch.float_int;

	spin_lock(&fi->lock);

	inti = NULL;

	list_for_each_entry(iter, &fi->list, list) {

		if (!is_ioint(iter->type))

			continue;

		if (cr6 && ((cr6 & iter->io.io_int_word) == 0))

			continue;

		if (schid) {

			if (((schid & 0x00000000ffff0000) >> 16) !=

			    iter->io.subchannel_id)

				continue;

			if ((schid & 0x000000000000ffff) !=

			    iter->io.subchannel_nr)

				continue;

		}

		inti = iter;

		break;

	}

	if (inti)

		list_del_init(&inti->list);

	if (list_empty(&fi->list))

		atomic_set(&fi->active, 0);

	spin_unlock(&fi->lock);

	mutex_unlock(&kvm->lock);

	return inti;

}



int kvm_s390_inject_vm(struct kvm *kvm,

		       struct kvm_s390_interrupt *s390int)

{

arch/s390/kvm/kvm-s390.c

+12 −0
Original line number Diff line number Diff line
@@ -141,6 +141,7 @@ int kvm_dev_ioctl_check_extension(long ext) 
	case KVM_CAP_SYNC_REGS:

	case KVM_CAP_ONE_REG:

	case KVM_CAP_ENABLE_CAP:

	case KVM_CAP_S390_CSS_SUPPORT:

		r = 1;

		break;

	case KVM_CAP_NR_VCPUS:
@@ -235,6 +236,9 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) 
		if (!kvm->arch.gmap)

			goto out_nogmap;

	}



	kvm->arch.css_support = 0;



	return 0;

out_nogmap:

	debug_unregister(kvm->arch.dbf);
@@ -658,6 +662,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run) 
	case KVM_EXIT_INTR:

	case KVM_EXIT_S390_RESET:

	case KVM_EXIT_S390_UCONTROL:

	case KVM_EXIT_S390_TSCH:

		break;

	default:

		BUG();
@@ -818,6 +823,13 @@ static int kvm_vcpu_ioctl_enable_cap(struct kvm_vcpu *vcpu, 
		return -EINVAL;



	switch (cap->cap) {

	case KVM_CAP_S390_CSS_SUPPORT:

		if (!vcpu->kvm->arch.css_support) {

			vcpu->kvm->arch.css_support = 1;

			trace_kvm_s390_enable_css(vcpu->kvm);

		}

		r = 0;

		break;

	default:

		r = -EINVAL;

		break;