Commit b0ad874d authored by Eric Farman's avatar Eric Farman Committed by Janosch Frank
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KVM: s390: vsie: Allow non-zarch guests 



Linux/KVM runs in z/Architecture-only mode. Although z/Architecture
is built upon a long history of hardware refinements, any other
CPU mode is not permitted.

Allow a userspace to explicitly enable the use of ESA mode for
nested guests, otherwise usage will be rejected.

Reviewed-by: default avatarJanosch Frank <frankja@linux.ibm.com>
Signed-off-by: default avatarEric Farman <farman@linux.ibm.com>
Reviewed-by: default avatarHendrik Brueckner <brueckner@linux.ibm.com>
Reviewed-by: default avatarChristian Borntraeger <borntraeger@linux.ibm.com>
Signed-off-by: default avatarJanosch Frank <frankja@linux.ibm.com>
parent 1653545a

arch/s390/include/asm/kvm_host.h

+1 −0
Original line number Diff line number Diff line
@@ -656,6 +656,7 @@ struct kvm_arch { 
	int user_stsi;

	int user_instr0;

	int user_operexec;

	int allow_vsie_esamode;

	struct s390_io_adapter *adapters[MAX_S390_IO_ADAPTERS];

	wait_queue_head_t ipte_wq;

	int ipte_lock_count;

arch/s390/kvm/vsie.c

+5 −3
Original line number Diff line number Diff line
@@ -125,8 +125,8 @@ static int prepare_cpuflags(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page) 
	struct kvm_s390_sie_block *scb_o = vsie_page->scb_o;

	int newflags, cpuflags = atomic_read(&scb_o->cpuflags);



	/* we don't allow ESA/390 guests */

	if (!(cpuflags & CPUSTAT_ZARCH))

	/* we don't allow ESA/390 guests unless explicitly enabled */

	if (!(cpuflags & CPUSTAT_ZARCH) && !vcpu->kvm->arch.allow_vsie_esamode)

		return set_validity_icpt(scb_s, 0x0001U);



	if (cpuflags & (CPUSTAT_RRF | CPUSTAT_MCDS))
@@ -135,6 +135,8 @@ static int prepare_cpuflags(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page) 
		return set_validity_icpt(scb_s, 0x0007U);



	/* intervention requests will be set later */

	newflags = 0;

	if (cpuflags & CPUSTAT_ZARCH)

		newflags = CPUSTAT_ZARCH;

	if (cpuflags & CPUSTAT_GED && test_kvm_facility(vcpu->kvm, 8))

		newflags |= CPUSTAT_GED;