Re: [GIT PULL 1/6] KVM: s390: Handle MVPG partial execution interception

[Heiko Carstens <heiko.carstens@de.ibm.com>]

On Tue, Apr 29, 2014 at 03:36:43PM +0200, Christian Borntraeger wrote:
> +static int handle_mvpg_pei(struct kvm_vcpu *vcpu)
> +{
> +	unsigned long hostaddr, srcaddr, dstaddr;
> +	psw_t *psw = &vcpu->arch.sie_block->gpsw;
> +	struct mm_struct *mm = current->mm;
> +	int reg1, reg2, rc;
> +
> +	kvm_s390_get_regs_rre(vcpu, &reg1, &reg2);
> +	srcaddr = kvm_s390_real_to_abs(vcpu, vcpu->run->s.regs.gprs[reg2]);
> +	dstaddr = kvm_s390_real_to_abs(vcpu, vcpu->run->s.regs.gprs[reg1]);
> +
> +	/* Make sure that the source is paged-in */
> +	hostaddr = gmap_fault(srcaddr, vcpu->arch.gmap);
> +	if (IS_ERR_VALUE(hostaddr))
> +		return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);

FWIW (and nothing that should keep this code from going upstream),
this is not entirely correct, since gmap_fault() may return -ENOMEM.
So a host out-of-memory situation will incorrectly result in a guest
addressing exception, which is most likely not what we want.