From 232b8e3b1d4946a45e3b9dd4c282b12a085dd39d Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Fri, 31 Mar 2017 12:50:48 +0200 Subject: [PATCH] KVM: s390: remove change-recording override support Change-recording override (CO) was never implemented in any machine. According to the architecture it is unpredictable if a translation-specification exception will be recognized if the bit is set and EDAT1 does not apply. Therefore the easiest solution is to simply ignore the bit. This also fixes commit cd1836f583d7 ("KVM: s390: instruction-execution-protection support"). A guest may enable instruction-execution-protection (IEP) but not EDAT1. In such a case the guest_translate() function (arch/s390/kvm/gaccess.c) will report a specification exception on pages that have the IEP bit set while it should not. It might make sense to add full IEP support to guest_translate() and the GACC_IFETCH case. However, as far as I can tell the GACC_IFETCH case is currently only used after an instruction was executed in order to fetch the failing instruction. So there is no additional problem *currently*. Fixes: cd1836f583d7 ("KVM: s390: instruction-execution-protection support") Signed-off-by: Heiko Carstens Signed-off-by: Christian Borntraeger --- arch/s390/kvm/gaccess.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/arch/s390/kvm/gaccess.c b/arch/s390/kvm/gaccess.c index d55c829a5944..ddbffb715b40 100644 --- a/arch/s390/kvm/gaccess.c +++ b/arch/s390/kvm/gaccess.c @@ -168,8 +168,7 @@ union page_table_entry { unsigned long z : 1; /* Zero Bit */ unsigned long i : 1; /* Page-Invalid Bit */ unsigned long p : 1; /* DAT-Protection Bit */ - unsigned long co : 1; /* Change-Recording Override */ - unsigned long : 8; + unsigned long : 9; }; }; @@ -745,8 +744,6 @@ static unsigned long guest_translate(struct kvm_vcpu *vcpu, unsigned long gva, return PGM_PAGE_TRANSLATION; if (pte.z) return PGM_TRANSLATION_SPEC; - if (pte.co && !edat1) - return PGM_TRANSLATION_SPEC; dat_protection |= pte.p; raddr.pfra = pte.pfra; real_address: @@ -1182,7 +1179,7 @@ int kvm_s390_shadow_fault(struct kvm_vcpu *vcpu, struct gmap *sg, rc = gmap_read_table(sg->parent, pgt + vaddr.px * 8, &pte.val); if (!rc && pte.i) rc = PGM_PAGE_TRANSLATION; - if (!rc && (pte.z || (pte.co && sg->edat_level < 1))) + if (!rc && pte.z) rc = PGM_TRANSLATION_SPEC; shadow_page: pte.p |= dat_protection; -- 2.20.1