From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: [PATCH 1/2] KVM: Disable large pages on misaligned memory slots Date: Mon, 8 Jun 2009 16:00:09 +0300 Message-ID: <1244466010-24909-2-git-send-email-avi@redhat.com> References: <1244466010-24909-1-git-send-email-avi@redhat.com> Cc: Marcelo Tosatti To: kvm@vger.kernel.org Return-path: Received: from mx2.redhat.com ([66.187.237.31]:54665 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754683AbZFHNAL (ORCPT ); Mon, 8 Jun 2009 09:00:11 -0400 Received: from int-mx2.corp.redhat.com (int-mx2.corp.redhat.com [172.16.27.26]) by mx2.redhat.com (8.13.8/8.13.8) with ESMTP id n58D0ETO006557 for ; Mon, 8 Jun 2009 09:00:14 -0400 In-Reply-To: <1244466010-24909-1-git-send-email-avi@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: If a slots guest physical address and host virtual address unequal (mod large page size), then we would erronously try to back guest large pages with host large pages. Detect this misalignment and diable large page support for the trouble slot. Signed-off-by: Avi Kivity --- virt/kvm/kvm_main.c | 10 +++++++++- 1 files changed, 9 insertions(+), 1 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 9c99307..b9ca73c 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1086,7 +1086,7 @@ int __kvm_set_memory_region(struct kvm *kvm, { int r; gfn_t base_gfn; - unsigned long npages; + unsigned long npages, ugfn; int largepages; unsigned long i; struct kvm_memory_slot *memslot; @@ -1177,6 +1177,14 @@ int __kvm_set_memory_region(struct kvm *kvm, new.lpage_info[0].write_count = 1; if ((base_gfn+npages) % KVM_PAGES_PER_HPAGE) new.lpage_info[largepages-1].write_count = 1; + ugfn = new.userspace_addr >> PAGE_SHIFT; + /* + * If the gfn and userspace address are not aligned wrt each + * other, disable large page support for this slot + */ + if ((base_gfn ^ ugfn) & (KVM_PAGES_PER_HPAGE - 1)) + for (i = 0; i < largepages; ++i) + new.lpage_info[i].write_count = 1; } /* Allocate page dirty bitmap if needed */ -- 1.6.0.6