From efc8397cccbc8fa61b0811cf6bb23c7d34687268 Mon Sep 17 00:00:00 2001 Message-Id: In-Reply-To: References: From: Orit Wasserman Date: Wed, 24 Jul 2013 13:49:59 +0200 Subject: [PATCH 3/4] Fix real mode guest segments dpl value in savevm RH-Author: Orit Wasserman Message-id: <1374673799-1452-3-git-send-email-owasserm@redhat.com> Patchwork-id: 52696 O-Subject: [RHEL6.5 qemu-kvm PATCH 2/2] Fix real mode guest segments dpl value in savevm Bugzilla: 888767 RH-Acked-by: Paolo Bonzini RH-Acked-by: Gleb Natapov RH-Acked-by: Juan Quintela Older KVM version put invalid value in the segments registers dpl field for real mode guests (0x3). This breaks migration from those hosts to hosts with unrestricted guest support. We detect it by checking CS dpl value for real mode guest and fix the dpl values of all the segment registers. Signed-off-by: Orit Wasserman --- target-i386/machine.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) Signed-off-by: Michal Novotny --- target-i386/machine.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/target-i386/machine.c b/target-i386/machine.c index 7e61887..b623d4d 100644 --- a/target-i386/machine.c +++ b/target-i386/machine.c @@ -356,6 +356,23 @@ static void cpu_pre_save(void *opaque) #else env->fpregs_format_vmstate = 1; #endif + + /* + * Real mode guest segments register DPL should be zero. + * Older KVM version were setting it wrongly. + * Fixing it will allow live migration to host with unrestricted guest + * support (otherwise the migration will fail with invalid guest state + * error). + */ + if (!(env->cr[0] & CR0_PE_MASK) && + (env->segs[R_CS].flags >> DESC_DPL_SHIFT & 3) != 0) { + env->segs[R_CS].flags &= ~(env->segs[R_CS].flags & DESC_DPL_MASK); + env->segs[R_DS].flags &= ~(env->segs[R_DS].flags & DESC_DPL_MASK); + env->segs[R_ES].flags &= ~(env->segs[R_ES].flags & DESC_DPL_MASK); + env->segs[R_FS].flags &= ~(env->segs[R_FS].flags & DESC_DPL_MASK); + env->segs[R_GS].flags &= ~(env->segs[R_GS].flags & DESC_DPL_MASK); + env->segs[R_SS].flags &= ~(env->segs[R_SS].flags & DESC_DPL_MASK); + } } static int cpu_pre_load(void *opaque) -- 1.7.11.7