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From 38c385caa32752ef176ffd1448e45e0dc94d5043 Mon Sep 17 00:00:00 2001
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From: Orit Wasserman <owasserm@redhat.com>
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Date: Wed, 9 Oct 2013 10:09:11 +0200
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Subject: [PATCH 16/25] Fix real mode guest segments dpl value in savevm
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RH-Author: Orit Wasserman <owasserm@redhat.com>
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Message-id: <1381313355-15641-7-git-send-email-owasserm@redhat.com>
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Patchwork-id: 54802
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O-Subject: [RHEL7.0 qemu-kvm v2 06/10] Fix real mode guest segments dpl value in savevm
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Bugzilla: 921465
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RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Juan Quintela <quintela@redhat.com>
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Older KVM version put invalid value in the segments registers dpl field for
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real mode guests (0x3).
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This breaks migration from those hosts to hosts with unrestricted guest support.
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We detect it by checking CS dpl value for real mode guest and fix the dpl values
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of all the segment registers.
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Signed-off-by: Orit Wasserman <owasserm@redhat.com>
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Reviewed-by: Juan Quintela <quintela@redhat.com>
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Signed-off-by: Juan Quintela <quintela@redhat.com>
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(cherry picked from commit 3e47c249b93d5cc1e0f9404dbe243682598ba8fb)
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---
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 target-i386/machine.c | 18 ++++++++++++++++++
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 1 file changed, 18 insertions(+)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 target-i386/machine.c |   18 ++++++++++++++++++
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 1 files changed, 18 insertions(+), 0 deletions(-)
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diff --git a/target-i386/machine.c b/target-i386/machine.c
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index 079a132..8faea62 100644
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--- a/target-i386/machine.c
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+++ b/target-i386/machine.c
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@@ -252,6 +252,24 @@ static void cpu_pre_save(void *opaque)
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     }
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     env->fpregs_format_vmstate = 0;
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+
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+    /*
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+     * Real mode guest segments register DPL should be zero.
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+     * Older KVM version were setting it wrongly.
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+     * Fixing it will allow live migration to host with unrestricted guest
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+     * support (otherwise the migration will fail with invalid guest state
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+     * error).
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+     */
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+    if (!(env->cr[0] & CR0_PE_MASK) &&
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+        (env->segs[R_CS].flags >> DESC_DPL_SHIFT & 3) != 0) {
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+        env->segs[R_CS].flags &= ~(env->segs[R_CS].flags & DESC_DPL_MASK);
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+        env->segs[R_DS].flags &= ~(env->segs[R_DS].flags & DESC_DPL_MASK);
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+        env->segs[R_ES].flags &= ~(env->segs[R_ES].flags & DESC_DPL_MASK);
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+        env->segs[R_FS].flags &= ~(env->segs[R_FS].flags & DESC_DPL_MASK);
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+        env->segs[R_GS].flags &= ~(env->segs[R_GS].flags & DESC_DPL_MASK);
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+        env->segs[R_SS].flags &= ~(env->segs[R_SS].flags & DESC_DPL_MASK);
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+    }
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+
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 }
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 static int cpu_post_load(void *opaque, int version_id)
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-- 
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1.7.1
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