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Fix real mode guest segments dpl value in savevm 

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 <owasserm@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
This commit is contained in:
Orit Wasserman 2013-07-22 20:29:42 +03:00 committed by Juan Quintela
parent 444ba6797e
commit 3e47c249b9
1 changed files with 18 additions and 0 deletions
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18
target-i386/machine.c
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@ -252,6 +252,24 @@ static void cpu_pre_save(void *opaque)
}
env->fpregs_format_vmstate = 0;
/*
* 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_post_load(void *opaque, int version_id)