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authorAlexander Graf <agraf@suse.de>2010-01-08 02:58:04 +0100
committerMarcelo Tosatti <mtosatti@redhat.com>2010-03-01 12:35:48 -0300
commitb4433a7cceed59714b0778e1ace624befdd15ded (patch)
tree745f0477d7368155cddc363fed6e8f3dc28f83cd /arch/powerpc/kvm/emulate.c
parent7e57cba06074da84d7c24d8c3f44040d2d8c88ac (diff)
downloadlinux-b4433a7cceed59714b0778e1ace624befdd15ded.tar.bz2
KVM: PPC: Implement 'skip instruction' mode
To fetch the last instruction we were interrupted on, we enable DR in early exit code, where we are still in a very transitional phase between guest and host state. Most of the time this seemed to work, but another CPU can easily flush our TLB and HTAB which makes us go in the Linux page fault handler which totally breaks because we still use the guest's SLB entries. To work around that, let's introduce a second KVM guest mode that defines that whenever we get a trap, we don't call the Linux handler or go into the KVM exit code, but just jump over the faulting instruction. That way a potentially bad lwz doesn't trigger any faults and we can later on interpret the invalid instruction we fetched as "fetch didn't work". Signed-off-by: Alexander Graf <agraf@suse.de> Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'arch/powerpc/kvm/emulate.c')
-rw-r--r--arch/powerpc/kvm/emulate.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/powerpc/kvm/emulate.c b/arch/powerpc/kvm/emulate.c
index 38219af0cd0e..04e317c1bbee 100644
--- a/arch/powerpc/kvm/emulate.c
+++ b/arch/powerpc/kvm/emulate.c
@@ -143,6 +143,10 @@ int kvmppc_emulate_instruction(struct kvm_run *run, struct kvm_vcpu *vcpu)
pr_debug(KERN_INFO "Emulating opcode %d / %d\n", get_op(inst), get_xop(inst));
+ /* Try again next time */
+ if (inst == KVM_INST_FETCH_FAILED)
+ return EMULATE_DONE;
+
switch (get_op(inst)) {
case OP_TRAP:
#ifdef CONFIG_PPC64