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KVM: PPC: Allow kvmppc_get_last_inst() to fail

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On book3e, guest last instruction is read on the exit path using load
external pid (lwepx) dedicated instruction. This load operation may fail
due to TLB eviction and execute-but-not-read entries.

This patch lay down the path for an alternative solution to read the guest
last instruction, by allowing kvmppc_get_lat_inst() function to fail.
Architecture specific implmentations of kvmppc_load_last_inst() may read
last guest instruction and instruct the emulation layer to re-execute the
guest in case of failure.

Make kvmppc_get_last_inst() definition common between architectures.

Signed-off-by: Mihai Caraman <mihai.caraman@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
This commit is contained in:
Mihai Caraman
2014-07-23 19:06:21 +03:00
committed by Alexander Graf
parent 9a26af64d6
commit 51f047261e
11 changed files with 140 additions and 77 deletions
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18
arch/powerpc/kvm/emulate.c
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@@ -224,19 +224,25 @@ static int kvmppc_emulate_mfspr(struct kvm_vcpu *vcpu, int sprn, int rt)
* from opcode tables in the future. */
int kvmppc_emulate_instruction(struct kvm_run *run, struct kvm_vcpu *vcpu)
{
u32 inst = kvmppc_get_last_inst(vcpu);
int ra = get_ra(inst);
int rs = get_rs(inst);
int rt = get_rt(inst);
int sprn = get_sprn(inst);
enum emulation_result emulated = EMULATE_DONE;
u32 inst;
int ra, rs, rt, sprn;
enum emulation_result emulated;
int advance = 1;
/* this default type might be overwritten by subcategories */
kvmppc_set_exit_type(vcpu, EMULATED_INST_EXITS);
emulated = kvmppc_get_last_inst(vcpu, false, &inst);
if (emulated != EMULATE_DONE)
return emulated;
pr_debug("Emulating opcode %d / %d\n", get_op(inst), get_xop(inst));
ra = get_ra(inst);
rs = get_rs(inst);
rt = get_rt(inst);
sprn = get_sprn(inst);
switch (get_op(inst)) {
case OP_TRAP:
#ifdef CONFIG_PPC_BOOK3S