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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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31
arch/powerpc/include/asm/kvm_ppc.h
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@@ -47,6 +47,11 @@ enum emulation_result {
EMULATE_EXIT_USER, /* emulation requires exit to user-space */
};
enum instruction_type {
INST_GENERIC,
INST_SC, /* system call */
};
extern int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu);
extern int __kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu);
extern void kvmppc_handler_highmem(void);
@@ -62,6 +67,9 @@ extern int kvmppc_handle_store(struct kvm_run *run, struct kvm_vcpu *vcpu,
u64 val, unsigned int bytes,
int is_default_endian);
extern int kvmppc_load_last_inst(struct kvm_vcpu *vcpu,
enum instruction_type type, u32 *inst);
extern int kvmppc_emulate_instruction(struct kvm_run *run,
struct kvm_vcpu *vcpu);
extern int kvmppc_emulate_mmio(struct kvm_run *run, struct kvm_vcpu *vcpu);
@@ -234,6 +242,29 @@ struct kvmppc_ops {
extern struct kvmppc_ops *kvmppc_hv_ops;
extern struct kvmppc_ops *kvmppc_pr_ops;
static inline int kvmppc_get_last_inst(struct kvm_vcpu *vcpu,
enum instruction_type type, u32 *inst)
{
int ret = EMULATE_DONE;
u32 fetched_inst;
/* Load the instruction manually if it failed to do so in the
* exit path */
if (vcpu->arch.last_inst == KVM_INST_FETCH_FAILED)
ret = kvmppc_load_last_inst(vcpu, type, &vcpu->arch.last_inst);
/* Write fetch_failed unswapped if the fetch failed */
if (ret == EMULATE_DONE)
fetched_inst = kvmppc_need_byteswap(vcpu) ?
swab32(vcpu->arch.last_inst) :
vcpu->arch.last_inst;
else
fetched_inst = vcpu->arch.last_inst;
*inst = fetched_inst;
return ret;
}
static inline bool is_kvmppc_hv_enabled(struct kvm *kvm)
{
return kvm->arch.kvm_ops == kvmppc_hv_ops;