On 28.06.14 00:49, Mihai Caraman wrote:
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@xxxxxxxxxxxxx>
---
v4:
- these changes compile on book3s, please validate the functionality and
do the necessary adaptations!
- common declaration and enum for kvmppc_load_last_inst()
- remove kvmppc_read_inst() in a preceding patch
v3:
- rework patch description
- add common definition for kvmppc_get_last_inst()
- check return values in book3s code
v2:
- integrated kvmppc_get_last_inst() in book3s code and checked build
- addressed cosmetic feedback
arch/powerpc/include/asm/kvm_book3s.h | 26 ------------------
arch/powerpc/include/asm/kvm_booke.h | 5 ----
arch/powerpc/include/asm/kvm_ppc.h | 24 +++++++++++++++++
arch/powerpc/kvm/book3s.c | 11 ++++++++
arch/powerpc/kvm/book3s_64_mmu_hv.c | 17 ++++--------
arch/powerpc/kvm/book3s_paired_singles.c | 38 +++++++++++++++++----------
arch/powerpc/kvm/book3s_pr.c | 45 ++++++++++++++++++++++++--------
arch/powerpc/kvm/booke.c | 3 +++
arch/powerpc/kvm/e500_mmu_host.c | 6 +++++
arch/powerpc/kvm/emulate.c | 18 ++++++++-----
arch/powerpc/kvm/powerpc.c | 11 ++++++--
11 files changed, 128 insertions(+), 76 deletions(-)
diff --git a/arch/powerpc/include/asm/kvm_book3s.h b/arch/powerpc/include/asm/kvm_book3s.h
index ceb70aa..1300cd9 100644
--- a/arch/powerpc/include/asm/kvm_book3s.h
+++ b/arch/powerpc/include/asm/kvm_book3s.h
@@ -276,32 +276,6 @@ static inline bool kvmppc_need_byteswap(struct kvm_vcpu *vcpu)
return (kvmppc_get_msr(vcpu) & MSR_LE) != (MSR_KERNEL & MSR_LE);
}
-static inline u32 kvmppc_get_last_inst_internal(struct kvm_vcpu *vcpu, ulong pc)
-{
- /* Load the instruction manually if it failed to do so in the
- * exit path */
- if (vcpu->arch.last_inst == KVM_INST_FETCH_FAILED)
- kvmppc_ld(vcpu, &pc, sizeof(u32), &vcpu->arch.last_inst, false);
-
- return kvmppc_need_byteswap(vcpu) ? swab32(vcpu->arch.last_inst) :
- vcpu->arch.last_inst;
-}
-
-static inline u32 kvmppc_get_last_inst(struct kvm_vcpu *vcpu)
-{
- return kvmppc_get_last_inst_internal(vcpu, kvmppc_get_pc(vcpu));
-}
-
-/*
- * Like kvmppc_get_last_inst(), but for fetching a sc instruction.
- * Because the sc instruction sets SRR0 to point to the following
- * instruction, we have to fetch from pc - 4.
- */
-static inline u32 kvmppc_get_last_sc(struct kvm_vcpu *vcpu)
-{
- return kvmppc_get_last_inst_internal(vcpu, kvmppc_get_pc(vcpu) - 4);
-}
-
static inline ulong kvmppc_get_fault_dar(struct kvm_vcpu *vcpu)
{
return vcpu->arch.fault_dar;
diff --git a/arch/powerpc/include/asm/kvm_booke.h b/arch/powerpc/include/asm/kvm_booke.h
index c7aed61..cbb1990 100644
--- a/arch/powerpc/include/asm/kvm_booke.h
+++ b/arch/powerpc/include/asm/kvm_booke.h
@@ -69,11 +69,6 @@ static inline bool kvmppc_need_byteswap(struct kvm_vcpu *vcpu)
return false;
}
-static inline u32 kvmppc_get_last_inst(struct kvm_vcpu *vcpu)
-{
- return vcpu->arch.last_inst;
-}
-
static inline void kvmppc_set_ctr(struct kvm_vcpu *vcpu, ulong val)
{
vcpu->arch.ctr = val;
diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
index e2fd5a1..ec326c8 100644
--- a/arch/powerpc/include/asm/kvm_ppc.h
+++ b/arch/powerpc/include/asm/kvm_ppc.h
@@ -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 +242,22 @@ 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;
+
+ /* 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);
+
+ *inst = kvmppc_need_byteswap(vcpu) ? swab32(vcpu->arch.last_inst) :
+ vcpu->arch.last_inst;
We swap needlessly when the translation failed, but I don't think it
really hurts.
+
+ return ret;
So here we just return the return value of kvmppc_load_last_inst() ...
+}
+
static inline bool is_kvmppc_hv_enabled(struct kvm *kvm)
{
return kvm->arch.kvm_ops == kvmppc_hv_ops;
diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c
index bd75902..c17f101 100644
--- a/arch/powerpc/kvm/book3s.c
+++ b/arch/powerpc/kvm/book3s.c
@@ -467,6 +467,17 @@ mmio:
}
EXPORT_SYMBOL_GPL(kvmppc_ld);
+int kvmppc_load_last_inst(struct kvm_vcpu *vcpu, enum instruction_type type,
+ u32 *inst)
+{
+ ulong pc = kvmppc_get_pc(vcpu);
+
+ if (type == INST_SC)
+ pc -= 4;
+ return kvmppc_ld(vcpu, &pc, sizeof(u32), &vcpu->arch.last_inst, false);
... which simply returns the return value of kvmppc_ld(). However,
kvmppc_ld() returns -ENOENT when it doesn't find a translation. We need
to convert the return value space of kvmppc_ld() into an EMULATE_ name
space that makes sense for this function.
How about something like
r = kvmppc_ld();
if (r == EMULATE_DONE)
return r;
else
return EMULATE_AGAIN;
That way we make sure that we tell the caller only "yes, all is good" or
"please go back into the guest".
+}
+EXPORT_SYMBOL_GPL(kvmppc_load_last_inst);
+
int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
{
return 0;
diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c
index 8056107..2c2b7ad 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
@@ -530,21 +530,14 @@ static int instruction_is_store(unsigned int instr)
static int kvmppc_hv_emulate_mmio(struct kvm_run *run, struct kvm_vcpu *vcpu,
unsigned long gpa, gva_t ea, int is_store)
{
- int ret;
u32 last_inst;
- unsigned long srr0 = kvmppc_get_pc(vcpu);
- /* We try to load the last instruction. We don't let
- * emulate_instruction do it as it doesn't check what
- * kvmppc_ld returns.
+ /*
* If we fail, we just return to the guest and try executing it again.
*/
- if (vcpu->arch.last_inst == KVM_INST_FETCH_FAILED) {
- ret = kvmppc_ld(vcpu, &srr0, sizeof(u32), &last_inst, false);
- if (ret != EMULATE_DONE || last_inst == KVM_INST_FETCH_FAILED)
- return RESUME_GUEST;
- vcpu->arch.last_inst = last_inst;
- }
+ if (kvmppc_get_last_inst(vcpu, INST_GENERIC, &last_inst) !=
+ EMULATE_DONE)
+ return RESUME_GUEST;
This looks great.
/*
* WARNING: We do not know for sure whether the instruction we just
@@ -558,7 +551,7 @@ static int kvmppc_hv_emulate_mmio(struct kvm_run *run, struct kvm_vcpu *vcpu,
* we just return and retry the instruction.
*/
- if (instruction_is_store(kvmppc_get_last_inst(vcpu)) != !!is_store)
+ if (instruction_is_store(last_inst) != !!is_store)
return RESUME_GUEST;
/*
diff --git a/arch/powerpc/kvm/book3s_paired_singles.c b/arch/powerpc/kvm/book3s_paired_singles.c
index 6c8011f..bfb8035 100644
--- a/arch/powerpc/kvm/book3s_paired_singles.c
+++ b/arch/powerpc/kvm/book3s_paired_singles.c
@@ -639,26 +639,36 @@ static int kvmppc_ps_one_in(struct kvm_vcpu *vcpu, bool rc,
int kvmppc_emulate_paired_single(struct kvm_run *run, struct kvm_vcpu *vcpu)
{
- u32 inst = kvmppc_get_last_inst(vcpu);
+ u32 inst;
enum emulation_result emulated = EMULATE_DONE;
+ int ax_rd, ax_ra, ax_rb, ax_rc;
+ short full_d;
+ u64 *fpr_d, *fpr_a, *fpr_b, *fpr_c;
- int ax_rd = inst_get_field(inst, 6, 10);
- int ax_ra = inst_get_field(inst, 11, 15);
- int ax_rb = inst_get_field(inst, 16, 20);
- int ax_rc = inst_get_field(inst, 21, 25);
- short full_d = inst_get_field(inst, 16, 31);
-
- u64 *fpr_d = &VCPU_FPR(vcpu, ax_rd);
- u64 *fpr_a = &VCPU_FPR(vcpu, ax_ra);
- u64 *fpr_b = &VCPU_FPR(vcpu, ax_rb);
- u64 *fpr_c = &VCPU_FPR(vcpu, ax_rc);
-
- bool rcomp = (inst & 1) ? true : false;
- u32 cr = kvmppc_get_cr(vcpu);
+ bool rcomp;
+ u32 cr;
#ifdef DEBUG
int i;
#endif
+ emulated = kvmppc_get_last_inst(vcpu, INST_GENERIC, &inst);
+ if (emulated != EMULATE_DONE)
+ return emulated;
Here we're already leaking the "emulated" return value into the caller.
The caller in this chain should know what EMULATE_AGAIN means, so with
the change above we're safe.
+
+ ax_rd = inst_get_field(inst, 6, 10);
+ ax_ra = inst_get_field(inst, 11, 15);
+ ax_rb = inst_get_field(inst, 16, 20);
+ ax_rc = inst_get_field(inst, 21, 25);
+ full_d = inst_get_field(inst, 16, 31);
+
+ fpr_d = &VCPU_FPR(vcpu, ax_rd);
+ fpr_a = &VCPU_FPR(vcpu, ax_ra);
+ fpr_b = &VCPU_FPR(vcpu, ax_rb);
+ fpr_c = &VCPU_FPR(vcpu, ax_rc);
+
+ rcomp = (inst & 1) ? true : false;
+ cr = kvmppc_get_cr(vcpu);
+
if (!kvmppc_inst_is_paired_single(vcpu, inst))
return EMULATE_FAIL;
diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c
index d247d88..7bbaeec 100644
--- a/arch/powerpc/kvm/book3s_pr.c
+++ b/arch/powerpc/kvm/book3s_pr.c
@@ -970,15 +970,24 @@ int kvmppc_handle_exit_pr(struct kvm_run *run, struct kvm_vcpu *vcpu,
{
enum emulation_result er;
ulong flags;
+ u32 last_inst;
+ int emul;
program_interrupt:
flags = vcpu->arch.shadow_srr1 & 0x1f0000ull;
+ emul = kvmppc_get_last_inst(vcpu, INST_GENERIC, &last_inst);
+ if (emul != EMULATE_DONE) {
+ r = RESUME_GUEST;
Yes, this looks good.
+ break;
+ }
+
if (kvmppc_get_msr(vcpu) & MSR_PR) {
#ifdef EXIT_DEBUG
- printk(KERN_INFO "Userspace triggered 0x700 exception at 0x%lx (0x%x)\n", kvmppc_get_pc(vcpu), kvmppc_get_last_inst(vcpu));
+ pr_info("Userspace triggered 0x700 exception at\n 0x%lx (0x%x)\n",
+ kvmppc_get_pc(vcpu), last_inst);
#endif
- if ((kvmppc_get_last_inst(vcpu) & 0xff0007ff) !=
+ if ((last_inst & 0xff0007ff) !=
(INS_DCBZ & 0xfffffff7)) {
kvmppc_core_queue_program(vcpu, flags);
r = RESUME_GUEST;
@@ -997,7 +1006,7 @@ program_interrupt:
break;
case EMULATE_FAIL:
printk(KERN_CRIT "%s: emulation at %lx failed (%08x)\n",
- __func__, kvmppc_get_pc(vcpu), kvmppc_get_last_inst(vcpu));
+ __func__, kvmppc_get_pc(vcpu), last_inst);
kvmppc_core_queue_program(vcpu, flags);
r = RESUME_GUEST;
break;
@@ -1014,8 +1023,25 @@ program_interrupt:
break;
}
case BOOK3S_INTERRUPT_SYSCALL:
+ {
+ u32 last_sc;
+ int emul;
+
+ /* Get last sc for papr */
+ if (vcpu->arch.papr_enabled) {
+ /*
+ * The sc instuction sets SRR0 to point to the next inst
+ */
+ emul = kvmppc_get_last_inst(vcpu, INST_SC, &last_sc);
+ if (emul != EMULATE_DONE) {
+ kvmppc_set_pc(vcpu, kvmppc_get_pc(vcpu) - 4);
+ r = RESUME_GUEST;
This also looks good :).
+ break;
+ }
+ }
+
if (vcpu->arch.papr_enabled &&
- (kvmppc_get_last_sc(vcpu) == 0x44000022) &&
+ (last_sc == 0x44000022) &&
!(kvmppc_get_msr(vcpu) & MSR_PR)) {
/* SC 1 papr hypercalls */
ulong cmd = kvmppc_get_gpr(vcpu, 3);
@@ -1060,13 +1086,13 @@ program_interrupt:
r = RESUME_GUEST;
}
break;
+ }
case BOOK3S_INTERRUPT_FP_UNAVAIL:
case BOOK3S_INTERRUPT_ALTIVEC:
case BOOK3S_INTERRUPT_VSX:
{
int ext_msr = 0;
int emul;
- ulong pc;
u32 last_inst;
if (!(vcpu->arch.hflags & BOOK3S_HFLAG_PAIRED_SINGLE)) {
@@ -1090,9 +1116,7 @@ program_interrupt:
break;
}
- pc = kvmppc_get_pc(vcpu);
- last_inst = kvmppc_get_last_inst(vcpu);
- emul = kvmppc_ld(vcpu, &pc, sizeof(u32), &last_inst, false);
+ emul = kvmppc_get_last_inst(vcpu, INST_GENERIC, &last_inst);
if (emul == EMULATE_DONE) {
/* we need to emulate this instruction */
goto program_interrupt;
@@ -1105,9 +1129,8 @@ program_interrupt:
}
case BOOK3S_INTERRUPT_ALIGNMENT:
{
- ulong pc = kvmppc_get_pc(vcpu);
- u32 last_inst = kvmppc_get_last_inst(vcpu);
- int emul = kvmppc_ld(vcpu, &pc, sizeof(u32), &last_inst, false);
+ u32 last_inst;
+ int emul = kvmppc_get_last_inst(vcpu, INST_GENERIC, &last_inst);
if (emul == EMULATE_DONE) {
u32 dsisr;
diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index ab62109..34a42b9 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -752,6 +752,9 @@ static int emulation_exit(struct kvm_run *run, struct kvm_vcpu *vcpu)
* they were actually modified by emulation. */
return RESUME_GUEST_NV;
+ case EMULATE_AGAIN:
+ return RESUME_GUEST;
Yup :).
+
case EMULATE_DO_DCR:
run->exit_reason = KVM_EXIT_DCR;
return RESUME_HOST;
diff --git a/arch/powerpc/kvm/e500_mmu_host.c b/arch/powerpc/kvm/e500_mmu_host.c
index dd2cc03..4b4e8d6 100644
--- a/arch/powerpc/kvm/e500_mmu_host.c
+++ b/arch/powerpc/kvm/e500_mmu_host.c
@@ -606,6 +606,12 @@ void kvmppc_mmu_map(struct kvm_vcpu *vcpu, u64 eaddr, gpa_t gpaddr,
}
}
+int kvmppc_load_last_inst(struct kvm_vcpu *vcpu, enum instruction_type type,
+ u32 *instr)
+{
+ return EMULATE_FAIL;
This should be EMULATE_AGAIN, no?
+}
+
/************* MMU Notifiers *************/
int kvm_unmap_hva(struct kvm *kvm, unsigned long hva)
diff --git a/arch/powerpc/kvm/emulate.c b/arch/powerpc/kvm/emulate.c
index da86d9b..c5c64b6 100644
--- a/arch/powerpc/kvm/emulate.c
+++ b/arch/powerpc/kvm/emulate.c
@@ -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;
and here we're leaking again ;). It's perfectly fine to do so, but let's
make sure we don't leak -ENOENT :). So here too the fix above should
make things work.
Alex
+
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
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 7efc2b7..da54e4b 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -261,6 +261,9 @@ int kvmppc_emulate_mmio(struct kvm_run *run, struct kvm_vcpu *vcpu)
* actually modified. */
r = RESUME_GUEST_NV;
break;
+ case EMULATE_AGAIN:
+ r = RESUME_GUEST;
+ break;
case EMULATE_DO_MMIO:
run->exit_reason = KVM_EXIT_MMIO;
/* We must reload nonvolatiles because "update" load/store
@@ -270,11 +273,15 @@ int kvmppc_emulate_mmio(struct kvm_run *run, struct kvm_vcpu *vcpu)
r = RESUME_HOST_NV;
break;
case EMULATE_FAIL:
+ {
+ u32 last_inst;
+
+ kvmppc_get_last_inst(vcpu, false, &last_inst);
/* XXX Deliver Program interrupt to guest. */
- printk(KERN_EMERG "%s: emulation failed (%08x)\n", __func__,
- kvmppc_get_last_inst(vcpu));
+ pr_emerg("%s: emulation failed (%08x)\n", __func__, last_inst);
r = RESUME_HOST;
break;
+ }
default:
WARN_ON(1);
r = RESUME_GUEST;
--
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