KVM: PPC: Allow kvmppc_get_last_inst() to fail

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>

diff --git a/arch/powerpc/include/asm/kvm_book3s.h b/arch/powerpc/include/asm/kvm_book3s.h
index 20fb6f2..a86ca65 100644 (file)
--- 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 (file)
--- 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 246fb9a..e381363 100644 (file)
--- 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 +242,29 @@ 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;

diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c
index 31facfc..37ca8a0 100644 (file)
--- a/arch/powerpc/kvm/book3s.c
+++ b/arch/powerpc/kvm/book3s.c
@@ -488,6 +488,23 @@ 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);
+       int r;
+
+       if (type == INST_SC)
+               pc -= 4;
+
+       r = kvmppc_ld(vcpu, &pc, sizeof(u32), inst, false);
+       if (r == EMULATE_DONE)
+               return r;
+       else
+               return EMULATE_AGAIN;
+}
+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 2d154d9..fa944a3 100644 (file)
--- 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;
 
        /*
         * 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 (file)
--- 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;
+
+       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 e76aec3..b18f2d4 100644 (file)
--- a/arch/powerpc/kvm/book3s_pr.c
+++ b/arch/powerpc/kvm/book3s_pr.c
@@ -1018,15 +1018,24 @@ 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;
+                       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;
@@ -1045,7 +1054,7 @@ 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;
@@ -1062,8 +1071,23 @@ 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 points SRR0 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;
+                               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);
@@ -1108,21 +1132,19 @@ 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) {
                        /* Do paired single instruction emulation */
-                       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)
                                goto program_interrupt;
                        else
@@ -1151,9 +1173,8 @@ 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 a06ef6b..50df5e3 100644 (file)
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -702,6 +702,9 @@ 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;
+
        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 79677d7..4385c14 100644 (file)
--- a/arch/powerpc/kvm/e500_mmu_host.c
+++ b/arch/powerpc/kvm/e500_mmu_host.c
@@ -610,6 +610,12 @@ 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_AGAIN;
+}
+
 /************* 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 (file)
--- 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;
+
        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 fe0257a..cfa6cfa 100644 (file)
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -280,6 +280,9 @@ 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
@@ -289,11 +292,15 @@ 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;