[RFC PATCH 3/4] spapr: load and store l2 state with helper functions

[Nicholas Piggin <npiggin@gmail.com>]

Arguably this is just shuffling around register accesses, but one nice
thing it does is allow the exit to save away the L2 state then switch
the environment to the L1 before copying L2 data back to the L1, which
logically flows more naturally and simplifies the error paths.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 hw/ppc/spapr_hcall.c | 178 +++++++++++++++++++++----------------------
 1 file changed, 85 insertions(+), 93 deletions(-)

diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
index 6679150ac7..783a06ba98 100644
--- a/hw/ppc/spapr_hcall.c
+++ b/hw/ppc/spapr_hcall.c
@@ -1675,9 +1675,9 @@ static target_ulong h_enter_nested(PowerPCCPU *cpu,
                                    target_ulong *args)
 {
     PowerPCCPUClass *pcc = POWERPC_CPU_GET_CLASS(cpu);
-    CPUState *cs = CPU(cpu);
     CPUPPCState *env = &cpu->env;
     SpaprCpuState *spapr_cpu = spapr_cpu_state(cpu);
+    struct nested_ppc_state l2_state;
     target_ulong hv_ptr = args[0];
     target_ulong regs_ptr = args[1];
     target_ulong hdec, now = cpu_ppc_load_tbl(env);
@@ -1686,8 +1686,6 @@ static target_ulong h_enter_nested(PowerPCCPU *cpu,
     struct kvmppc_hv_guest_state hv_state;
     struct kvmppc_pt_regs *regs;
     hwaddr len;
-    uint64_t cr;
-    int i;
 
     if (spapr->nested_ptcr == 0) {
         return H_NOT_AVAILABLE;
@@ -1713,6 +1711,10 @@ static target_ulong h_enter_nested(PowerPCCPU *cpu,
         return H_PARAMETER;
     }
 
+    if (hv_state.lpid == 0) {
+        return H_PARAMETER;
+    }
+
     spapr_cpu->nested_host_state = g_try_new(struct nested_ppc_state, 1);
     if (!spapr_cpu->nested_host_state) {
         return H_NO_MEM;
@@ -1731,51 +1733,49 @@ static target_ulong h_enter_nested(PowerPCCPU *cpu,
         return H_P2;
     }
 
-    len = sizeof(env->gpr);
+    len = sizeof(l2_state.gpr);
     assert(len == sizeof(regs->gpr));
-    memcpy(env->gpr, regs->gpr, len);
+    memcpy(l2_state.gpr, regs->gpr, len);
 
-    env->lr = regs->link;
-    env->ctr = regs->ctr;
-    cpu_write_xer(env, regs->xer);
-
-    cr = regs->ccr;
-    for (i = 7; i >= 0; i--) {
-        env->crf[i] = cr & 15;
-        cr >>= 4;
-    }
-
-    env->msr = regs->msr;
-    env->nip = regs->nip;
+    l2_state.lr = regs->link;
+    l2_state.ctr = regs->ctr;
+    l2_state.xer = regs->xer;
+    l2_state.cr = regs->ccr;
+    l2_state.msr = regs->msr;
+    l2_state.nip = regs->nip;
 
     address_space_unmap(CPU(cpu)->as, regs, len, len, false);
 
-    env->cfar = hv_state.cfar;
-
-    assert(env->spr[SPR_LPIDR] == 0);
-    env->spr[SPR_LPIDR] = hv_state.lpid;
+    l2_state.cfar = hv_state.cfar;
+    l2_state.lpidr = hv_state.lpid;
 
     lpcr_mask = LPCR_DPFD | LPCR_ILE | LPCR_AIL | LPCR_LD | LPCR_MER;
     lpcr = (env->spr[SPR_LPCR] & ~lpcr_mask) | (hv_state.lpcr & lpcr_mask);
     lpcr |= LPCR_HR | LPCR_UPRT | LPCR_GTSE | LPCR_HVICE | LPCR_HDICE;
     lpcr &= ~LPCR_LPES0;
-    env->spr[SPR_LPCR] = lpcr & pcc->lpcr_mask;
+    l2_state.lpcr = lpcr & pcc->lpcr_mask;
 
-    env->spr[SPR_PCR] = hv_state.pcr;
+    l2_state.pcr = hv_state.pcr;
     /* hv_state.amor is not used */
-    env->spr[SPR_DPDES] = hv_state.dpdes;
-    env->spr[SPR_HFSCR] = hv_state.hfscr;
-    hdec = hv_state.hdec_expiry - now;
+    l2_state.dpdes = hv_state.dpdes;
+    l2_state.hfscr = hv_state.hfscr;
     /* TCG does not implement DAWR*, CIABR, PURR, SPURR, IC, VTB, HEIR SPRs*/
-    env->spr[SPR_SRR0] = hv_state.srr0;
-    env->spr[SPR_SRR1] = hv_state.srr1;
-    env->spr[SPR_SPRG0] = hv_state.sprg[0];
-    env->spr[SPR_SPRG1] = hv_state.sprg[1];
-    env->spr[SPR_SPRG2] = hv_state.sprg[2];
-    env->spr[SPR_SPRG3] = hv_state.sprg[3];
-    env->spr[SPR_BOOKS_PID] = hv_state.pidr;
-    env->spr[SPR_PPR] = hv_state.ppr;
+    l2_state.srr0 = hv_state.srr0;
+    l2_state.srr1 = hv_state.srr1;
+    l2_state.sprg0 = hv_state.sprg[0];
+    l2_state.sprg1 = hv_state.sprg[1];
+    l2_state.sprg2 = hv_state.sprg[2];
+    l2_state.sprg3 = hv_state.sprg[3];
+    l2_state.pidr = hv_state.pidr;
+    l2_state.ppr = hv_state.ppr;
+    l2_state.tb_offset = env->tb_env->tb_offset + hv_state.tb_offset;
 
+    /*
+     * Switch to the nested guest environment and start the "hdec" timer.
+     */
+    nested_load_state(cpu, &l2_state);
+
+    hdec = hv_state.hdec_expiry - now;
     cpu_ppc_hdecr_init(env);
     cpu_ppc_store_hdecr(env, hdec);
 
@@ -1791,14 +1791,8 @@ static target_ulong h_enter_nested(PowerPCCPU *cpu,
      * and it's not obviously worth a new data structure to do it.
      */
 
-    env->tb_env->tb_offset += hv_state.tb_offset;
     spapr_cpu->in_nested = true;
 
-    hreg_compute_hflags(env);
-    ppc_maybe_interrupt(env);
-    tlb_flush(cs);
-    env->reserve_addr = -1; /* Reset the reservation */
-
     /*
      * The spapr hcall helper sets env->gpr[3] to the return value, but at
      * this point the L1 is not returning from the hcall but rather we
@@ -1812,51 +1806,69 @@ void spapr_exit_nested(PowerPCCPU *cpu, int excp)
 {
     CPUPPCState *env = &cpu->env;
     SpaprCpuState *spapr_cpu = spapr_cpu_state(cpu);
-    target_ulong r3_return = env->excp_vectors[excp]; /* hcall return value */
+    struct nested_ppc_state l2_state;
     target_ulong hv_ptr = spapr_cpu->nested_host_state->gpr[4];
     target_ulong regs_ptr = spapr_cpu->nested_host_state->gpr[5];
+    target_ulong hsrr0, hsrr1, hdar, asdr, hdsisr;
     struct kvmppc_hv_guest_state *hvstate;
     struct kvmppc_pt_regs *regs;
     hwaddr len;
-    uint64_t cr;
-    int i;
 
     assert(spapr_cpu->in_nested);
 
+    nested_save_state(&l2_state, cpu);
+    hsrr0 = env->spr[SPR_HSRR0];
+    hsrr1 = env->spr[SPR_HSRR1];
+    hdar = env->spr[SPR_HDAR];
+    hdsisr = env->spr[SPR_HDSISR];
+    asdr = env->spr[SPR_ASDR];
+
+    /*
+     * Switch back to the host environment (including for any error).
+     */
+    assert(env->spr[SPR_LPIDR] != 0);
+    nested_load_state(cpu, spapr_cpu->nested_host_state);
+    env->gpr[3] = env->excp_vectors[excp]; /* hcall return value */
+
     cpu_ppc_hdecr_exit(env);
 
+    spapr_cpu->in_nested = false;
+
+    g_free(spapr_cpu->nested_host_state);
+    spapr_cpu->nested_host_state = NULL;
+
     len = sizeof(*hvstate);
     hvstate = address_space_map(CPU(cpu)->as, hv_ptr, &len, true,
                                 MEMTXATTRS_UNSPECIFIED);
     if (len != sizeof(*hvstate)) {
         address_space_unmap(CPU(cpu)->as, hvstate, len, 0, true);
-        r3_return = H_PARAMETER;
-        goto out_restore_l1;
+        env->gpr[3] = H_PARAMETER;
+	return;
     }
 
-    hvstate->cfar = env->cfar;
-    hvstate->lpcr = env->spr[SPR_LPCR];
-    hvstate->pcr = env->spr[SPR_PCR];
-    hvstate->dpdes = env->spr[SPR_DPDES];
-    hvstate->hfscr = env->spr[SPR_HFSCR];
+    hvstate->cfar = l2_state.cfar;
+    hvstate->lpcr = l2_state.lpcr;
+    hvstate->pcr = l2_state.pcr;
+    hvstate->dpdes = l2_state.dpdes;
+    hvstate->hfscr = l2_state.hfscr;
 
     if (excp == POWERPC_EXCP_HDSI) {
-        hvstate->hdar = env->spr[SPR_HDAR];
-        hvstate->hdsisr = env->spr[SPR_HDSISR];
-        hvstate->asdr = env->spr[SPR_ASDR];
+        hvstate->hdar = hdar;
+        hvstate->hdsisr = hdsisr;
+        hvstate->asdr = asdr;
     } else if (excp == POWERPC_EXCP_HISI) {
-        hvstate->asdr = env->spr[SPR_ASDR];
+        hvstate->asdr = asdr;
     }
 
     /* HEIR should be implemented for HV mode and saved here. */
-    hvstate->srr0 = env->spr[SPR_SRR0];
-    hvstate->srr1 = env->spr[SPR_SRR1];
-    hvstate->sprg[0] = env->spr[SPR_SPRG0];
-    hvstate->sprg[1] = env->spr[SPR_SPRG1];
-    hvstate->sprg[2] = env->spr[SPR_SPRG2];
-    hvstate->sprg[3] = env->spr[SPR_SPRG3];
-    hvstate->pidr = env->spr[SPR_BOOKS_PID];
-    hvstate->ppr = env->spr[SPR_PPR];
+    hvstate->srr0 = l2_state.srr0;
+    hvstate->srr1 = l2_state.srr1;
+    hvstate->sprg[0] = l2_state.sprg0;
+    hvstate->sprg[1] = l2_state.sprg1;
+    hvstate->sprg[2] = l2_state.sprg2;
+    hvstate->sprg[3] = l2_state.sprg3;
+    hvstate->pidr = l2_state.pidr;
+    hvstate->ppr = l2_state.ppr;
 
     /* Is it okay to specify write length larger than actual data written? */
     address_space_unmap(CPU(cpu)->as, hvstate, len, len, true);
@@ -1866,51 +1878,31 @@ void spapr_exit_nested(PowerPCCPU *cpu, int excp)
                                 MEMTXATTRS_UNSPECIFIED);
     if (!regs || len != sizeof(*regs)) {
         address_space_unmap(CPU(cpu)->as, regs, len, 0, true);
-        r3_return = H_P2;
-        goto out_restore_l1;
+        env->gpr[3] = H_P2;
+	return;
     }
 
     len = sizeof(env->gpr);
     assert(len == sizeof(regs->gpr));
-    memcpy(regs->gpr, env->gpr, len);
+    memcpy(regs->gpr, l2_state.gpr, len);
 
-    regs->link = env->lr;
-    regs->ctr = env->ctr;
-    regs->xer = cpu_read_xer(env);
-
-    cr = 0;
-    for (i = 0; i < 8; i++) {
-        cr |= (env->crf[i] & 15) << (4 * (7 - i));
-    }
-    regs->ccr = cr;
+    regs->link = l2_state.lr;
+    regs->ctr = l2_state.ctr;
+    regs->xer = l2_state.xer;
+    regs->ccr = l2_state.cr;
 
     if (excp == POWERPC_EXCP_MCHECK ||
         excp == POWERPC_EXCP_RESET ||
         excp == POWERPC_EXCP_SYSCALL) {
-        regs->nip = env->spr[SPR_SRR0];
-        regs->msr = env->spr[SPR_SRR1] & env->msr_mask;
+        regs->nip = l2_state.srr0;
+        regs->msr = l2_state.srr1 & env->msr_mask;
     } else {
-        regs->nip = env->spr[SPR_HSRR0];
-        regs->msr = env->spr[SPR_HSRR1] & env->msr_mask;
+        regs->nip = hsrr0;
+        regs->msr = hsrr1 & env->msr_mask;
     }
 
     /* Is it okay to specify write length larger than actual data written? */
     address_space_unmap(CPU(cpu)->as, regs, len, len, true);
-
-out_restore_l1:
-    assert(env->spr[SPR_LPIDR] != 0);
-    nested_load_state(cpu, spapr_cpu->nested_host_state);
-
-    /*
-     * Return the interrupt vector address from H_ENTER_NESTED to the L1
-     * (or error code).
-     */
-    env->gpr[3] = r3_return;
-
-    spapr_cpu->in_nested = false;
-
-    g_free(spapr_cpu->nested_host_state);
-    spapr_cpu->nested_host_state = NULL;
 }
 
 static void hypercall_register_nested(void)
-- 
2.40.1