Re: [PATCH 2/4] ppc/spapr: Add a nested state struct

[Harsh Prateek Bora <harshpb@linux.ibm.com>]

On 6/8/23 14:43, Nicholas Piggin wrote:
> Rather than use a copy of CPUPPCState to store the host state while
> the environment has been switched to the L2, use a new struct for
> this purpose.
> 
> Have helper functions to save and load this host state.
> 
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> ---
>   hw/ppc/spapr_hcall.c            | 150 ++++++++++++++++++++++++--------
>   include/hw/ppc/spapr_cpu_core.h |   5 +-
>   2 files changed, 115 insertions(+), 40 deletions(-)
> 
> diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
> index 0582b524d1..d5b8d54692 100644
> --- a/hw/ppc/spapr_hcall.c
> +++ b/hw/ppc/spapr_hcall.c
> @@ -1546,6 +1546,112 @@ static target_ulong h_copy_tofrom_guest(PowerPCCPU *cpu,
>       return H_FUNCTION;
>   }
>   
> +struct nested_ppc_state {
> +    uint64_t gpr[32];
> +    uint64_t lr;
> +    uint64_t ctr;
> +    uint64_t cfar;
> +    uint64_t msr;
> +    uint64_t nip;
> +    uint32_t cr;
> +
> +    uint64_t xer;
> +
> +    uint64_t lpcr;
> +    uint64_t lpidr;
> +    uint64_t pidr;
> +    uint64_t pcr;
> +    uint64_t dpdes;
> +    uint64_t hfscr;
> +    uint64_t srr0;
> +    uint64_t srr1;
> +    uint64_t sprg0;
> +    uint64_t sprg1;
> +    uint64_t sprg2;
> +    uint64_t sprg3;
> +    uint64_t ppr;
> +
> +    int64_t tb_offset;
> +};
> +

<snip>

> +static void nested_load_state(PowerPCCPU *cpu, struct nested_ppc_state *load)
> +{
> +    CPUState *cs = CPU(cpu);
> +    CPUPPCState *env = &cpu->env;
> +
> +    memcpy(env->gpr, load->gpr, sizeof(env->gpr));
> +
> +    env->lr = load->lr;
> +    env->ctr = load->ctr;
> +    env->cfar = load->cfar;
> +    env->msr = load->msr;
> +    env->nip = load->nip;
> +
> +    ppc_set_cr(env, load->cr);
> +    cpu_write_xer(env, load->xer);
> +
> +    env->spr[SPR_LPCR] = load->lpcr;
> +    env->spr[SPR_LPIDR] = load->lpidr;
> +    env->spr[SPR_PCR] = load->pcr;
> +    env->spr[SPR_DPDES] = load->dpdes;
> +    env->spr[SPR_HFSCR] = load->hfscr;
> +    env->spr[SPR_SRR0] = load->srr0;
> +    env->spr[SPR_SRR1] = load->srr1;
> +    env->spr[SPR_SPRG0] = load->sprg0;
> +    env->spr[SPR_SPRG1] = load->sprg1;
> +    env->spr[SPR_SPRG2] = load->sprg2;
> +    env->spr[SPR_SPRG3] = load->sprg3;
> +    env->spr[SPR_BOOKS_PID] = load->pidr;
> +    env->spr[SPR_PPR] = load->ppr;
> +
> +    env->tb_env->tb_offset = load->tb_offset;
> +
> +    /*
> +     * MSR updated, compute hflags and possible interrupts.
> +     */
> +    hreg_compute_hflags(env);
> +    ppc_maybe_interrupt(env);
> +
> +    /*
> +     * Nested HV does not tag TLB entries between L1 and L2, so must
> +     * flush on transition.
> +     */
> +    tlb_flush(cs);
> +    env->reserve_addr = -1; /* Reset the reservation */
> +}
> +

<snip>

> @@ -1766,34 +1872,8 @@ void spapr_exit_nested(PowerPCCPU *cpu, int excp)
>       address_space_unmap(CPU(cpu)->as, regs, len, len, true);
>   
>   out_restore_l1:
> -    memcpy(env->gpr, spapr_cpu->nested_host_state->gpr, sizeof(env->gpr));
> -    env->lr = spapr_cpu->nested_host_state->lr;
> -    env->ctr = spapr_cpu->nested_host_state->ctr;
> -    memcpy(env->crf, spapr_cpu->nested_host_state->crf, sizeof(env->crf));
> -    env->cfar = spapr_cpu->nested_host_state->cfar;
> -    env->xer = spapr_cpu->nested_host_state->xer;
> -    env->so = spapr_cpu->nested_host_state->so;
> -    env->ca = spapr_cpu->nested_host_state->ca;
> -    env->ov = spapr_cpu->nested_host_state->ov;
> -    env->ov32 = spapr_cpu->nested_host_state->ov32;
> -    env->ca32 = spapr_cpu->nested_host_state->ca32;

Above fields so, ca, ov, ov32, ca32 are not taken care in 
nested_load_state, ca being introduced in previous patch.

regards,
Harsh
> -    env->msr = spapr_cpu->nested_host_state->msr;
> -    env->nip = spapr_cpu->nested_host_state->nip;
> -
>       assert(env->spr[SPR_LPIDR] != 0);
> -    env->spr[SPR_LPCR] = spapr_cpu->nested_host_state->spr[SPR_LPCR];
> -    env->spr[SPR_LPIDR] = spapr_cpu->nested_host_state->spr[SPR_LPIDR];
> -    env->spr[SPR_PCR] = spapr_cpu->nested_host_state->spr[SPR_PCR];
> -    env->spr[SPR_DPDES] = 0;
> -    env->spr[SPR_HFSCR] = spapr_cpu->nested_host_state->spr[SPR_HFSCR];
> -    env->spr[SPR_SRR0] = spapr_cpu->nested_host_state->spr[SPR_SRR0];
> -    env->spr[SPR_SRR1] = spapr_cpu->nested_host_state->spr[SPR_SRR1];
> -    env->spr[SPR_SPRG0] = spapr_cpu->nested_host_state->spr[SPR_SPRG0];
> -    env->spr[SPR_SPRG1] = spapr_cpu->nested_host_state->spr[SPR_SPRG1];
> -    env->spr[SPR_SPRG2] = spapr_cpu->nested_host_state->spr[SPR_SPRG2];
> -    env->spr[SPR_SPRG3] = spapr_cpu->nested_host_state->spr[SPR_SPRG3];
> -    env->spr[SPR_BOOKS_PID] = spapr_cpu->nested_host_state->spr[SPR_BOOKS_PID];
> -    env->spr[SPR_PPR] = spapr_cpu->nested_host_state->spr[SPR_PPR];
> +    nested_load_state(cpu, spapr_cpu->nested_host_state);
>   
>       /*
>        * Return the interrupt vector address from H_ENTER_NESTED to the L1
> @@ -1801,14 +1881,8 @@ out_restore_l1:
>        */
>       env->gpr[3] = r3_return;
>   
> -    env->tb_env->tb_offset -= spapr_cpu->nested_tb_offset;
>       spapr_cpu->in_nested = false;
>   
> -    hreg_compute_hflags(env);
> -    ppc_maybe_interrupt(env);
> -    tlb_flush(cs);
> -    env->reserve_addr = -1; /* Reset the reservation */
> -
>       g_free(spapr_cpu->nested_host_state);
>       spapr_cpu->nested_host_state = NULL;
>   }
> diff --git a/include/hw/ppc/spapr_cpu_core.h b/include/hw/ppc/spapr_cpu_core.h
> index b560514560..69a52e39b8 100644
> --- a/include/hw/ppc/spapr_cpu_core.h
> +++ b/include/hw/ppc/spapr_cpu_core.h
> @@ -41,6 +41,8 @@ void spapr_cpu_set_entry_state(PowerPCCPU *cpu, target_ulong nip,
>                                  target_ulong r1, target_ulong r3,
>                                  target_ulong r4);
>   
> +struct nested_ppc_state;
> +
>   typedef struct SpaprCpuState {
>       uint64_t vpa_addr;
>       uint64_t slb_shadow_addr, slb_shadow_size;
> @@ -51,8 +53,7 @@ typedef struct SpaprCpuState {
>   
>       /* Fields for nested-HV support */
>       bool in_nested; /* true while the L2 is executing */
> -    CPUPPCState *nested_host_state; /* holds the L1 state while L2 executes */
> -    int64_t nested_tb_offset; /* L1->L2 TB offset */
> +    struct nested_ppc_state *nested_host_state; /* holds the L1 state while L2 executes */
>   } SpaprCpuState;
>   
>   static inline SpaprCpuState *spapr_cpu_state(PowerPCCPU *cpu)